Reference and Consciousness

OXFORD C O G N I T I V E S C I E N C E S E R I E S REFERENCE AND CONSCIOUSNESS

OXFORD C O G N I T I V E SCIENCE SERIES General Editors MARTIN DAVIES, JAMES HIGGINBOTHAM, PHILIP JOHNSON-LAIRD, CHRISTOPHER PEACOCKE, KIM PLUNKETT

Published in the series Concepts: Where Cognitive Science Went Wrong Jerry A. Fodor Context and Content Robert C. Stalnaker Mindreading Stephen Stich and Shaun Nichols Face and Mind: The Science of Face Perception Andy Young

REFERENCE AND CONSCIOUSNESS JOHN CAMPBELL

CLARENDON PRESS • OXFORD

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OXFORD UNIVERSITY PRESS Great Clarendon Street, Oxford 0X2 6DP Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Bangkok Buenos Aires Cape Town Chennai Dar es Salaam Delhi Hong Kong Istanbul Karachi Kolkata Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi Sao Paulo Shanghai Taipei Tokyo Toronto Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States ©John Campbell 2002 The moral rights of the author have been asserted Database right Oxford University Press (maker) Reprinted 2003 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer ISBN 0-19-924380-8

PREFACE

In May 1995, Naomi Eilan and Michael Martin organized a one-day meeting in London on 'Attention and Consciousness' in which I was to be cosymposiast with Jon Driver. Driver's talk, presenting results about the connections between acts of perceptual attention in different sensory modalities, seemed to me fascinating but difficult to interpret in terms of its implications for the character of experience. I found, however, an immediate and intuitive connection between Driver's findings and a problem that had long interested me, namely the connections between references to objects made on the basis of perceptions of them in different sensory modalities, such as sight or touch or hearing. To refer to an object on the basis of seeing it seems to require attention to that object; to refer to an object on the basis of hearing it or touching it seems to require attention to that object. So in principle, I thought, it ought to be possible to use results on relations between acts of attention in different sensory modalities to illuminate the relations between, for example, demonstratives referring to seen objects and demonstratives referring to touched or heard objects. In pursuing this line of thought after the conference, though, it quickly became apparent to me that the fundamental problem is to articulate the relation between attention to an object and knowledge of the reference of a demonstrative referring to it. The issue of the relations among the sensory modalities is touched on only glancingly in this book, though I think there are ready extensions of the present approach to that topic. Rather, I have gone back to the original topic of the London conference, to find the relations now between three phenomena: attention, knowledge of reference, and our experience of the world. In finding my way around the basic conceptual links between these three notions—attention, knowledge of reference, and experience—I have been greatly helped by a long series of sceptical challenges from Philippa Foot. Christopher Peacocke provided a detailed set of comments on four chapters from an early draft. Quassim Cassam and Timothy Williamson helped me see the exact shape of many particular arguments in an area whose scope, though narrowly defined, is quite far-reaching. And most of all, I have tried in one way or another to address Michael Dummett's deeply thought-through set of challenges for any account of knowledge of reference.

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On vision science, I learned a lot from discussions with Charles Spence, Vincent Walsh, Kia Nobre, Peter McLeod, Alan Allport, Andrew Parker, and Stephen Palmer. In this book 1 appeal only to some simple, robust points about visual attention. But these people helped me find my way to them, and to see why even those findings might be problematic. In connecting the empirical with the philosophical I was also much assisted by a centre for such work in the U.K., the Consciousness and SelfConsciousness group based at Warwick University, in particular to Naomi Eilan, Christoph Hoerl, Teresa McCormack, and Johannes Roessler. At various points I have had sustained and helpful discussion of the approach with Paul Boghossian, Bill Brewer, David Charles, Tamar Gendler, Alison Gopnik, John O'Leary Hawthorne, Sydney Shoemaker, Charles Travis, and David Wiggins. Jeremy Butterfield forced a number of changes to my discussion of causation in Chapter 12; Michael Bacharach provided a generous stimulus to the remarks on common knowledge in Chapter 8. The basic forum in which I have discussed these ideas has been a set of graduate classes given in Oxford in most terms since 1995. I have had countless illuminating and searching comments from many participants; in particular, I would like to thank Stephen Butterfill, Imogen Dickie, Kostja New, Hanna Pickard, and Oliver Pooley. I have given talks from this material at a number of universities, and always learned from the discussions: my immediate memories of illumination include moments at Barcelona, Berkeley, Cornell, CREA (Paris), Edinburgh, Glasgow, Lisbon, London, NYU, Oxford, Palermo, Riverside, Salzburg, St Andrews, Stirling, UCLA, Vassar, and Warwick. Portions of this material have had formal commentaries from Julien Deonna, Jerome Dokic, Rae Langton, Brian Loar, Kirk Ludwig, and Michael Martin. Various early versions or alternative versions of this material have been published as: 'Molyneux's Question', in Enrique Villanueva (ed.), Perception: Philosophical Issues, 7 (Ridgeview: Atascadero, Calif., 1996), 301-18, with replies by Brian Loar and Kirk Ludwig. 'Sense, Reference and Selective Attention', Proceedings of the Aristotelian Society, Supplementary Volume, 71 (1997), 55-74, with a reply by Michael Martin. Attention and Frames of Reference in Spatial Reasoning', Mind and Language, 12 (1997), 265-77. 'Joint Attention and the First Person', in Anthony O'Hear (ed.), Current Issues in Philosophy of Mind: Royal Institute of Philosophy

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Annual Supplement, 43 (Cambridge: Cambridge University Press, 1998), 123-136. 'Sense and Consciousness', in Peter Sullivan and Johannes Brandl (eds.), New Essays on the Philosophy of Michael Dummett: Grazer Philosophische Studien, 55 (1998), 195-211. 'Immunity to Error through Misidentification and the Meaning of a Referring Term', Philosophical Topics, 26 (1999), 89-104. 'Memory Demonstratives', in Christoph Hoerl and Teresa McCormack (eds.), Time and Memory (Oxford: Oxford University Press, 2001), 169-86. 'Berkeley's Puzzle', in Tamar Szabo Gendler and John O'Leary Hawthorne (eds.), Imagination, Conceivability and Possibility (Oxford: Oxford University Press, 2002). I could not have begun on this work in earnest without the benefit of a British Academy Research Readership, which I held during 1995-7, which gave me the time to learn something about these matters. In the course of writing this book, I was given a renewed sense of purpose, on many occasions, by Allison Harvey; so my final thanks go to Michel Treisman, who introduced us.

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CONTENTS

Introduction 1. Experiential Highlighting

1 7

2. What is Knowledge of Reference?

22

3. Space and Action

46

4. Sortals

61

5. Sense

84

6. The Relational View of Experience

114

7. The Explanatory Role of Consciousness

132

8. Joint Attention

157

9. Memory Demonstratives

177

10. The Anti-Realist Alternative

194

11. Indeterminacy and Inscrutability

216

12. Dispositional vs. Categorical

235

Bibliography

255

Index

265

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Introduction It is experience of the world that puts us in a position to think about it. Without experience, we would not know what the world is like. Those who have experiences of which we know nothing may be able to think in ways of which we know nothing. Those who do not have our experience of the world will not be able to think of it as we do. These points show up even at the simplest levels. Someone who has never had experience of the colours will not be able to understand the concepts of the different colours. As Locke said, a scholarly and indeed brilliant individual born blind, on pursuing an investigation into the nature of the various colours, may eventually say of scarlet, "Tis like the sound of a trumpet!', but this will not reflect any knowledge of what scarlet is. Or again, if I have picked something up and I conceal it from you, I may make a series of remarks to you about 'this extraordinary object', but the most direct way for you to interpret my remarks is by experiencing the object itself; seeing the object would mean that you knew what I was referring to. This connection between reference and consciousness is one that has been lost sight of. The complexity of the issues surrounding the two topics individually has led to a fragmentation of effort in theorizing about them. Reference is one problem, consciousness is another. This means that it is easy to lose sight of ways in which the two problems illuminate each other. We understand reference better when we keep in view that it is at bottom a phenomenon of consciousness. We know better how to think about consciousness when we know that, whatever else is true of it, consciousness of objects is what provides knowledge of reference. This gives some discipline to theorizing about consciousness: of what we say about consciousness, we can ask whether it contributes to explaining how consciousness can be what provides knowledge of reference. There is a way of focusing discussion of this connection which appeals to the notion of attention. Reference and attention are generally taken to be different topics. Reference is one of the fundamental problems in philosophy, though the nature of reference is not often directly discussed by scientists: the general problem is how our thoughts and words connect to the things about which we think and talk. Attention, in contrast, is little

2

introduction

discusse d by philosophers, but one of the most intensively studied phenomena in cognitive science. To see why attention seems important in cognitive science, suppose for a moment that you think about a human being as an engineer might view the thing. There is a lot of machinery here, in the human being, which can be deployed now on this task, now on that. What makes the difference between the machinery being deployed on this object as opposed to that object, is a difference in what you are attending to. Attention is an element in the control of the whole system. So reference and attention seem individually to be important topics, in philosophy and psychology respectively, yet to have little to do with one another. Suppose, though, that you and I are sitting side by side looking at a cityscape, a panorama of buildings. If I am to think about any one of those buildings, if I am to formulate conjectures or questions about any of those buildings, if I am to be able to refer to any one of those buildings in my own thoughts, it is not enough that the building should simply be there, somewhere or other in my field of view. If it is simply there in my field of view, though unnoticed by me, I am not yet in a position to refer to it; I cannot yet think about it. If I am to think about it, 1 have to single out the building visually: I have to attend to it. And if I want to refer to that building, to make a remark about that building for your benefit, I have to draw your attention to it. That is what pointing is. Pointing is at once the most basic kind of reference to objects, and the single most useful way of drawing someone else's attention to an object. So reference and attention are not just different topics. When we think about demonstrative reference in particular—that is, reference made to a currently perceived object on the basis of current perception of it—it seems that reference to the object depends on attention to the object. So we should expect that philosophical problems about reference and psychological theorizing about attention should be capable of illuminating one another. It is attention as a phenomenon of consciousness that matters for knowledge of reference. If I am to understand a demonstrative referring to an object, it is not enough merely that the object be there somewhere in my visual field; I have to attend to it. But the attention that is needed here is, as it were, a matter of experiential highlighting of the object; it is not enough merely that there be some shifts in the architecture of my information-processing machinery, remote from consciousness. To understand how knowledge of reference depends on attention we will have to understand the relation between the experiential highlighting of an object and underlying shifts in the configuration of information-processing machinery. We can make a rough division between a description of what knowledge of reference is, and a description of what knowledge of reference does. When I say that knowledge of reference is provided by conscious attention

Introduction

3

to the object, this is a description of what knowledge of reference is, and I will amplify it by looking in detail at what conception of consciousness, and what conception of conscious attention in particular, we need to be appealing to here. But we also have to look at what knowledge of reference does—what the significance is of knowledge of reference. I think that, given a preliminary characterization of knowledge of reference as provided by conscious attention to the object, we can get at this by looking at the functional role of conscious attention, and, in particular, by articulating the relation between attention as a phenomenon of consciousness and attention as an information-processing phenomenon. The general line of my argument is this. There are many information-processing systems that run automatically, in parallel, and they are not, usually, directly affected by attentional shifts. For example, low-level vision or reflex movement may be of this type. But sometimes information-processing is carried out under more central control. For example, the motor processing involved in executing a voluntary action is not run automatically: it is responsive to the conscious intentions of the subject. Similarly, if you are, as it were, visually interrogating a scene, for example if you are a policeman looking for signs of trouble, the visual information-processing you are performing is in the service of your conscious objectives; once you believe you are off-duty your vigilance may relax and the information-processing is simply no longer performed. This implies that conscious attention to an object—the experiential highlighting of that aspect of your perception—means that this aspect of your experience has a different functional role to the functional role it had when it was not so highlighted. That aspect of your conscious experience is now connected to certain information-processing machinery in a way in which it was not previously so connected. It is one of the factors which cause that information-processing machinery to swing into play, and it also defines the objective of the information-processing machinery. So we can ask the question just how conscious experience of the object manages to identify the target of the information-processing machinery. Rather than seeing consciousness and information-processing as systems causally insulated from one another, we have to see them as causally explaining each other's movements, and we have to find the commensurability between the way in which conscious experience identifies the objects we think about, and the way in which the targets of informationprocessing are identified. Let me set this project in context. One of the defining problems of twentieth-century philosophy of language was the relation between knowledge of the reference of a term, and the pattern of use that you make of the term: the inputs and outputs to propositions involving the term, the ways in which you verify or act on the basis of propositions involving the term.

4

introduction

The difficulty is this. There is a common-sense picture of the relation between knowledge of reference and pattern of use. On the common-sense picture, your knowledge of reference controls the pattern of use that you make of the term. You use the term the way you do because you know what it stands for. In the later Wittgenstein and in Quine, the problem is that they think the common-sense picture cannot be sustained. There is only the pattern of use: there is no such thing as a knowledge of reference which controls the pattern of use, and to which the pattern of use is responsible. In later Wittgenstein, the form the resulting problem takes is that the pattern of use now seems arbitrary, since it is no longer thought of as controlled by knowledge of reference. This is the issue he confronts in his discussion of rule-following. In Quine, the form the problem takes is that when we have only the pattern of use to consider, we find that it seems to leave underdetermined the ascription of meaning to the terms of a language. This is Quine's problem of the indeterminacy of translation. In the ensuing discussion, amazingly, the common-sense picture—that you use the word the way you do because you know what it stands for—is all but lost sight of. I am suggesting that, by thinking of knowledge of reference as explained by conscious attention to the object, we can see how to reinstate the commonsense picture. Just to illustrate again the fundamental point about conscious attention, suppose that you are sitting in a lecture and your mind wanders off a little, the lecture fails to grip. So you look around idly at the other people in the audience, your gaze resting now on this person, now on that. In effect, you highlight now one aspect of your experience, now another. In effect, you put a yellow highlighter now over one or another part of your visual experience, as you wonder about this or that person. Now suppose that as you sit there, your neighbour whispers in your ear, 'Who's that man there?' To understand the remark you need to know who he means. So you need to single out the right person visually. It really is conscious attention that matters here. If, as you listened to your neighbour, the neural circuitry underpinning visual awareness blinked out of operation, leaving your visuomotor circuitry intact, it could happen that your visuomotor system, remote from consciousness, managed to lock on to the right person, so that you could, to your surprise, point to the right person. Perhaps in some sense your finger might be said to know who was being referred to. But you would not know who was being referred to until normal service was resumed and you achieved experience of the person. Of course, in an ordinary case it can happen that I am consciously attending to, for example, one building, while you are talking about another one in front of us. In such a case I might still understand exactly what you are saying in your use of the demonstrative 'that building', because I

Introduction

5

am relying on my having consciously attended to the referent a moment ago. I shall mostly ignore such complications in what follows. Or again, it can happen that I understand you perfectly, even though I am not 'giving you my full attention', as we would ordinarily say, perhaps because I am simultaneously worrying about my debts. But that is consistent with my understanding of your remark depending on my having singled out the object in experience, even if I subsequently made little of your remark. Or again, it can happen that I am consciously attending to the building to which you are referring, even though I do not realize that it is the building to which you are referring. Conscious attention to the building is not in itself an understanding of your remark: I have to make a link between that conscious attention and the demonstrative you use. In the first two chapters I will begin on the characterization of that link, and pursue it through Chapters 6 and 7. Finally, there are subtle and delicate cases in which an understanding of the demonstrative may involve some combination of descriptive knowledge and conscious attention, cases such as those in which I refer to the cast shadow of an object I can see, a gleam of light on a car roof, or a reflection in a puddle. Demonstrative reference in such cases may involve thinking of the referent as dependent on a substantial thing. But I will set aside the exact analyses of such cases in vhat follows, concentrating on the primal case of reference to the substantial objects themselves. Summing up, there are three levels we can look at. There is the level of conceptual thought about your surroundings. There is the level of conscious attention to your surroundings, which is more primitive than the level of conceptual thought, and which explains your capacity for conceptual thought by providing you with knowledge of reference. And there is the level of the underlying information-processing systems, such as highlevel visual processing or the visuomotor system, which conscious attention can cause to swing into play. It is the liaison between conscious attention and the underlying information-processing sub-systems which provides you with your capacity to use the term, to verify propositions involving a term, or to act on the basis of such propositions. The problem which led both the later Wittgenstein and Quine to abandon the common-sense picture on which knowledge of reference controls the pattern of use that you make of a term was what we might call the derivation problem. They held that there was no way in which the pattern of use of a term could be derived from knowledge of the reference of the term. So Wittgenstein spoke about the lack of any blueprint from which we could derive knowledge of how to use a term, and Quine spoke of the myth of meaning laid up in a museum from which a pattern of use could be derived. But by focusing on the liaisons between conscious attention and

6

Introduction

the underlying information-processing involved in verifying or acting on the basis of propositions, we can see how to solve the derivation problem, reinstating the common-sense picture of use as controlled by knowledge of reference. The basic parallel is between the way in which conscious attention to an object can control the information-processing involved in acting on that object, or verifying facts about that object, and the way in which knowledge of the reference of a demonstrative term means that you can act intentionally on the object, or verify demonstrative propositions about the object. This is what makes it possible to identify conscious attention to the object as what provides you with your knowledge of the reference of the demonstrative. But further to making remarks about its functional role, we have also to consider what conscious attention to an object intrinsically is, that it can constitute knowledge of reference. Conscious attention is not merely a subjective state. It is a relation between the subject and the thing experienced. So it is not exhausted by the liaisons between conscious attention and the underlying information-processing. Russell thought of acquaintance as a cognitive relation more primitive than thought about an object, which nonetheless, by reaching all the way to the object, made thought about the object possible. I will argue that this provides a model for the way in which we think of conscious attention to an object. It is a state more primitive than thought about the object, which nonetheless, by bringing the object itself into the subjective life of the thinker, makes it possible to think about that object.

1

Experiential Highlighting 1. Intuition and Explanation Suppose you say to me, 'What is that mountain over there?' To understand your question I have to know which mountain you are talking about. I can construct various descriptions that I might use to interpret your demonstrative, 'that mountain'. For example, there are 'the mountain she is looking at', 'the mountain she is asking me about', and so on. But ordinarily, I do not need to construct any such description. I have a more direct way of interpreting the demonstrative, 'that mountain'. I can interpret it simply by looking to see which thing you mean. Ordinarily, my knowledge of which thing you are talking about is provided by experience of the object. And it is not just having the mountain in my visual field that matters. I have to single the thing out visually, I have to see it as a figure against a background. Of course, grasp of a demonstrative like 'that mountain' does not mean that I have to sustain visual attention on the object continuously throughout the period during which I am thinking or talking about it. We can discuss 'that mountain' during a period in which my attention shifts around the scene. It remains that my understanding of the demonstrative depends on the act of visual attention. You might acknowledge that ordinarily we would use visual information to interpret the demonstrative, but question whether it has to be conscious. The idea of visual information that is not conscious is made vivid by cases of blindsight. A blindsight patient is one who has suffered damage to his primary visual cortex, as a result of which he has no awareness of objects in one half of his visual field. Nonetheless, when forced to guess about what is in the blind field, he may be reliably correct about, for example, the orientation, direction, and sort of the object in the blind field, perhaps to his own as well as our surprise (Weiskrantz 1986). So here we seem to have visual information in the absence of consciousness. Couldn't this subject use such visual information to achieve an understanding of a visual demonstrative? If the answer is that there is a problem because a blindsighted subject will not in fact have enough visual information, or the wrong sort of visual information, we could try supposing, as a thought

8

Experiential Highlighting

experiment, that we have a subject who has all the relevant visual information but is not yet conscious of the object in the blind field. (Cf. Block 1997 for a related notion of 'super-blindsight'.) Suppose that our blindseer can guess reliably at the properties of an object—say, a tree—in his blind field, and can act appropriately with respect to it: pointing in the right direction, avoiding walking into it, and so on. Why should we not say that he is able to understand the demonstrative 'that tree'? Of course, anyone has to agree that the blindsight patient may be able to construct descriptions which will allow him to give some interpretation or other of the demonstrative, 'that tree', descriptions such as 'the tree in my blind field'. The issue is whether the blindseer has the very same way of interpreting the demonstrative as the ordinary subject has. That is, the question is whether for the ordinary subject, consciousness of the object is not completely idle in an understanding of the demonstrative. In that case, the blindseer could have exactly the same understanding of the demonstrative as the ordinary subject has. One problem here is to explain what role experience could be playing in providing you with knowledge of the reference of the demonstrative. That is, even if it is compelling to common sense that experience is needed for an understanding of the demonstrative, we still need an explanation, a theoretical analysis, of why that should be so. What work could experience of the object be doing? Another, much simpler question is whether it can be made compelling to common sense that the blindseer does not have the same understanding of the demonstrative as is provided by experience of the object. Let me start with the simpler question. I think that the simplest way to grasp the common-sense difference between the blindseer and the ordinary subject is to consider an ordinary case in which you and I are sitting at a dinner table with a large number of people around and you make a remark to me about 'that woman'. There are a lot of people around; I can't yet visually single out which one you mean. So on anyone's account, I do not yet know which woman you are talking about. Suppose now that we add to the example. My visual experience remains as before: a sea of faces. I cannot consciously single out the person you mean. All I get consciously is the sea of faces. But now we add some of what the blindseer has. You refuse to give me any further clues as to which person you mean, but you say, Try to point to the woman I mean'. As first I protest that I can't do that, since I don't know who you're talking about, but I do try to point, and to my surprise you say I'm pointing right at the person you mean. Suppose now that my conscious experience remains a sea of faces, but we extend the reach of my reliable guessing so that it encompasses everything the blindseer can do. So I can make reliable guesses about what the person is eating, wearing, and so on, as well as

Experiential Highlighting

9

reaching and pointing appropriately. But so long as my conscious experience remains a sea of faces, there is an ordinary sense in which I do not know who you mean. The problem here does not have to do with whether I am reliable: we can suppose that I am quite reliable in my guesses and we establish this over a series of such cases. The point is rather that I do not know who you mean until I finally look at where my finger is pointing, or look to see who is wearing the clothes I described in my guesses. It is only when I have finally managed to single out the woman in my experience of the room, when it ceases to be a sea of faces and in my experience I focus on that person, that I would ordinarily be said to know who was being referred to. So it does seem to be compelling to common sense that conscious attention to the object is needed for an understanding of the demonstrative. If common sense is right about this, then the problem is to achieve a theoretical understanding of why that should be so. In some contexts—though not, I think, the present one—the importance of visual attention has to do with the sheer quantity of information you are receiving about the thing. You receive much more information about an object whose physical image is focused on the relatively small part of the retina called the fovea than you do about an object whose image falls on some more peripheral part of the retina, just because of the mass and type of nerve-endings packed in to the fovea. So sometimes attention matters because it can involve foveating the object, hence receiving more information about it. But this is not the explanation of the importance of visual attention for knowledge of reference. We have to resist the analysis that says: 'I know which mountain you are talking about only when I have foveated the mountain, because only then do I have enough visual information about it to know which thing you are talking about'. Sheer quantity of information is not to the point here. Since Helmholtz 1866/1925, psychologists have distinguished between overt and covert shifts of visual attention. An overt shift of attention involves movement of the head, eyes, or body, generally to bring the thing into focus on the fovea. But it is possible to shift visual attention covertly, without movement of the head, eyes, or body. You can shift visual attention around even though your eyes hold steady on a particular fixation point (cf. e.g. Posner 1988). If you say to me, 'Don't look now, but that man over there seems to recognize you', I may exactly maintain fixation on my wine-glass, but look at him, as we say, 'out of the corner of my eye'. Even though I will not get a mass of visual information in this way, I may still manage to single him out visually to a sufficient extent that I know to which man you are referring. ' In any case, an appeal to the mere quantity of information being received about an object could hardly be what explains why experience of the object plays a role in knowledge of the reference of a demonstrative,

10

Experiential Highlighting

since you could in principle receive quite a lot of information about the thing without experiencing it. So how are we to characterize the role of experience? This is the question that will occupy us through the whole book. But for preliminary orientation, it may be helpful to indicate the direction of reply. I think that what explains the role of conscious attention here is the combination of two points. First, there is what I will call the relational character of experience of the object. So long as we do not analyse experience of the object as a matter of the object causing some experiential effect in you, we can regard experience as making the object itself, the categorical thing, available to the subject. Experience of the object makes the object itself, rather merely some sensory effect of the object, available to the subject. Secondly, there is the functional role of conscious attention. Suppose that you have a complex scene before you—say, a number of people you have never met before. As you look over the throng, you attend now to one, now to another face in the crowd. What does this experiential highlighting of one rather than another person come to? It affects the functional role of your experience of that person. It means that you are in a position to keep track of that person deliberately over time, you are in a position to answer questions about that person on the basis of vision, and you are now able to act with respect to that person. In an ordinary situation, until you highlighted that person in experience, you could have done none of those things. Both of these points need some explanation and defence. We also need an account of the relation between these two points: I will argue that this is provided by the notion of a 'way' of attending to the object, which is both strongly relational, being individuated in terms of the object in question, and needed in an account of functional role. I will discuss this point in Chapter 5. In Chapter 6, I will set out the first point, the relational character of experience. I will pursue the ramifications of the relational character of experience through Chapters 7-12. In Chapters 1-4 I will be principally concerned with the functional role of conscious attention, to which I now turn.

2. Conscious Attention I have said that conscious attention to an object, the highlighting of your experience of that thing, affects the functional role of your experience of the object. Having once consciously focused on the object, you are now in a position to keep track of it deliberately, to answer questions about it, and

Experiential Highlighting

11

to act on it. But how exactly can it happen that your experience of the object has this functional role? Take, for example, your ability to answer questions about the object. Do you, as it were, somehow read off the answers from the intrinsic nature of your experience of the object? Or is some further process at work? Let me contrast two different types of explanation you might give of your verbal report: A. 'I say it's blue, because it looks blue.' B. 'I say it's blue, because the cell-firing in V4 is registering blue at that location.' In discussing these contrasting explanations, I do not mean to be appealing to anything idiosyncratic about colours and colour experience, as opposed for example to shapes and shape experience. I could equally well work with the contrast: Al. 'I say it's square, because it looks square.' B1. 'I say it's square, because the cell-firing in V3 is registering squareness at that location.' I use colour only because it is a good example of a visible characteristic of a demonstrated object. V4 and V3 are areas of the visual cortex thought to be involved in, respectively, the processing of colour and the processing of form information. Filling out an explanation of type B or Bl might be held to involve emphasizing neural areas upstream or downstream of V4 or V3; for present purposes this point is not critical. I think the first thing we have to say is that both types of explanation are, on the face of it, legitimate. Of course, in a particular case they could be mistaken. Perhaps the object doesn't actually look blue, but you made a mistake anyway. Or perhaps it was cell-firing in some other area that caused your verbal report. But the styles of explanation seem right. Explanations of type A (or Al) are most familiar to common sense; it seems, to common sense, absolutely compelling that such explanations are often correct. They are the kinds of explanation you might give when asked your reasons for making a particular report. In contrast, explanations in the style of B are not in general readily known to the person making a verbal report. But scientific accounts of vision depend very heavily on the legitimacy of explanations of this type. The picture of verbal report as caused by visual information-processing in various specialized pathways is fundamental to much of the experimental work on the visual pathways. I will give some examples in a moment. Information-processing explanations challenge the unity of the philosophers' notion of a representational state. Philosophers sometimes think of beliefs and desires as representational and suppose that it will be

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possible to explain all other representational notions in terms of their relations to beliefs and desires. However, the representational states postulated in information-processing explanations are not themselves beliefs and desires, nor does it seem possible to explain their contents in terms of their relations to beliefs and desires. According to Chomsky 1976, we do have a unitary notion of 'representational state' which covers both ordinary beliefs and the states involved in, for example, analysing the grammatical structure of a heard sentence. The difference is only that some of these states—in particular, ordinary beliefs and desires—are accessible to consciousness, while others, such as those postulated by linguists, are not accessible to consciousness. But, according to Chomsky, the distinction between representational states accessible to consciousness and those not accessible to consciousness is of no particular theoretical interest. An alternative reaction is provided by Searle 1995. According to Searle, there is only one notion of representation and it is constitutively linked to consciousness; there are only the ordinary beliefs and desires, of which we can in principle become aware, and it does not really make sense to talk in terms of other kinds of representational state. On this view, informationprocessing explanations are problematic, for we can have intentionality only on the part of states which are in principle accessible to consciousness. The cautious view, though, is that we have (at least) two different types of representation (Davies 1995). On the one hand, there are the conceptual contents of ordinary beliefs and desires, to which consciousness may constitutively attach. On the other hand, there are the non-conceptual contents of information-processing states. The present point is about the relation between non-conceptual, information-processing content, and a third element: the content of conscious attention. I began with the remark that conscious attention is what explains our grasp of a particular type of conceptual content, namely, demonstrative content. We are now looking at the relation between conscious attention and information-processing content. If you are asked the question,'What colour is that block?', you must, to understand the question, consciously attend to the block. As we saw, it seems compelling that it is in virtue of your conscious attention to the block that you know which thing is in question. If you are to verify the proposition, That block is blue', it is not enough merely that there be appropriate cell-firing in visual area V4. After all, at any one moment, as you look at a complex scene, there will be many objects of various colours in your visual field. So there will be a lot of cells in V4 firing in response to the different colours in the scene. Your verbal response, 'That block is blue', has to be caused by just the right cell-firings; it has to be caused by exactly the cells which are firing as a consequence of that particular block

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having the colour it does. So these particular cells have to be selected and used to affect the verbal response. What causes there to be that connection? I want to propose that what causes there to be that connection, between your verbal response and the cell-firing, is your conscious attention to the object. 3. The Causal Hypothesis Let me state this Causal Hypothesis formally: The Causal Hypothesis: When, on the basis of vision, you answer the question, 'Is that thing F?', what causes the selection of the relevant information to control your verbal response is your conscious attention to the thing referred to. What is the argument for this causal hypothesis? If you were not consciously attending to just that object, then just those cells would not be affecting your verbal response. Had you been consciously attending to a different object, a different set of cells would have been affecting your verbal response. And so long as you were to be looking at just that object, in just that context, it still would have been just those cells that affected your verbal response. These counterfactuals do not, in themselves, constitute the truth of the causal claim. But the counterfactuals are plainly true; otherwise, your verbal responses would not bear any relation to the objects of your conscious attention, and the visual verification of propositions about demonstrated objects would be simply impossible. Moreover, the causal thesis explains why those counterfactuals are true. There are two complementary lines of objection that you might have to this causal thesis. First, you might accept that there is a serious question: 'How does it come about that the firing of cells in V4 is connected to your verbal response?' But, you might say, the cause of there being this connection is not conscious attention to the relevant object. It is, rather, a further information-processing mechanism. To this objection we must immediately concede that there are illuminating information-processing models of the executive control of mental processes, and that the errors made in controlling which mental operations to perform can show that the causation of a verbal response by cell-firing in the visual cortex, under the guidance of conscious attention, is not a simple matter and may well be mediated by a number of small-scale mechanisms concerned with, for example, sequencing the various tasks the agent may be performing in roughly the same period (cf. Norman and Shallice 1986; Shallice 1988; Monsell 1996). But at the highest level of determining the objectives of the subject, there simply

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is no alternative to appealing to the beliefs and intentions of the agent, and that includes the demonstrative beliefs and intentions of the agent. If we were blocked from appealing to the agent's intentions, we would simply have no idea where to begin in giving a model of control of the agent's mental operations. But what I have just been arguing is that an appeal to the agent's demonstrative intentions requires us to appeal to the agent's conscious attention to objects; we cannot acknowledge a role for intention, in the control of mental operations, without thereby acknowledging a role for conscious attention. We may have to appeal to the deepest aspects of an agent's personal life in explaining why his conscious attention has just the focus that it does, and we have no way of recasting this causal-explanatory work in information-processing terms. It can, of course, happen that people make verbal responses whose causation by visual processing is not under the control of conscious attention. That is exactly what happens in cases of blindsight, when the patient is reliably accurate in his verbal reports about the contents of the blind field. But the mere fact that such a thing occurs can hardly show that this is what always occurs. Conscious attention to objects can make a difference nonetheless. You might wonder whether it would not be possible for a sufficiently ingenious experimenter to establish that the onset time of selection of the relevant visual information to control verbal report is prior to conscious attention being given to the object. (That is, you might wonder whether the Causal Hypothesis is not vulnerable to a result in the style of Libet 1985, 1999.) But causation here is not a matter of onset time only; as Libet has emphasized, such a difference in onset time would not be enough to establish epiphenomenalism. Even such a point about onset time, were it to be tested, would be consistent with the view that conscious attention to the object is essential in sustaining and maintaining the selection of information for verbal report, in an ordinary case. Another way to put the point is to note that when you say to someone, 'What colour is that block?', it ordinarily matters whether or not they understand the question; in particular, whether they know which thing you are talking about. The question, for someone who proposes that all the causal-explanatory work in controlling their verbal response is achieved at the information-processing level, is whether we can give an account, in purely information-processing terms, of the distinction between knowing which thing is referred to by the demonstrative and not knowing which thing is referred to by the demonstrative. As we saw, common sense draws that distinction by asking whether the subject has consciously singled out the reference of the demonstrative. We have simply no way of getting the effect of that distinction in purely information-processing terms.

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This line of objection to the causal thesis I am proposing—the thesis that it is conscious attention to the object that brings it about that your verbal response is controlled by the relevant cell-firing in V4—would fit with the view that conscious attention is epiphenomenal, that it is always causally idle. On this view, our ordinary demonstrative beliefs and intentions simply have no effect on our actions or on the world. But the line of objection would also fit with a less extreme position. On this view, conscious attention is not epiphenomenal, it does have a causal-explanatory role to play, but its causal-explanatory role is confined to the 'space of reasons'. On this view, conscious attention to just that object can be what brings it about that your verbal response to the question, 'What colour is that block?', is controlled by just the right aspect of your conscious experience. On this view, conscious attention to the block can be what brings it about that your saying, That block is blue', was caused by your experiencing just that block, rather than anything else, as blue. So the correctness of an explanation of type B can be underwritten by the focus of your conscious attention. But, you might argue, the correctness of an explanation of type A can never be underwritten by the focus of your conscious attention. Supposing that it can be so underwritten involves, on this view, an illegitimate crossing of explanatory levels, moving from one explanatory level— 'the space of reasons'—to another—the level of information-processing psychology. However, scientific accounts of vision are already heavily committed to level-crossing. For example, the appeal to information-processing to explain verbal reports is already a level-crossing in that sense: it appeals to information-processing to explain the allegedly 'space of reasons' phenomenon of verbal judgement. Moreover, once we accept the legitimacy of B-type explanations at all, it is hard to see how conscious attention could play a role in bringing it about that your verbal report is controlled by a particular aspect of your conscious experience, except by bringing it about that your verbal response is controlled by an appropriate aspect of the underlying information-processing. It is probably a mistake to suppose that there is any competition between type-A explanations and type-B explanations, even though there is this level-crossing. Suppose you consider the relation between a type-B explanation and the remark: I say it's square, because it is square. This remark is plainly consistent with a type-B explanation; we are being given descriptions of different aspects of a single causal process. The only problem with this explanatory remark is that it provides no clue as to just how the squareness of the object is affecting you; that is, through which sensory channel. So we might say:

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I say it's square, because it's visibly square. And this also is plainly consistent with a type-B explanation. And suppose we now say, more cautiously: I say it's square, either because it's visibly square, or because it's just as if it's visibly square, This gives one way of interpreting a type-A explanation. On this interpretation, 'a looks F' can be glossed as: 'Either a is visibly F, or it's just as if a is visibly F'. So on this interpretation of type-A explanations they are plainly consistent with type-B explanations, describing different aspects of the same causal process.

4. The Role of Location What I am proposing, then, is that your knowledge of the reference of a demonstrative is provided by your conscious attention to the object referred to; and that your knowledge of reference thus supplied is what causes particular information-processing procedures to be used to verify propositions involving the demonstrative. Without yet going into the details—we will look at the details in Chapter 3—it seems straight off that the situation with respect to action on the basis of a demonstrative proposition will be similar. Conscious attention will be what causes the right information-processing systems to be selected to allow you to act on the basis of a demonstrative proposition. The pattern of use that you make of the demonstrative is explained by your knowledge of its reference. Incidentally, it is not just that conscious attention to the object will cause the right information-processing content to be selected. Conscious attention also defines the objective of the information-processing: it determines which object the information-processing has as its target. I want now to bring out how this approach lets us determine the sense of the demonstrative: that is, the way in which the object is given to you in consciously attending to it. Suppose for the moment that the causal hypothesis is correct, that it is your conscious attention to the object that brings it about that your prepositional judgement causally depends on a particular set of cell-firings, carrying a particular piece of information about the object. The next thing to understand is how there can be this causal-explanatory relation between the conscious identification of the object and the selection of particular information. How exactly does your identification of an object, at the level of your subjective life, bear on the selection of information for further pro-

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cessing? That is, what is it about your identification of the object at the level of your subjective life that causes the selection of just the right underlying information to control your verbal reports? The very fact that this question demands an answer defines a sense in which there has to be a commensurability between content at the information-processing level and the content of consciousness. There is commensurability in the sense that there are causal-explanatory relations between the two types of content. One familiar way in which it is generally supposed that there is commensurability between the two types of content is that it is often supposed that a scientific account of vision could eventually explain why we have the kinds of visual experience that we do: for example, that the experience of redness may be causally explained in part by the fact that various cell-firings are registering the presence of redness (cf. Marr 1982). This does not presuppose that it is the very same type of content at both levels, but it does demand a commensurability between them. A parallel commensurability is presupposed between information-processing content and the conceptual content of verbal report, when we assume that what is happening at the information-processing level can explain our making the verbal reports that we do. I am not here concerned with this bottom-up commensurability, in which the content of conscious experience is explained in terms of information-processing content. The issue that concerns me is, as it were, a top-down commensurability: to explain in detail just how conscious attention to an object can identify the thing, so that, at the informationprocessing level, just the right information is selected to control your verbal reports. How in detail does conscious attention to an object serve to single out the right information to control verbal report and action? Suppose we consider a minimalist response to this question. The minimalist would say that, at the conscious level, the object is identified demonstratively, as 'that block', for example, and that at the information-processing level, the object is again identified demonstratively, as 'that block'. You might protest that these have to be quite different types of demonstrative, since the subjective 'that block' has to be grasped by the use of conscious attention, whereas there is no similar role for consciousness at the information-processing level. But we are already acknowledging that there must be commensurability between different types of content, and so we should allow that there could in principle be causal-explanatory relations between different types of demonstrative content. You might also protest, as against the minimalist, that we have as yet no account of how demonstratives are individuated, so we do not yet have any analysis of when we have commensurability between demonstratives at the two levels; but a minimalist may simply reject the demand for an account of individuation and take this

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commensurability to be a primitive phenomenon. The most radical problem for minimalism is, rather, that we cannot assume that the relevant information-processing contents are to be specified using singular terms at all. The point here is that visual processing is carried out in specialized processing streams, and there is no such thing as the single stream in which all the information about any single object is carried (Zeki 1993). The way in which the object is identified at the level of visual attention has to be capable of singling out information from any of a range of specialized processing streams, to control verbal report. The evidence from physiology and from cognitive studies is that location is what is used in cross-referencing visual processing streams (Zeki 1993). In each specialized processing stream, determining colour, shape, or movement, for example, the processing generally carries information also about the locations of the colour, shape, or movement; so that if it matters whether a colour and shape discovered in different processing streams relate to the same object, a first approximation to the answer will be provided by asking whether the colour and shape are at the same place. If this is right, then when you consciously attend to the object, you will be able to single out which information streams are relevant to verification and action on the object so long as your experience identifies the object as the thing at a particular location. Of course, there is more to the singling out of the relevant information than merely location. If you are verifying or acting on the basis of propositions about a glass which is currently being clasped in a hand, the parts of the glass may be no closer to each other than they are to the parts of the hand. So location alone would not be enough to select the information relating just to the glass. There must also be some use of something like traditional Gestalt principles of grouping (cf. e.g. Palmer and Rock 1994; Prinzmetal 1995). As we shall see, it has been a traditional insight, shared by Moore 1962 and Evans 1982, and carefully expounded by David Kaplan 1989b from Michael Bennett, that the senses of demonstratives involve the locations of the objects seen. But the problem for the traditional insight has always been that articulating it seems to involve ascribing something like a descriptive sense to the demonstrative. It seems to involve supposing that the demonstrative 'that box' must mean something like 'the box at that place'. And this proposal always runs into the problem that you may in vision be having an illusion about where the thing is, and yet be demonstrating it successfully. The proposal I am making is that the sense of the demonstrative is indeed given by the seen location of the object, but the role of the experienced location of the object is not to provide a descriptive identification of it. It is, rather, to organize the information-processing

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procedures that you use to verify, and to act on the basis of, judgements involving the demonstrative. It is entirely possible that the experienced location of the object should succeed in playing that role, so that you manage to have just the right information-processing procedures swinging into play to allow you to verify and to act with respect to the object, even though you are under an illusion about where it is. So we can individuate demonstrative senses by the seen locations of the objects, without supposing that location has to be providing a descriptive identification of the thing. And we have to keep in mind that there will be a role also for something like Gestalt organizing principles in individuating the senses of demonstratives. 5. The Empirical Evidence for the Role of Location The question I have been asking is, how does the selection of an object, at the level of conscious experience, affect the selection of information to control verbal report? There has to be something general-purpose about the selection of an object at the level of conscious attention. By singling out an object in experience, you enable yourself to answer any of a range of questions about its visible characteristics—not just its colour and shape, but its location, movement, orientation, and so on. So how is it that your singling out of an object in experience can have this general-purpose character? We could, in principle, use any of a wide range of strategies. For example, we could in principle use colour as a selection cue. Suppose that you are looking in the window of a shop selling jerseys and sweaters. The big display window is a mass of jerseys, all different shapes, colours, and sizes, from floor to ceiling; both the back of the display and the two side wings seeming to engulf you in jerseys. As you look, you focus now on one, now on another. Perhaps you spend some time comparing two. It is easy to imagine that you might select now one jersey, now another, to dwell on visually. What is not so easy to imagine is that you might simultaneously select all and only the red jerseys, from different parts of the display; that you might simultaneously highlight in experience all these different jerseys at their different places. It is not that there is a contradiction in supposing that someone might be able to do this. There is no a priori reason why we could not operate in that way. If we did, then at the level of conscious experience, we would simply highlight redness, and at the informationprocessing level, information from all the objects designated as red would be simultaneously selected. Certainly from a computational point of view we could construct a machine which, when given information about the

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shape, size, colour, and so on of targets at various places, could simultaneously select the information from all the targets labelled as red, for further processing, in parallel, simultaneously, on all of it. So why can't we do that? The obvious answer is that though we could indeed construct a machine which worked in that way, that is not, as matter of engineering fact, the way in which we work. We visually select targets on the basis of location, and in general we can give focused attention to only one location at a time. The evidence that this is in fact how human vision works, selecting information from objects on the basis of location, comes from a variety of experiments. Suppose, for example, that you are shown a display of nine letters, three of them red, three of them green, and three of them brown. You are asked to name one of the red letters, and as many of the others as you can. If it were possible for you to focus simultaneously on all the red letters in the display, then the simplest strategy would be for you to do that: read out all the red letters, then name as many of the green and brown as you could. In fact, though, Tsal and Lavie 1988 found that this was not what subjects did. Rather, having first named one red letter, subjects then typically went on to name other letters spatially adjacent to the red letter. This implies that there are two steps in focusing onto the initial target red letter: (a) find a location at which there is redness; (b) report the letter found at that location. To complete the task, you then (c) go on to report the letters at adjacent locations. . Tsal and Lavie were building on a finding by Snyder 1972, who asked his subjects to name the single red letter in a display of otherwise variously coloured letters. Looking at the mistakes people made in trying to do this when under time pressure, he found that observers tended to report one of the two immediate neighbours of the red letter on about 35 per cent of the trials on which mistakes were made. If errors had been equally likely to involve all positions, this should have happened on only 18 per cent of the trials. Again, it looks as though the strategy being used is to find the location of the redness, then report which letter is at that location. On this analysis, it should happen that you can accurately report which letter is the red one only when you can also accurately report the location of the letter. Nissen 1985 confirmed that this is indeed so. In his review of the literature on this point, Pashler writes: In summary, location is special in this sense: when an observer detects a target defined on other dimensions ranging from simple to relatively complex, this provides information about the location of the stimulus being detected. A simple metaphor conveys the essence of this idea: when someone reads out information from a channel selective for a particular target, this channel is labelled with at least rough location information. (Pashler 1998: 98-9)

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The force of the idea that location is a primary selection cue, as Pashler puts it (1998: 98), is illustrated by forced-choice tasks in which just one out of n possible targets is present, and your task is to say which one of the n targets is present on this occasion. In this task, you may also be asked about the location of the target. And if you get the location wrong, the probability that you are right about which target is present is close to 1/n; that is, you are at chance, you are just guessing (Shiffrin and Gardner 1972; Johnston and Pashler 1991). Suppose we accept that location is a primary selection cue. What are the implications of this for the Causal Hypothesis? What does it tell us about the way in which the experiential highlighting of an object can cause the selection of input information for further processing? What it all tends to show is that in experientially singling out an object, identification of the location of the object will enable the information relating to that location to be selected, for the control of verbal report. So if, at the level of experiential highlighting, you can identify the object by its location, this will enable the relevant information to be singled out to control your verbal reports about that object. And this is why location plays a special role in the way in which you identify the object at the level of conscious experience.

2 What is Knowledge of Reference? In this chapter, I want to set in broader philosophical context the observation that knowledge of the reference of a demonstrative is provided by conscious attention to the object. There is a connection between the notion of reference and the notion of truth. When you refer to an object and say something about it, whether or not what you say is true depends on whether what you have said is true of the object to which you have referred. So a term that stands for an object makes a contribution to determining whether a statement containing that term is true or false, by standing for that object. What exactly is the relation between knowledge of the reference of a singular term, such as a demonstrative, and your ability to verify, or find the implications of, propositions involving the demonstrative? Understanding this is fundamental to understanding the role of conscious attention. 1. Reference vs. Use

It often seems possible to formulate a hypothesis without knowing how to test it. A famous example in mathematics is the Goldbach Conjecture, that every even number is the sum of two primes. It certainly seems possible to understand this hypothesis, to know what it is for it to be true, without knowing how you would go about verifying or refuting it. In fact, it seems that to understand a proof of the conjecture you need to have mathematical concepts that go far beyond those you need simply in order to grasp the theorem itself. A similar point applies to hypotheses about the distant past. Take, for example, the view that among the Picts, succession to the kingship went through the line of the mother rather than the father, so that if the king died without children or siblings, his heir would have been the son of his mother's brother or sister, rather than the son of his father's brother or sister. This hypothesis is easy to formulate but hard to confirm or refute, and at the moment is still unresolved.

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Or again, a physicist may formulate a hypothesis without being able to confirm or refute it. You might conjecture that neutrinos spin clockwise when viewed from the direction in which they are going, for instance, without at all being able to verify it. Understanding the conjecture, knowing what it is for it to be true, is one thing, and knowing how to verify or refute it is another. There must presumably be some relation between the way in which you understand the hypothesis, and the way in which you set about verifying it. They are not simply unrelated. Your understanding of the hypothesis means that you know what it would be for the hypothesis to be true. And your knowledge of what it would be for the hypothesis to be true has to have some bearing on how you go about verifying or refuting it. A similar point applies to your knowledge of how to find the implications of a proposition—either its deductive implications for the truth of other propositions, or its significance for action. You could know what it is for the proposition to be true without yet having grasped its implications. But your knowledge of what it is for the proposition to be true must have some bearing on what you will take its implications to be. There are, I think, two types of relation we might expect to find here, between your knowledge of what it would be for the hypothesis to be true and your use of a particular way of verifying the hypothesis. First, your understanding of the hypothesis should be what causes your use of a particular method of verification or refutation. I will call this the Causal Link: The Causal Link: Knowledge of what it is for a hypothesis to be true is what causes your use of a particular way of verifying, or finding the implications of, that proposition. It is, though, not just that your use of the method of verification is caused by your understanding of the proposition. It ought also to be possible to view the use of a particular method of verification as being justified by your knowledge of what it would be for the proposition to be true. Your use of the method of verification has an objective, defined and grasped prior to the use of that method of verification. The objective is to find out whether the proposition is true. So it ought to be possible to view the method of verification as a way of meeting that objective. This is what I will call the Justification Thesis: The Justification Thesis: Knowledge of what it is for a hypothesis to be true is what justifies your use of a particular way of verifying (or finding the implications) of that proposition. Putting the Causal Link and the Justification Hypothesis together, we have what I will call the Classical View:

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What is Knowledge of Reference? The Classical View: Knowledge of what it is for a proposition to be true is what causes, and justifies, your use of particular ways of verifying, and finding the implications of, that proposition.

Before looking at the case of demonstratives, it may be helpful to look at a much simpler example of the Classical View. Perhaps the simplest and most striking illustration of the Classical View is provided by the classical account of prepositional logical constants, terms such as 'and', 'or', and so on; I will look at this case in Chapter 5. But we can also apply the classical picture to our understanding and use of so-called descriptive names. An example of a descriptive name is the name 'Elmo', used as shorthand for 'the oldest tree in this garden', For there to be such a thing as Elmo, there must, of course, be exactly one tree in this garden which is older than all the others in the garden. There will be procedural rules for the use of the name 'Elmo'. Some of these rules—the introduction rules—will specify when a proposition containing the name 'Elmo' has been verified. Other procedural rules—the elimination rules- -will specify the implications of propositions containing the name 'Elmo'. The introduction rules for 'Elmo' will include: Exactly one tree in this garden is oldest

Any tree in this garden which is oldest is F Elmo is F

This tells you how to verify a proposition of the form, 'Elmo is F': establish both that there is such a thing as Elmo, and that anything meeting the condition for being Elmo is F. The elimination rules will include: Elmo is F exactly one tree in this garden is oldest Elmo is F any tree in this garden which is oldest is F Given that Elmo is F, you can move to the conclusion that there is such a thing as Elmo: the first elimination rule above spells out the implication of there being such a thing as Elmo. The second elimination rule spells it out that if Elmo is F, you can conclude that anything meeting the condition for being Elmo is F. These are the procedural rules. On the Classical View, what causes and justifies your use of these ways of verifying and finding the implications of propositions involving the term 'Elmo' will be your knowledge of the reference of the term:

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'Elmo' refers to the oldest tree in this garden. By denning what has to be the case for a proposition involving the name 'Elmo' to be true, this statement of reference defines the objective at which the introduction rule aims, and allows you to determine what we should take to be the implications of a statement using the name. In that sense, it justifies the use of those introduction and elimination rules above. We do not need to suppose that reflective reasoning is involved at all in the causation of your pattern of use of the term by your knowledge of the reference of the term. Your pattern of use may simply be systematically causally dependent on your knowledge of reference. If you varied the reference of the term, you would consequently vary which procedural rules you took to be correct. How does this Classical View apply to perceptual demonstratives, terms such as 'that man' or 'that whale', referring to currently perceived objects? As we have seen, there is a strong intuitive link between our understanding of perceptual demonstratives and consciousness of objects. The link is that you have to be conscious of the object in order to understand a statement made using the demonstrative. Suppose you and I are standing side by side on an observation platform high in the sky. I am gripping the railing tightly and staring at my hands. You make a series of remarks about a building visible in the distance. Since I am listening, I can formulate a number of descriptions: 'the building you are looking at', 'the building with the golddomed roof, and so on. But I do not understand your use of the demonstrative, 'that building', until I finally stop focusing on my hands and look. G. E. Moore put the point succinctly when he said: 'the prop, is not understood until the thing in question is seen.' (Moore 1962: 158). You do not understand the demonstrative except by being conscious of the object; or rather, there is a distinctive way of understanding the demonstrative that is provided by your consciousness of the object. So there is a theoretical role to be played by the notion of consciousness of the object. It has to explain the ability to understand the demonstrative. The intuitive link is not just between reference to a perceived object and consciousness of it, but more specifically between reference to the object and conscious attention to it. To refer to the perceived object, it is not enough that I have it in my field of view. As I look over the scene, it is not enough that the gold-domed building be there somewhere in my visual field. I must separate it visually, as figure from ground, I must visually discriminate it from its surroundings. I have to attend to it. Knowledge of the reference of the demonstrative is what causes and justifies the use of particular procedures to verify and find the implications of propositions containing the demonstrative. Conscious attention to the

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object, I will argue, is what causes and justifies the use of particular procedures for verifying and finding the implications of propositions containing the demonstrative. Hence, knowledge of the reference of the demonstrative is provided by conscious attention to the object.

2. Two Examples: Action and Verification If knowledge of the reference of a demonstrative is provided by conscious attention to the object, then we have to think of conscious attention to the object as what causes and justifies our use of patterns of verification and ways of finding the implications of demonstrative propositions. Just to illustrate how this view should work, I will give two simple examples. One relates to the output from a demonstrative proposition, looking at the link between knowledge of the demonstrative and action. The second example relates to the input to a demonstrative proposition, looking at the relation between knowledge of the demonstrative and verification of a demonstrative proposition. Briefly, the two examples I am about to describe are: (1) Catching a cricket ball. In this case, my conscious attention to the ball is what causes and justifies my use of particular procedures to catch that particular ball. (2) Finding whether one thing is enclosed by another. In this case, my conscious attention to an 'X' is what causes and justifies the use of a particular information-processing routine to verify the proposition that that particular 'X' is enclosed. In both these cases, computational processing is involved. I myself may not be aware of which computational procedures are being used; but it is my conscious attention to the object that defines the objective of the computation. It is in that sense that conscious attention justifies the use of the computational procedure: the use of the computational procedure can be justified or criticized by reference to the objective defined for the procedure by conscious attention. You might accept that there are information-processing systems in the human being, but suppose that they are insulated from the kinds of psychological phenomena familiar to common sense. You might believe that the dynamics of the two systems, information-processing and ordinary consciousness, are independent. But that would be a mistake. Which information-processing we perform is not somehow isolated from the explicit objectives that we have, the tasks that we want to carry out. Which

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information we process, and how, depends in part on what we are up to, what our objectives are. (1)1 turn to our first example, the fielder in a game of cricket trying to catch a falling ball. Suppose that you have to catch a ball. You can do this without being able to say how you do it. But to do it you have to be selecting information from the moving ball, and performing operations upon that information, if you are to catch the thing otherwise than by accident. According to McLeod and Dienes 1996, skilled fielders do this by finding a speed that will keep the acceleration of the tangent of the angle of elevation of gaze to the ball at 0. Even a skilled fielder, though, does not simultaneously perform this computation for every airborne object he sees. This information-processing is outside your conscious life; but it is being performed in the service of the goal you explicitly have, to catch 'that ball'— demonstratively identified. So then there is a question how this is done, how our information-processing capacities get harnessed to our conscious objectives. The key notion that we need, in explaining this connection, is attention. If you are to act intentionally with respect to the moving ball, you have to attend to it perceptually. And that conscious attention is what causes the selection of information from the ball, and selection of which operations to perform upon it. To sum up: if you are to act intentionally on an object, you must consciously attend to it, in the common-sense use of the term; but that act of attention must also cause the selection of suitable information for processing, and suitable processes to operate on it, if the information-processing of which you are capable really is to be harnessed to your objectives. The concept of conscious attention thus plays a role here in connecting our psychology, at the level described by common sense, with the information-processing described by psychologists. (2) My second example of the Classical View in operation relates not to action but to the verification of a demonstrative proposition. There are bottom-up processes involved in perception, which provide us with some basic information, and then there are top-down visual processes, selected according to the task in hand, applied to some portion of that basic information. So when you look at the scene before you, there are, as it were, many different visual questions you can ask. Is this object inside that one? Are the chairs arranged in a circle? Will you be able to cross the room by taking the direct route to the door? To answer these questions, you just have to look. But this kind of visual interrogation of the scene involves the exercise of visual skills, top-down processes that are selected by your decision to ask this question rather than that.

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Suppose you are shown a diagram with a figure containing a number of loops and an 'X', and you have to determine whether the 'X' is enclosed by the boundaries of the figure. In some cases this will be hard and in some cases it will be easy, but you are always exercising a visual skill. How are we to think of this visual skill? One proposal—from Ullman 1996—is that we think of the operation as involving a kind of 'colouring' process, so that from a given starting point, such as the 'X', there can be a spread of activation to neighbouring places, which stops when a discontinuity is encountered. If that process terminates, then the 'X' is enclosed. Otherwise, the 'X' is not enclosed. This kind of information-processing is not something of which we are conscious, but it can be elaborated to give an explanation of which cases we find easy and which we do not (Ullman 1984,1996). This processing involves the exercise of conscious attention. First, you have to select which place to begin from, you have to decide that the place of 'that "X"'—demonstratively identified—will be where you start. And secondly, you have to select which operation to apply to that place; you have to select the 'colouring' operation. There is no possibility of doing the whole thing without any selection; it would entirely defeat the purpose to try to apply the 'colouring' operation to all perceived places simultaneously, for example. Ullman suggests that this is a basic top-down attentional skill, one of a handful of basic routines that can be applied to the bottomup contents of perception in various combinations, for various purposes. These purposes are partly defined by the conscious attention of the subject. The structure of the view we have reached is that knowledge of the reference of a demonstrative is provided by conscious attention to the object. And conscious attention to the object is what causes and justifies the use of information-processing routines in acting on the basis of demonstrative thoughts about the thing, and it is what causes and justifies the use of information-processing routines in verifying propositions about that thing.

3. The Double Use of Feature Maps The Classical View demands that we keep knowledge of the reference of a term distinct from the use of ways of verifying that the object has particular properties. They have to be distinct, because the knowledge of reference has to cause and justify the use of methods of verification. It seems, though, particularly hard to keep knowledge of reference separate from method of verification in the case of demonstratives referring to perceived

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objects. The reason is that you can hardly have conscious experience of the object without already having, in some sense, verified its possession of various properties. It does not make sense to suppose that you could consciously attend to an object without being aware of it as having certain properties of shape, colour, and so on. You might therefore argue that the kind of high-level processing involved in finding whether one object is enclosed by another, which we discussed in the last section, is quite a special case. To verify that the 'X' is enclosed, after all, you will have to first identify the 'X'. And, you might argue, that will already involve you in having verified its possession of simple sensory properties, such as shape, size, and colour. (By a 'sensory property' I do not mean a 'secondary quality' in the traditional philosophical sense, but one of the properties used as primitive by the visual system.) So, you might argue, the Classical View cannot be sustained for the relation between knowledge of the reference of a demonstrative and verification that the object has particular sensory properties. Knowledge of reference in this case does not cause and justify the use of particular methods of verification. Rather, those verifications had to be performed already in order for there to be knowledge of reference. To deal with this objection there is a distinction we need. This is the distinction between (1) Using an object's possession of a property to single it out visually, and

(2) Verifying a proposition to the effect that the object has that property. Verifying a proposition involves the use of your conceptual skills, whereas visually singling out an object is a more primitive phenomenon. You could use the fact that an object is moving in a particular way to separate it visually from its background, without having formulated any proposition about its movement and indeed without having any concepts of motion at all. Similarly, it is possible to use colour as one of the properties by which you visually define the object—it is one of the properties in virtue of which you can be said to be seeing an object at all—even though you have not verified the proposition that the object has that property, and even though you do not have colour concepts. The obvious example here is an animal which may entirely lack concepts, but be able to use colour vision in separating objects from their backgrounds. Although we have to distinguish these two phenomena, visual singlingout and the verification of propositions, there is a connection between them. But before coming to the connection, let me give one more

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illustration of the distinction. For you might wonder whether this distinction can be drawn in the case of people who do have concepts of objects. If you are capable of grasping demonstratives referring to physical objects, can you be using colour vision to discriminate the objects around you, even though you do not have colour concepts and so cannot be said to be verifying propositions about the colours of those objects? Plainly you can. An example of this phenomenon is provided by children, who have the ability to refer to perceived objects, on the basis of colour vision, in place long before they have any grasp of colour concepts. Children have unusual difficulty in learning colour words, even the four basic terms, 'blue', 'green', 'yellow', and 'red'. This is not because of any delay in the maturation of colour vision. Even four-month-olds can discriminate, match, and recognize the four basic colours, so there is no reason to suppose that they lack experience of colour. And the difficulty is not because of a delay in learning which words are colour words. At an early stage, children will reply to the question, 'What colour is it?', by producing a colour word, but they may use the colour words randomly, or perseverate in using the same word for all colours. The situation seems to be that, as Bornstein puts it in his review of the developmental literature, 'early in life, sensory and linguistic colour knowledge seem to coexist, but a proper map connecting names and perceptions is late in developing' (Bornstein 1985: 78). At an early stage, then, children do not yet have colour concepts. But since they have colour vision, they can use the colour of an object as one of the characteristics that differentiates it from its background; they can use colour as an objectdefining characteristic without yet being able to verify propositions about the colour of the object. So there is certainly a distinction between visually singling out an object by use of its sensory properties, and verifying propositions to the effect that it has those sensory properties. But as I said, there is also a connection between the two phenomena: (1) visual singling-out and (2) the verification of demonstrative propositions ascribing sensory properties to perceived objects. To see this, let us put our distinction in the context of a fundamental topic in vision science: the way in which the visual system solves the socalled Binding Problem. As I said earlier, there is much converging evidence that different properties of an object, such as colour, shape, motion, size, or orientation are processed in different processing streams (Zeld 1993). This means that the visual system has the problem of reassembling individual objects, as it were, from the results of these specialized processing streams. A specific colour and shape, for example, have to be put together as the colour and shape of a single object, just when they are the colour and shape of a single object. We do not have perception of an individual object until this Binding Problem has been solved, and various

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simple sensory properties have been put together as properties of a single object. What strategy could be used to solve the Binding Problem? If the visual processing streams contain at least implicit information about the locations of the features being found—just where in the environment a particular colour or shape is, for example—then there is one effective strategy available. Features found at the same location could be put together as features of a single object. So if, in one stream, redness is found at a particular location, and, in another stream, squareness is found at that place, then the redness and squareness would be put together, so that you have perception of a red square. Of course, this could not be the whole story about how the Binding Problem is solved, because spatially overlapping objects, such as a hand holding a cup of tea, can be seen as plainly distinct, despite the fact that the parts of one object are as close to the parts of the other object as they are to each other. So there must be more than location at work. But it is nonetheless possible that location is a fundamental parameter in the way vision solves the Binding Problem. We can think of the various specialised processing streams as constructing maps showing the locations of particular features, and binding as being, in the first instance, a matter of features from the same location being put together as features of the same object. Anne Treisman's primordial Feature Integration Theory held that there is in the visual system a 'master map' of locations, which is scanned by a window (variable in size) of attention (see e.g. Treisman 1988). When the window selects a particular location on the master map, the features currently found at that location on all the various specialized feature maps are selected, put together to constitute an 'object token', and compared to stored representations so that the object can be categorized. The basic picture illustrating this approach is Figure 1 (p. 32). Spatial attention in Treisman's sense involves the singling out of a single location on the master map of locations, so that all features at the selected location can be bound together as features of a single thing. There is no very evident reason to think that spatial attention in this sense must be a phenomenon of consciousness. (For a striking example of spatial attention without awareness, see Kentridge, Heywood, and Weiskrantz 1999; for further analysis of the type of attention required for binding, see Briand and Klein 1987.) This kind of spatial attention is a precondition of consciousness of the object. The features must be bound for there to be experience of the thing. But the spatial attention itself may be a relatively low-level phenomenon. The kind of low-level exercise of attention that Treisman's model argues is required for binding, contrasts with the kind of exercise of conscious attention that I am arguing is required for knowledge of the reference of a demonstrative.

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Fig. 1. Framework proposed to account for the role of selective attention in feature integration. (From Treisman 1988. Copyright 1988 by Lawrence Erlbaum Associates.)

I have been distinguishing between (1) the use of properties of an object to single it out visually, and (2) the use of conscious attention to verify a proposition about an object. In our present terms, the point is that there is a double use for the feature maps, processing in parallel in early vision. They do have a role in determining which objects are there in the vicinity. It is only by finding which features are present and where, that it is possible for those features to be bound together to form object representations. The formation of an object representation is needed if there is to be experience of the object at all. Consequently, the binding of features established in early processing is needed for there to be any understanding of demonstra-

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tives referring to the objects in the vicinity. The second use of the feature maps is in verifying propositions about the observational properties of perceived objects; and this, as we have seen, is a separate use. It is one thing to verify a proposition to the effect that an object has a particular property, and another thing to use the object's possession of that property to single it out visually. Experience of an object is the upshot of low-level attention to a particular location. But once you have experience of the object, you can now attend to it consciously, keep track of it over time, find out more about it, and act intentionally on it. What happens in this second use of feature maps? Here we see the connection between the two phenomena. At this stage, the subject can be assumed to be capable of demonstrative reference to the object. What the subject has to do, to verify the proposition that the object has a certain colour, is to make that second use of a feature map in the right way. The right location has to be identified so that the verification of the judgement can be sensitive to which feature is represented as being at that location. This means that in demonstrative reference, the perceived location of the object is not simply a ladder that we throw away; it is not simply a feature of low-level processing which, although used in binding, is not itself registered in the way in which you experience the object. For the way in which you experience the object has to retain the capacity to single out the correct location, at the level of the feature map, when you attempt to verify the proposition. If your grasp of the demonstrative is to be capable of causing and justifying your use of feature maps to verify propositions about the observational properties of the object, then your grasp of the demonstrative must include information about the location of the thing. Hence, your experience of the object must include information about the location of the thing. This distinction between two uses of feature maps applies to the analysis of the kinds of experimental findings I discussed in Chapter 1, section 5. Consider, for example, Nissen's finding (Nissen 1985). Subjects were instructed to report the shape of, say, the red target. Nissen's finding was that subjects could give an accurate report of the shape of a target identified by its colour only if they could incidentally give correct reports of the location of the target. Her interpretation of the result is that subjects, in order to answer the question, consult the kind of feature map described by Treisman, and use the location of the target to identify the information relating to it in different processing streams. But then this is exactly an example of the kind of second use of feature maps that I am describing. We are not here dealing with the kind of low-level exercise of attention involved in the initial binding of features in ordinary perception, but a conscious attempt by the subject to find the red thing and then verify a

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proposition about its shape. (For more material relevant to the distinction between types of attention here, see Briand and Klein 1987 and Briand 1998). To sum up, it seems that we can sustain the Classical View, even when it is applied to the relation between knowledge of the reference of a demonstrative and verification of the most basic observable properties of the object. Even in this case, it can be your knowledge of the reference of the term, supplied by your conscious attention to the object, that causes and justifies the use of particular information-processing procedures—the second use of feature maps—to verify propositions about these observable properties of the thing. So we can continue to think of demonstrative reference on the Classical View. Your knowledge of the reference of the demonstrative is constituted by your conscious attention to the object itself. And this conscious attention to the object is what causes, and justifies, the use of particular information-processing procedures, reaching down to the feature maps, to verify demonstrative propositions about that object. (In this section, we have in effect recapitulated the argument of Chapter 1 from a slightly different perspective.)

4. Formally Describing the Use of a Demonstrative At this point we can be somewhat more explicit about the parallel between the Classical View as it applies to demonstratives and the Classical View as it applies to logical constants or descriptive names. We can try to formulate introduction and elimination rules for perceptual demonstratives to characterize their use, just as we use introduction and elimination rules to characterize the use of descriptive names. The empirical argument I have been giving is this. Suppose you are asked to verify a proposition about whether a demonstrated object in your visual field has a certain characteristic. Suppose, for example, that you are asked to verify whether that red object is round. The empirical argument is that in fact this involves you in first, determining the location of that red thing, then, second, determining whether there is roundness at that location. This suggests that the introduction rule for a perceptual demonstrative would typically be something like this: FEATURE MAP: Roundnesss at position p That figure is round However, the situation is actually more complicated than this. For the evidence suggests that visual attention can be allocated to objects rather than

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to locations. This is not inconsistent with the evidence that location is fundamental as a selection criterion, because objects are individuated partly by their locations. But the point is that location is not all that binds together an object. The kind of evidence that shows that visual attention can be allocated to objects rather than to locations is this. Suppose you have two figures, spatially overlapping and each continuously changing shape. People can track one of the figures, apparently to the exclusion of the other overlapping figure (Neisser and Becklen 1975). Or again, people are better—faster and more accurate—at judging two attributes of a single object than at judging two attributes of different objects (Duncan 1984). Again, suppose subjects are set the task of responding to a central object, while ignoring an object beside it. Interference from the irrelevant object can be increased when it and the target are grouped by Gestalt principles— for example, by moving in the same direction, or by having the same colour (Driver and Baylis 1989; Baylis and Driver 1992). So we ought to think in terms not of simple locations, but of 'visual objects', which will be individuated by some combination of (a) specific Gestalt principles, such as boundedness, sameness of colour, or common motion, and (b) location. So the kind of introduction rule we want is this: FEATURE MAP: Roundnesss at visual object X That figure is round Isn't 'visual object X'just a notational variant of 'that figure'? No, because at the input stage here we are still at a level of content more primitive than demonstrative content: individuation by Gestalt principles plus location is not yet conceptual demonstration of an object. We are talking only about a way of cross-referencing information in separate processing streams which does in fact relate to the same object, not about a level of representation at which we already have reference to objects (Prinzmetal 1995). What would an elimination rule for a perceptual demonstrative look like? As a first shot we could conjecture that the outputs of a perceptualdemonstrative judgement can be characterized in some such way as this: That cup contains water MOTOR SYSTEM: To reach water, move towards whatever is at position p, hand prehended thus and so On the classical approach I am recommending, the question of knowledge of reference comes up at the level at which we consider the justification that the subject has for the use of those procedures. This is where we have to appeal to the idea of conscious attention to the object. Which object you are consciously attending to is what causes you to use

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one information-processing procedure rather than another to verify the judgement. And it is the character of your conscious attention that causes you to use one information-processing procedure rather than another to find the implications of the judgement for action. Moreover, your conscious attention to the object does not merely cause your use of these information-processing procedures. It is also what you would have to appeal to in justifying the use of these information-processing procedures. It defines the point of these procedures, what the goal is of the computation. Suppose we go back to the descriptive name, 'Elmo', for which the introduction rule is: Exactly one tree in this garden is oldest

Any tree in this garden which is oldest is F Elmo is F

and the elimination rules are: Elmo is F exactly one tree in this garden is oldest Elmo is F any tree in this garden which is oldest is F And what causes and justifies your use of these ways of verifying and finding the implications of propositions involving the term 'Elmo' is your knowledge of the reference of the term: 'Elmo' refers to the oldest tree in this garden. What makes the relation between the reference axiom and the use of the term here seem so trivial is the easy commensurability between the reference axiom and the introduction and elimination rules. From your understanding of the phrase, 'the oldest tree in the garden', it is immediately evident why data to the effect that there is just one oldest tree in the garden, and that any oldest tree in the garden is F, for example, should be relevant to the verification of 'Elmo is F'. When we compare the case of the demonstrative, though, it is evident that we do not have the same immediate easy commensurability. Suppose we stick with the simplest introduction rule and the elimination rule already given: FEATURE MAP: Roundness at position p That cup is round

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That cup contains water MOTOR SYSTEM: To reach water, move towards whatever is at position p, hand prehended thus and so But conscious attention to the object has to validate the use of those introduction and elimination rules. In dealing with these specific proposed rules in particular, conscious attention to the object has to be of such a sort as to explain what the significance is of the location p. There has to be some commensurability between the way in which an object is identified at the level of feature maps and by the motor system, and the way in which the object is identified at the level of conscious attention. So what is the point of contact? I want to propose that it is found in what I will call the binding parameter. By the 'binding parameter', I mean the characteristic of the object that the visual system treats as distinctive of that object, and uses in binding together features as features of that thing. In Treisman's model, the binding parameter is a specific current location. A feature being perceived as currently at that location is what the system uses in binding it together with other features. Of course, in a more fully realistic model, the binding parameter will be more complex than simply location. It will include the aspects of Gestalt organization that are used in visually identifying that object. But location will evidently still be a component, just because we can see qualitatively identical objects simultaneously at different visual locations. For the moment, suppose we continue with the simplification that current location is the only binding parameter. Suppose now that conscious attention to the object—the highlighting of the object in visual experience—identifies the object as the object at a particular seen location. The identification of the target object as the thing at that location will then be enough for the visual system to know how to search the feature maps to find the shape, colour, or orientation of the thing. The binding parameter will then provide an address for the object, as it were—a way of identifying which object is in question, that can be used by the visual system when it has to verify or find how to act on the basis of propositions about that object. This way of putting it implies that at the level of conscious attention to the object, the very same frame of reference—the very same way of identifying locations—is being used as it is used by the initial feature maps in binding. But the commensurability between conscious attention and brain processing does not have to be achieved in just this simple way. Strictly speaking, all that is required is that there be a commensurability between the way in which locations are identified at the level of conscious attention and the way in which locations are identified at the information-processing

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level. All that is required is that conscious attention to the object should identify which thing is the target, in such a way that the informationprocessing sub-systems can, in one way or another, lock onto that thing in order to keep track of it over time, act effectively on the object, or verify propositions about it.

5. The Crick—Koch Hypothesis and an Analogy with Proper Names In thinking about the transactions between conscious attention to an object and the information-processing involved in verifying or acting on the basis of propositions about the object, it is sometimes helpful to consider an analogy. The analogy I have in mind is with the way in which gossip, or, more generally, information about individuals circulates in a community. All this information has to be sorted into bundles, so that each bundle contains information relating to just one individual; otherwise we would never know whether we were talking about the same or different people. The basic method we have for doing this is the use of proper names: we try to sort so that sameness of name is an indication that it is the same individual that is in question. That is not quite enough, though, since different people may have the same name. So we may add a tag. For example, if there are many different people named Williams, we might add tags like 'the milkman' or 'the mathematician'. Then the use of the name plus a tag gives us what we might call a bundling principle: a way of sorting together information as all relating to a single individual. Bundling principles will, then, play the same kind of role in organizing gossip as binding parameters play in the organization of visual information. It is worth remarking that bundling principles can do the work they do whether or not they are actually true of the object. It is perfectly coherent to suppose that Williams the mathematician might turn out not to be a mathematician at all, but a criminal who pretends to be engaged in mathematics. The tag, 'the mathematician', could still perfectly well play its role as a bundling principle. Similarly, Treisman could be right that location is a binding parameter, and you could be using the apparent location of an object perfectly well in sorting together all the visual information that relates to that object, whether or not the object is actually where it seems to be, rather than being reflected in a mirror or seen through a prism. So bundling principles or binding parameters can discharge their work without providing descriptive conditions which an object must meet in order to be the object to which you are referring. I think we can pursue this analogy in thinking about the point that there has to be a commensurability between the level of conscious attention and

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the level of visual information-processing. Suppose there are several different people called Reagan, and your informant Sally collects and provides you with information about each of them. So you stand to Sally somewhat as the level of conscious attention stands to the level of visual information-processing. Or rather—since the point of the analogy is not to encourage a homuncular picture of either conscious attention or visual information-processing, but to make it easier to think about the relations between different levels of content—the level of conscious attention stands to the level of information-processing somewhat as the content of your speech stands to the level of Sally's speech, in the analogy. Since there are several different people called Reagan, and Sally is collecting and providing you with information about each of them, Sally will be using tags like, 'the actor who was President of the U.S.A. in the early eighties' as bundling principles. Suppose that Sally gives you this information about all these various people, using the name 'Reagan'. You know that they all have the same name, so you are not in a position to use the name itself alone as a bundling principle. Now suppose that you want to have the following general capacities: (a) You want to be able to interrogate Sally for further information about any of the people about whom she is giving you information, and (b) You want to be able to instruct Sally to act on any one of the people about whom she is giving you information. To have these general capacities, you have to be able to identify the person in whom you are interested, for Sally's benefit. That is, your identification of the person about whom you wish to interrogate Sally has to be one that she can use to find the further information you have requested. Not just any way of uniquely identifying the thing you have in mind will do. Likewise, when you instruct Sally to act on a particular individual about whom she has given you information, you have to identify the individual in such a way that Sally can go about acting on that person; not just any way of uniquely identifying the thing will do. When you are interrogating Sally for further information about one of the Reagans, what you have to provide her with is a way of finding which bundle of information is relevant to your question. The simplest way would be to use the same tags that she uses. So you might say something like: 'How old is the Reagan who is an actor who was President in the early eighties?' But although that is the simplest procedure, it is not the only one that would work. You could identify the Reagan you mean as 'the one who was Governor of California', and that will work, even if it is not itself a tag

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that Sally uses as a tag, so long as she can work out that the Reagan who was Governor of California is the Reagan who was an actor that was President in the early eighties. So long as your identifier can be translated into a tag that Sally uses—and so long as Sally can make the translation— you will be in a position to interrogate her for further information about this person. A similar point applies, of course, to giving Sally instructions to act on one of the Reagans about whom she has given you information. She needs to have a way of identifying the target that she can use. So your way of saying which Reagan is in question has to be commensurable with the ways of identifying people that she uses in setting the parameters for her actions—in finding the address to which to write, for example. I am spelling out this analogy quite fully, partly because it may be helpful in reviewing the points that I have made so far. But I am also setting out the analogy because, as we shall see in a moment, it can be pursued to give a way of thinking about the bearing of the approach I am recommending on the Crick-Koch hypothesis (Crick and Koch 1990, 1992; see also Crick 1994). The Crick-Koch hypothesis is that the neural correlate of consciousness is to be found in the physiological mechanisms of binding. The Binding Problem was originally a physiological problem. Once it was observed that after the primary visual cortex, the visual system split into separate processing streams, it was apparent that neurons responding to different features of the same object may be anatomically separated. How, then, is it registered that these neurons are responding to features of the same object? The basic finding on which Crick and Koch build is that two neurons fire in synchrony when a single object, causes them to fire (Eckhorn et al. 1988; Gray et. al. 1989). This suggests that what registers the fact that a number of neurons are currently responding to features of one and the same object is that those neurons are currently firing in synchrony. There are many ways in which this line of thought can be developed. Crick and Koch argue that neurons in different regions are bound together by a mechanism that synchronizes the spikes of their firings in 40Hz oscillations; it is this synchronized firing that signals that they concern one and the same object. The Crick-Koch hypothesis is that this synchronized firing is the neural correlate of consciousness. This proposal is consistent with Treisman's cognitive model. The suggestion would be that the synchronized firing of cells in different processing streams is signalling the fact that those cells are registering the presence of various features all at the same location. Crick and Koch in fact suggest that the reason why binding is, as on Treisman's model, a phenomenon of attention, rather than being carried out automatically and in parallel for all detected features simultaneously, may be an engineering one: that the syn-

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chronized firing they describe may be a limited resource that cannot be applied to all perceived locations simultaneously. There is, indeed, a distinction between the process by which binding is carried out and the synchronized firing which signals that binding has been achieved. If Treisman's picture is correct, there must be some physiological realization of the process of singling out a location on the master map of locations, and finding which features, in the various processing streams, are at that location. At this point you might wonder whether the synchronized firing, if it exists, is not merely an epiphenomenon. Isn't the physiological basis of binding to be found in the physiological realization of the process of identifying a location on the master map and finding out which features are at that location? Whether the synchronized firing is merely an epiphenomenon depends on whether there are further physiological processes which respond to it. If synchronized firing is indeed epiphenomenal, then it is not obvious how it could be the neural basis of experience of objects; in that case, the physiological basis of the process of selecting all the features from a singled-out location would be a better candidate for being the neural correlate of experience of objects. But I set this point aside, to stay with the simple hypothesis put forward by Crick and Koch: that synchronized firing is the neural correlate of consciousness of objects. The immediate objection to this hypothesis is that the solution to the Binding Problem is a precondition of experience of the object, rather than being somehow the same as it. So the correlated firing that implements a solution to the Binding Problem may be necessary for consciousness of the object, without being itself the neural correlate of consciousness. The point I have been making, though, is that conscious attention to an object has to be able to identify that object for the benefit of informationprocessing systems. And the natural way for conscious attention to identify the object, for the benefit of the information-processing systems, is to use the parameter that was used in solving the Binding Problem for that object. In the simple Treisman model, the parameter is location. No doubt the simple Treisman model has to be made more complex, to allow for such basic possibilities as movement by the object, or some role for Gestalt grouping principles in binding together the properties of a single object. But whatever complex parameter we use in solving the Binding Problem, that will provide a kind of address for the object that is bound. And the way for conscious attention to identify the object, for the benefit of the information-processing systems, will be to use that complex parameter to identify the thing. Suppose we go back to the analogy, to the need for commensurability between the way in which you identify people and the way in which Sally identifies people. How are you to guarantee that you are using a way of

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identifying the object that Sally can use? One way would be just to operate in a hit-and-miss manner: use whatever identifiers occur to you. Some of them will be usable by Sally, and some will not. It's hard to believe that would be the right model for conscious attention. But how are you to have any guarantee that you are using the right identifiers, if you have not made a direct study of your informant—if you have not directly asked Sally which identifiers to use, or made an experimental study of your own visual system? One answer is that some hidden hand, such as evolution, has brought it about that you will be using suitable identifiers. Another, cruder way would be to use the very same physical tokens to issue requests and instructions to Sally as she uses in giving you information. So if she uses cards to give you information about a particular Reagan, just re-use those very same cards in giving her further questions or instructions. Using the same physical base twice over could give a guarantee of commensurability in the identifiers used. It would be quite a strong guarantee of commensurability. It should, I think, be testable which procedure is being used. If you are re-using the same identifiers, there is a kind of breakdown which should be impossible, one in which you simply use all the wrong codes in asking questions or issuing instructions and as a result get nowhere. If, however, there is merely a hidden hand guaranteeing that you are using suitable identifiers, it ought to be possible for the hidden hand to fail on some occasions, so that you use all the wrong identifiers and consequently get nowhere with your questions and instructions. The analogue for vision would be someone who consciously attends to the objects around him, and plans to act on those objects or to interrogate the scene for further information about them, but uses all the wrong identifiers at the level of conscious attention, so the information-processing systems cannot identify the target. It is hard to believe that this is possible, though there is always room for surprise about which pathological cases are possible; intuitively, the content of conscious attention to an object seems to be more tightly linked than that to the ways of identifying objects used in the underlying informationprocessing, so that they could not come apart. But the obvious way to secure that is to use the same physical vehicles to identify objects at the level of conscious attention as are used at the level of the underlying information-processing. Suppose you have a complex experienced visual scene before you. You consciously attend to one object, now to another. What does it come to, that you are engaging in this experiential highlighting of one rather than any other object in the scene? In effect, what I have been arguing is that it comes to this: when a particular seen object is given this experiential highlighting, when you are consciously attending to it, that affects the func-

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tional role of your experience of that object. Your experience of that object is now capable of controlling your information-processing, so that (a) you can use your information-processing capacities to verify propositions about that object, and (b) you can use your information-processing capacities to act on that object. For this to work, there must be some intrinsic aspects of your visual experience of the object, which can identify, for the benefit of subsequent information-processing, either to verify or to initiate action, which object is in question. But how exactly does your awareness of the object identify the target? What are these intrinsic aspects of the conscious experience, which identify for the information-processing system which object is in question? I am suggesting that a central aspect here is the experienced location of the object; or, more generally, the complex parameter used in binding. And in effect, what I have proposed is that we can find some support for the Crick-Koch hypothesis by asking how it is guaranteed that conscious attention is identifying the target in that way, using the complex parameter using in binding. The natural proposal is that conscious attention has as part of its neural correlate the very correlated firing that implements that solution to the Binding Problem. Of course, none of this implies that the only neural correlate of consciousness of an object would be this correlated firing. There is more to consciousness than that. You could have binding, and correlated firing implementing the binding, in the absence of consciousness. The thesis at its strongest is only that when you do have consciousness of an object—which will doubtless require the coordination of a mass of neural activity across many regions—the neural correlate of the fact that it is just that object which has been highlighted in conscious attention, is the correlated firing implementing the solution to the Binding Problem. This discussion of the neural correlate of conscious attention began from the need for there to be commensurability between the informationprocessing input that we use in verifying propositions about seen objects, and the demonstrative propositions themselves. I have been suggesting that one elegant way in which the effect could be achieved here is by the same neural circuitry serving as the vehicle of binding and as the vehicle of consciousness. But suppose for the moment we go back to the simplified introduction rule I formulated for demonstratives: FEATURE MAP: Roundness at position p That cup is round One simplification here is that location is being used as the sole binding parameter. Another point to remark is that a legitimate application of this

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rule does not require that the cup should actually be at position p, or even that the subject should believe that the cup is at position p. All that is required is that the cup should visually seem to be at position p. This is easy to see in practice. Suppose you are looking at the cup through a prism, or in a mirror. Then there is an ordinary sense in which the cup is not where it visually seems to be. But your visual system can still be using location as the binding parameter, and putting together all the information relating to that particular location in successful binding, even though the cup is not where it seems to be. And your judgements about the shape or colour of the cup, for example, can be perfectly sound even though location is being used as the binding parameter and even though the cup is riot where it seems to be. Your judgements about the shape or colour of the cup can be sound even though you do not believe that the cup is where it visually seems to be, perhaps because you suspect the presence of the prism or the mirror. There is a parallel with proper names: if the bundling principle for one collection of information circulating about an individual is 'Reagan, the actor who became President', you can use the fact that information is so tagged in forming beliefs about Reagan, even though you do not believe that he was in fact an actor; even though, say, you believe that the story of a Hollywood past is merely a romantic myth about the President. Does a similar point apply to action? I said that as a first shot, we could state the elimination rule for a perceptual demonstrative as follows: That cup contains water MOTOR SYSTEM: To reach water, move towards whatever is at position p, hand prehended thus and so But if the remarks I have just made about the introduction rule were correct, we should expect that, a parallel point would apply to the elimination rule. That is, we have to separate the role of location (a) as a binding parameter for action, allowing the putting together of all the information relevant to the action, and (b) as itself one of the parameters to be set in planning an action on an object. The point 1 have just been making is that success as a binding parameter—successful discharge of role (a)—does not require that the visual location of the object be correct, or even that the subject believe it to be correct. Presumably a similar point applies to action. But successful discharge of role (b)—setting the parameter for action—would require that the experienced location of the object be correct. At any rate, that would be so if we thought that the experienced location of the object is what we use in setting the parameters for action on the object. But as we shall see in the next chapter, that is not so. We do not, in general, use the experienced location of an object to determine how far

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away it is, in what direction, and so on. It remains true that location is a binding parameter for action, and that the experienced location of the object is what we use in identifying which thing is in question so that the motor system can swing into play appropriately when we act on the object. But let us, in the next chapter, look at these issues in more detail. We will reach a canonical statement of the introduction and elimination rules for demonstratives—a characterization of their use—in Chapter 5. What I have been proposing is that the notion of conscious attention to an object has an explanatory role to play: it has to explain how it is that we have knowledge of the reference of a demonstrative. This means that conscious attention to an object must be thought of as more primitive than thought about the object. It is a state more primitive than thought about an object, to which we can appeal in explaining how it is that we can think about the thing. As I said in the Introduction, this seems to be how Russell thought of acquaintance: acquaintance with an object is a state more primitive than prepositional thought about the object, which nonetheless explains how prepositional thought about the object is possible (Russell 1917). And by providing you with knowledge of the reference of the demonstrative, this conscious attention to the object will cause and justify the use of those introduction and elimination rules.

3 Space and Action So far I have talked about the experienced location of an object about which you are thinking demonstratively. I have said that the experienced location of the object matters because it is part of the way in which the object is identified, at the level of the subjective life. Location provides a way the object can be identified for the benefit of the neural informationprocessing systems involved in acting on the basis of propositions about that object, or verifying propositions about that thing. I have not, though, said anything about how locations themselves are identified.

1. Experience of Places How does experience of a place enable one to identify it? You might propose that place-identifiers such as 'there' identify places by their spatial relations to perceived objects. But a simple way of seeing that terms like 'there' do not work like this is to consider the possibility of illusions about the locations of perceived objects. If I am watching an object but subject to some illusion about its location—say, the desert heat is refracting the light so I am observing a scene which is actually taking place several miles away—then I may form the judgement, That palm tree is there', designating the place at which the tree seems to be. If 'there' referred merely to the place at which the palm tree is, there would be no possibility of error in that judgement of location: the term would automatically refer to the spot, several miles away, where the palm tree is. But we do have to keep open the possibility of error in the judgement: the judgement may be precisely an expression of my having been taken in by an illusion of location. There are other counterexamples to the idea that vision identifies places by their spatial relations to seen objects. In Wittgenstein's Philosophical Remarks (1975), he says that in visual space there is absolute position and absolute motion. If you watch two stars orbit one another in a pitch-dark night, you can see their movement even though their relative positions remain the same. In fact, a visual space in which there was only relative motion is not even imaginable. Suppose you were looking at a clock face

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with twelve simple bars on it, no numerals. If your visual space had only relative motion, then if you were watching a single clock hand move between two bars on a clock face, you would be able to see the movement as it left the first bar, but the moment it reached the second bar everything would be exactly as it had been initially. We can't, says Wittgenstein, visualize that. In explaining how vision can identify places, if not by their relations to seen objects, it is natural to appeal to the idea of a frame of reference used in vision. The immediate problem here is that demonstratives such as 'there', which refer to places on the basis of your current experience of them, seem to be logically simple. These demonstratives do not involve us in giving some complex identification of a place by specifying coordinates along three axes. When he asserts that visual space is not merely relative, Wittgenstein tries putting the point by saying that it is as if we could always see, as well as the usual things, a set of axes which could be used to identify the locations of the things seen. But, as he says, even that is not correct, because if you could see a set of axes, those axes would already have an orientation in the visual field—as though they were located in relation to an unseen coordinate system used to give locations in visual space (Wittgenstein 1975: 254-5). The problem is to catch the sense in which this unseen coordinate frame can be used in identifying places. The place you are referring to, when you say 'there' and point, is the place to which you are consciously attending. So the question now is how attention is directed to one place rather than another. When, in experience, you highlight one place rather than another, how is it determined which place is in question? What happens is that the attentional spotlight ranges over the places identified by the frame of reference, and the reference of 'there' depends on where the attentional spotlight is focused. If we leave it there, though, we leave it seeming that the unseen frame of reference may be altogether remote from consciousness, perhaps a subpersonal control mechanism for conscious attention which does not itself affect the nature of the conscious life. How does the fact that we are using a frame of reference in our ordinary identifications of places show up in the subjective life, if not by the axes flaring up in the visual field? One way is through the fact that we can give expression to illusions of location, as in the example of the palm tree. Another is through the fact that the space of the visual field is absolute, in Wittgenstein's sense, in that we can perceive motion even of objects whose relative positions are unchanged. We can also consider propositions about the spatial relations between perceptually demonstrated places. Suppose you attend now to one place, now to another, forming the judgement, 'This place is to the left of that

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place'. What is the epistemological status of this proposition? Is it merely a report of an empirical fact? It does not seem to be; if you understand the proposition at all then you are already in a position to know that it is true. Such a priori propositions, about the spatial relations between perceptually demonstrated places, articulate the frame of reference that we are using in our experiential identifications of places.

2. The Grounding Thesis Let's now return to the main topic, the role of conscious attention in our knowledge of the references of demonstratives referring to the objects we experience. These demonstratives can be exploited in intentional action. Suppose I see a coin on the ground in front of me. I might think,'I'll pick up that penny'. And I act on the thought. How exactly does my understanding of the demonstrative, 'that penny', contribute to my action? In particular, how does my experience of the location of the penny contribute to my action? One extreme position is epiphenomenalism. You might suggest that experience of the location of the penny is actually an epiphenomenon, so far as action goes. It plays no role in the explanation of your action. Of course, your action is spatially directed. But the spatial direction may be achieved entirely by sub-personal visuomotor systems. And, the epiphenomenalist says, there is no other role for your spatial experience to play here. To act on the thought, 'I'll pick up that penny', you do not need to formulate some proposition to the effect, 'That penny is there''. You do not need to refer demonstratively to the place where it is. Still, it might be argued that spatial experience could nonetheless be playing a role in the explanation of the spatial organization of your movements as you reach for the penny. When you act on an object, some aspects of your action are intentional and some are not. For example, when you pick up a glass, you intentionally picked up just that glass. But the exact configuration of your hand, as it moved towards the glass, would not ordinarily be intentional; it might not even occur to you that you were prehending your hand in any particular way at all. Nonetheless, the prehending of your hand might have been a causal consequence of your experience of the glass being of just the type it was. Similarly, even though you do not formulate propositions about the place of the object, still your experience of the location of the object may play a causal role in your action on the object. It may be that you are intentionally reaching for the glass just ahead and to the right. And even if you could not be described as moving in that way intentionally, it

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could still be that your experience of the location of the glass was what was causing you to move in just that way. As we shall see in the next section, it does not seem likely that this characterization of the role of experience of location in the control of action can be sustained. But it is a very natural picture. It could be set out as a way of explaining two points, which any view does have to acknowledge: (1) Demonstrative identification of objects has a special role to play in action-explanation, and

(2) Demonstrative identification of an object may depend on experience of its location. On (1), suppose there are two boxes in front of me, and my task is to choose one of them by picking it up. The right box holds enough money to remove all my financial anxieties. The wrong box holds copies of my outstanding bills. This alone means that I have already a number of ways of identifying the right box. I can think of it as 'the box containing the money', or 'the box that does not contain the bills', or simply as 'the right box'. None of these ways of identifying the box is, though, sufficient for me to be able to reach out and pick it up intentionally. What would help, and ordinarily all that would help, is a demonstrative identification of the right box. So ordinarily, when I know 'The right box is that (seen) box', then I will be in a position to say, 'So I'll pick up that box', and now I can act intentionally on the thing. For many types of object-directed action, such as reaching towards or picking up the thing, having a demonstrative identification of the object will be enough for you to be able to perform that type of action on the object. And ordinarily there will be no other way of identifying the thing that would be sufficient to allow you to perform that type of action on the thing. It is in this sense that demonstratives seem to have a special role to play in action-explanation. Thesis (2) is a traditional point from the literature on demonstratives, though its explanation is disputed. In section 5 of this chapter, we will look at G. E. Moore's discussion of the point. For the moment, here is one natural thesis, which would describe just how demonstrative reference to an object, with its experienced location, contributes to your ability to act with respect to that object: Grounding: The meaning of a perceptual demonstrative is grounded in those aspects of perceptual experience that set the parameters for my action (how far I move, in what direction, and so on). A term like 'that penny' does not have the same meaning whenever it is

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used. On any one occasion on which I use it, its meaning has to be filled out by the way in which I am perceiving the object. My current experience of the object gives me a kind of picture of the object—its shape and size, how far away it is, and so on. This picture of the object is the meaning that the term has on that occasion. And the way in which I am aware of the object— the picture of it that I consciously have—determines the coordinates of my action, it sets the details of the way in which I reach for the thing. The idea is that the perceptual information in which the meaning of a perceptual demonstrative is grounded gives a kind of descriptive meaning of the demonstrative, and this perceptual information controls the parameters of my action—how far I move, in what direction, how my hand is shaped, and so on. What explains the fact that perceptual demonstratives have this special link to action is that the meaning of the demonstrative is given by the pictorial content of the experience, which is what controls my movements. You might be encouraged in your adherence to Grounding by an uncritical reading of Alan Airport's conception of visual attention as 'selectionfor-action'. He describes it as follows: Any goal-directed action requires the specification of a unique set of (timevarying) parameters for its execution- -parameters that determine the outcome as this particular action rather than any other: as this particular vocative or manual gesture, this particular directional saccade, and so forth. Consider now what is required if these parameters are to be controlled by sensory (say, visual) information. Suppose that visual information has to guide manual reaching, for example, to grasp a stationary object or to catch a moving one. Clearly, many different objects may be present in the visual field, yet information specific to just one of these objects must uniquely determine the spatiotemporal coordinates of the end-point of the reach, the opening and closing of the hand, and so on. Information about the position, size and the like of the other objects in view, and also available, must not be allowed to interfere with (that is, produce crosstalk affecting) these parameters—though they may need to influence the trajectory of the reach in other ways. Consequently, some selective process is necessary to map just these aspects of the visual array, specific to the target object, selectively onto the control parameters of the action. (Allport 1989: 648)

To think that this amounts to an endorsement of Grounding, though, you would have to suppose that the visual information that is being used in setting the parameters for action must be part of the content of your experience of the object; and we shall see that this need not be so. To see already why there might be an alternative to Grounding, consider for a moment the example of acting intentionally on someone by ringing up that person. The analogue of 'setting the parameters of your action' here is knowing which number to ring. So you might argue that knowledge of the telephone

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number is needed to execute this type of intentional action on a person. But suppose you have a telephone which stores Sam's number. In that case, all you need to do is press the button marked 'Sam' and the machine will set the parameters for your action. You do not need to know the parameters for your action yourself. Even if you had a mistaken belief about what Sam's number was, this procedure would still let you successfully ring Sam up. If we think this a better model for the role of demonstratives in actionexplanation, the conscious experience itself need not be what sets the parameters for your action, and experience of the object will have some quite different role in explaining the action. 3. Perception vs. Action Let me sketch the case against the idea that it is experience of the location of the object that causally controls the spatial organization of your action on the thing. The epiphenomenalist will, of course, welcome this case. But we will see that you can reject epiphenomenalism while also rejecting the Grounding Thesis. It is not that experience of the location of the object has no causal role to play; it is just that it does not play the causal role envisaged by the Grounding Thesis. First, there are a number of perceptual illusions that do not affect motor responses. The spatial content of your illusory experience indicates that the action should be organized in one way; but the visuomotor system is not taken in, and the spatial aspect of the action is directed correctly. One example is the so-called Roeloff effect, where a rectangular frame contains a stationary visual target. As the frame drifts to one side, the illusion experienced is that the frame is staying still while the target is moving in the other direction. So if the spatial content of the experience were controlling the action, an attempt to point to the target would follow the apparent movement. But in fact, when asked to point rapidly to the target, subjects are accurate in their pointing. The obvious analysis of the situation is that some relatively low-level visuomotor process, remote from consciousness, is setting the parameters for your action in pointing, rather than the spatial experience itself. The same point can be made by considering experiments in which a subject is asked to point towards a target which is moved during a saccadic eyemovement (that is, the rapid jump in eye-position that ordinarily occurs several times a minute) of the subject. The subject adjusts his pointing to keep track of the object, though there is no conscious awareness of any change in the position of the target (Bridgeman, Hendryn, and Stark 1975). Similarly, subjects asked to reach for a target, which was then moved

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during a saccade, adjusted their reach to compensate for this movement, but were unaware of the change in position of the target (Goodale, Pelisson, and Prablanc 1986; Jeannerod 1997: 83). Again, it seems that the spatial content of the experience is not what is controlling the spatial organization of the movements of the subject. That is being accomplished by some relatively low-level visuomotor system. A related point is made by the so-called Ebbinghaus illusion, in which you present the subject with two target circles of the same size, one surrounded by a ring of circles smaller than it, the other surrounded by a ring of circles larger than it. The circle surrounded by a ring of smaller circles typically looks larger than the circle surrounded by a ring of larger circles. The illusion is preserved when the circles are not simply drawn on a page, but realized by thin solid discs such as poker chips. And the illusion can be manipulated so that two target circles of different sizes are made to appear the same size, by surrounding the smaller circle with a ring of smaller circles, and surrounding the larger circle with a ring of larger circles. Yet although the perceptual illusion is robust, people asked to pick up the discs set the parameters for their actions correctly: they scale their grip according to the actual size of the objects, so that the grip size is the same when the two circles are really of the same size, and different when the two circles are of different sizes (Goodale 1996; Aglioti, De Souza, and Goodale 1995). This situation is written large in the case of the patient DF studied by Goodale and Milner 1995. After carbon-monoxide-induced anoxia, DF was unable to recognize everyday objects or faces, and could not visually identify simple shapes. She could not even show how big objects were or in what orientations. So she did not seem to have experience of the spatial organization of her surroundings. She seemed to lack any basis for verbal reports of sameness or difference of shape, size, and orientation. Nonetheless, she had strikingly intact visuomotor capabilities. When she had to pick up an irregular object, she angled her fingers optimally for the grip, though she could not say which irregular objects were the same or different shapes. When she had to post a card through a slit, her movements were accurate: she oriented the card correctly and the size of her finger grip was correlated with object size. Similarly, Perenin and Rossetti 1996 looked at a blindsight patient, PJG, who was requested to post a card through a slot in the blind field, or to grasp blocks presented in the blind field. Despite the lack of awareness, the patient was accurate on those tasks: orientation of the hand posting the card was correlated with the orientation of the slot, and finger-grip size in reaching for the blocks was correlated with the size of the block. Here again, the parameters for action seem to be set by a low-level visuomotor system, remote from consciousness.

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There are many cases which show the opposite dissociation, intact spatial experience and an impaired action system. In cases of optic ataxia, patients can accurately display the size of an object by holding up their fingers to show how big it is. Or they can show the orientation of a slot they can see by holding up a card in the same orientation. So they seem to have accurate experience of the spatial layout of their surroundings. But these patients cannot accurately grasp the object, and they cannot post a card through the slot in the right orientation. Their visuomotor capacities have been impaired (Goodale 1996). Our discussion so far points to the distinction between two visual pathways, sometimes referred to as the 'action' and 'perception' pathways. This distinction is partly motivated by the anatomical distinction between dorsal and ventral visual pathways, which were originally described as 'where' and 'what' pathways. One way of setting out the distinction is provided by Jeannerod 1997, from whom I take Figure 2 (p. 54). The suggestion is that the various processing streams can be divided into (a) the computation of the direction and distance of the object, given in body-centred coordinates, for activation of reach, together with (b) size, shape and so on being computed in allocentric terms, for activation of grasp. Both of these processing streams belong to the 'action' pathway. They are contrasted with the 'perception' pathway, in which (c) properties of the object such as size, shape, colour, and so on are bound together and the object categorized by the visual system. The 'action' pathway is a relatively low-level system, remote from consciousness, used in the fine control of motor movement. Once we have this distinction in place, the natural proposal is that intentional action on a demonstrated object must involve the 'perception' pathway. For there to be a demonstrative referring to the object, there must be an involvement of high-level semantic identification of the object involved, provided by processing in the 'perceptual' pathway. 4. The Binding Thesis Does this mean that the epiphenomenalist is right, and that there is no role for the experienced location of the object in the causation of movements towards or away from the object? What I have argued so far is that the epiphenomenalist is right that there is no especial reason to suppose that spatial experience is what causally controls the spatial aspects of intentional action on an object. But that is not to say that there is no role whatever for the experienced location of the object to play in the causation of your action on the object. Suppose you identify an object on the basis of

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Fig. 2. Diagrammatic representation of central processes involved in object-orientated behaviour. Extrinsic attributes of an object (related to its spatial position) are processed in bodycentred coordinates, for activation of the reach. Its intrinsic attributes are processed in a different, parallel pathway for activation of the grasp, also pertaining to the dorsal visual pathway and to the posterior parietal areas. Shape analysis, using the same object primitives, is effected both in the dorsal pathway for visuomotor transformation and in the ventral pathway for perceptual identification. Only a few components of visual processing (for example, size cues, depth cues, etc.) are mentioned. Others are symbolized by the empty box. Semantic knowledge stored in the ventral pathway can improve visuomotor transformation using connections between the two pathways. (From Jeannerod 1994, 1997.)

your conscious experience of it, and choose to act on it: you think, 'I'll pick up that penny'. Suppose we agree with the epiphenomenalist that a lowlevel visuomotor system has to be swinging into play to set the parameters for your action in picking up the penny. There is still the problem that your visuomotor system has to be swinging into play so that you can reach the very object that you identified on the basis of experience. But how does the visuomotor system manage to connect with the right object? In terms of Jeannerod's picture, a parallel problem arises if you identify an object on the basis of semantic processing—if you think, for example, 'I'll have that penny'—and choose to act on it, there is the problem that the 'action' system has to swing into play to pick that very penny, the one that

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has been identified on the basis of semantic processing. There is a form of binding problem here, which is: how do we make sure that the 'action' and 'perception' systems are dealing with one and the same external object? I think that the natural proposal here is the one that Jeannerod makes. The picture he has in mind is that there may be early processing areas shared by the two visual pathways in which the visual primitives and spatial localization are presented on the same map (Jeannerod 1997: 80). In effect, the suggestion is that it is location that is the binding principle. Jeannerod talks about 'the classical Aristotelian notion that what arises from the same point in the external world pertains to the same object' (80). So on this view, 'attentional mechanisms would play a role in binding different modes of representation into a single, higher-order one' (80). I said earlier that conscious attention to an object is what you use in interpreting a perceptual demonstrative referring to that object. Moreover, it seems in general possible to act on objects that you have demonstratively identified. Consequently, there is the problem of explaining what the relation is between conscious attention and the capacity for intentional action on the object. The present proposal is that conscious attention to the object will include some awareness of the location of the object, and that the target for processing by the visuomotor system can be identified as 'the object at that location'. For this to be successful, the experience of location would not have to be accurate. Moreover, even if the initial experience of location was accurate, there could be subsequent changes in the location of the object which were not picked up by the 'perception' system but which were compensated for by the 'action' pathway in setting the parameters for action on the thing. The role of conscious attention to the object is not directly to set the parameters for action on the thing, but to provide enough information about the thing to define a target for the visuomotor system. Once the target is defined, it is up to the visuomotor system to set the parameters for action on the object. The epiphenomenalist rightly opposed the idea that the role of conscious experience of the object in action was to set directly the parameters for action on the object. The epiphenomenalist concludes that there is, therefore, no role for the experienced location of the object in action on the object. I am now suggesting that that is a mistake. Rather, the role of experienced location is this: conscious attention is what defines the target of processing for the visuomotor system, and thereby ensures that the object you intend to act on is the very same as the object with which the visuomotor system becomes engaged. And the way in which conscious attention identifies the target for the visuomotor system is by the experienced location of the thing. This whole procedure may work even though your experience of the location of the object is not particularly accurate. If

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you see a penny in a mirror without realizing that you are seeing it in a mirror, you may use its apparent location in verifying that it is brown, and prehending your hand correctly to pick it up, even though your experience of its location is not actually correct. There is an obvious analogy with the behaviour of a heat-seeking missile. Once the thing is launched, it sets the parameters for action on its target in its own way; but to have it reach the target you want, you have to have it roughly pointed in the right direction before it begins, so that it has actually locked on to the intended object. The role I am envisaging for conscious attention to the object, then, is to find the target of the information-processing, which need not itself be conscious, involved in acting on demonstrative propositions about the object. The reason why location matters in your experience of the object is that your conscious attention to the object has to be identifying the target for the benefit of these information-processing systems. And location is one of the ways in which the information-processing systems identity their target. Christopher Peacocke (1981) maintained that intentional action on an object requires that you have an intention to act on the object, as identified using a perceptual demonstrative. Nevertheless, the thesis, that demonstrative identification is essential for intentional action on an object, seems too strong as it stands. Telephoning someone is an intentional action that is intentional with respect to the person rung up, even though they might not be in when you ring. But ringing up Sam does not require that I currently be able to demonstrate Sam perceptually. The same point could be made about letter-writing, voting for a candidate in an election, or suing someone who has written something disagreeable about you. So you can act intentionally with respect to an object even though you cannot currently perceptually demonstrate the thing. You might point out that these counterexamples involve quite special actions on objects, rather than the reaching and grasping that Peacocke evidently had in mind. So you might say that perceptual-demonstrative intentions are essential if you are to perform a reaching or grasping action on an object. The kinds of actions in question will have to be delineated quite finely, though, for this strategy to help. You have only to think of someone with prosthetic limbs activated by spoken commands to see the possibility of someone whose reaching and grasping movements do not depend on demonstrative identification. But no doubt we can distinguish between ordinary reaching and grasping, and the reaching and grasping performed by a person with voice-activated prosthetic limbs. Even in the case of ordinary reaching for an object, though, it does not seem that the use of demonstratives is essential to action on an object. Suppose we have a blindsighted subject who has a hat present in his blind field. The subject is not in a position to identify the hat demonstratively;

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lacking any visual experience of the hat, he cannot refer to it as 'that hat'. The most the subject can do is formulate the description, 'the hat (if there is one) in my blind field'. But suppose the experimenter says, 'There is a hat somewhere in your blind field; can you reach for it?'. Since the subject now has enough descriptive identification of the object to provide a rough identification of it for his visuomotor system, he is certainly in a position to reach for the hat; given the rough descriptive guide, his visuomotor system can do the rest. The most we can say, on behalf of the thesis that demonstratives are essential for intentional action, is that usually you will not, in the absence of experience of the object, have any knowledge of where the object is, in a form that you can use to identify the thing for the benefit of your visual system. If we ask why Peacocke maintained that demonstratives are necessary for intentional action on an object, one answer is proposed by him in Sense and Content: Consider an example in which we explain your walking up to a particular man by citing your intention to shake hands with that (perceptually presented) man. The direction in which you walk varies systematically with the position your experience represents him as occupying relative to yourself. If in intention you think of a man descriptively, as when you intend to shake hands with the richest man in London, then there is no saying on the basis of your then current psychological states in which direction you would or should walk. (Peacocke 1983: 159)

Peacocke's argument here is an appeal to the idea that the parameters of your action on an object are set directly by your current experience of the object; it is, in effect, an appeal to the Grounding Thesis, and we have seen, I think, that we have to reject that idea. The parameters for your action on an object are, in general, set by a visuomotor system which may be remote from consciousness. The role for the experienced location of the object in causing your action is simply to identify, for the benefit of the visuomotor system, which object is in question. Once we have grasped that this is what is happening, there is no very obvious reason why the target of your action could not, on occasion, be identified in some other way, for the benefit of the visuomotor system. Indeed, this seems to be exactly what happens in Hindsight.

5. G. E. Moore's Commonplace Book In his Commonplace Book, G. E. Moore is vividly aware of a special connection between a visual demonstrative and the experienced location of the object. He goes so far as to propose that we can gloss the meaning of

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the demonstrative in terms of location. He says, 'Let us say "This thing" = "the thing that is here", and "that thing" = "the thing that is there'" (1962: 158). If we explain the meaning of the demonstrative in that way, then 'This thing is here' is equivalent to 'The thing that is here is here', which, as he says, is redundant, but not tautological, since it is not tautological that there is anything at all here. But. he goes on to remark a problem for the attempt to give such a gloss of the meaning of the demonstrative, in terms of a description identifying the object as the one at a particular place. If you ask, 'What's that thing there?', is the mention of a location serving to make explicit the way in which you are descriptively identifying the object? In the following passage, Moore argues that the identification of location is not serving as part of a descriptive identification of the object. This leaves him with the problem, unresolved in this passage, of explaining what the relation is between the visual demonstrative and the experienced location of the thing. What's that thing there? = (1) what's it called?, (2) what does it do, what's it for? I asked this at the Manse, and the answer was 'It's a "mixer", and is for beating up eggs, etc.'. Now this question is one which would only be asked by a person who was seeing or had recently been seeing the thing in question (a blind man might ask 'What's this thing here?', but not 'What's that thing there?', the seeing man says 'this thing here' when he's touching or nearly touching it), and he wouldn't understand the answer unless he was seeing it (the answer wouldn't be an answer to his question). Hence, 'there' for him does not merely mean, e.g. 'the nearest thing in that direction', but 'in the place where that thing is', where 'that thing' cannot = 'the thing that is there'. Can we say 'that thing' = 'the thing at which I am pointing' or 'the thing to which this finger points'? No, because the prop, in question is not understood until the thing in question is seen. 'There's a match-box there' 'That's a match-box': it answers 'Is there a matchbox anywhere about?'. The other doesn't. (Moore 1962: 158)

The proposal Moore is making in the second paragraph in this passage is that the object is not being identified by which place it is at; rather, the location in question is being identified as the location of the object. As he puts it, 'there' is being equated with 'the place where that thing is'. Consequently, we could not without circularity go on to identify which thing we were talking about by saying that it is 'there' (that is, at the place where 'that thing' is—which thing?). We have, though already seen some of the problems with this move— explaining the special connection between a visual demonstrative and the experienced location of the object by saying that the location is identified as the place at which the object is. The whole point of saying that experi-

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enced location is a frame-of-reference phenomenon is that the locations are identified prior to identifying the objects at those locations. It is only because there is this prior identification of places that we can make sense of there being visual illusions about the locations of seen objects, or movements of seen objects which do not involve objects in changing their locations with respect to one another. In effect, Moore makes a point sympathetic to this in the last paragraph of the above passage, when he remarks that 'There's a match-box there' is an answer to the question, 'Is there a match-box anywhere about?'. The use of 'there' is to locate the matchbox in the domain of search. If it were identifying the location merely as 'the place occupied by that matchbox', the use of 'there' would add nothing to the remark, 'There's a match-box', which merely asserts the existence of a matchbox without saying that it is in the search domain. Hence, this use of 'there' must be exploiting some prior way of identifying places. Moore thus ends this passage with a problem unresolved. The problem is to explain the special connection between the visual demonstrative referring to an object and the experienced location of the object. There are two proposals he considers to explain the connection. First, he suggests that 'that thing' is equivalent in meaning to the description, 'the thing that is there (at that place)'. The problems with this proposal are (a) that it cannot explain why it should be essential to an understanding of the demonstrative that you should see the object itself; after all, you could understand the description without seeing the object itself, and (b) if the place in question is identified only as the location of the object, then you cannot say which object you have in mind by saying that it is the object at 'that place'; so some alternative account of how the place is identified would be needed. The second proposal he considers is that the place is identified merely as 'where that object is'. But as we saw, this would make errors of experienced location impossible, and leave unexplained the use of 'There's a matchbox there' as significantly different to There's a matchbox'. You might say that this shows only that the relevant descriptive condition is not 'the object at position X', but 'the object which looks as if it is at position X'. The point to notice about this is that there is something metarepresentational about this use of 'looks'. We might gloss 'the object which looks as if it is at position X' as 'the object which the visual system represents as being at position X'. And to determine which object that is, it is not enough to find which object actually is at position X; the experienced location is now merely a dummy in identifying which object is being referred to. If you tell me about Bill who has committed a murder, and I ask, 'Who is Bill?', it does not begin to answer the question to say, 'He is the person who I have just told you committed a murder'. When I do begin a

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serious inquiry to identify who you were talking about, the idea of his having committed a murder may simply not be to the point: the fixing of reference may be much more fundamental than anything about the murder, it may relate entirely to his having been someone you have known for years, and so on. Nonetheless, Moore continues to insist that '"This is here" is certainly partly tautological, in some uses' (1962: 154). But if the discussion in this book has been right up to this point, that is not quite the right way to put it, because the experienced location of the object may be an illusion, so there is nothing tautological about the proposition which articulates that the object is at its experienced location. What we can say is that there is still a role for experienced location in fixing the meaning of the demonstrative, because it is the experienced location of the object that functions to control the verification of propositions about it and action on the basis of propositions about it.

4 Sortals 1. Styles of Conscious Attention Our theme is the role of conscious attention in providing knowledge of the reference of a demonstrative. Knowledge of reference, we have seen, can be viewed as causing and justifying the use of particular ways of verifying and finding the implications of propositions. So far, we have looked at the sense in which conscious attention to an object can be said to cause and justify the use of particular information-processing procedures to verify, or to act on the basis of, demonstrative propositions concerning that object. However, the things to which we can refer by means of demonstratives are of many different sorts. You can, for example, refer demonstratively to people, to valleys, and to clouds. These are different sorts of things, in the sense that there are striking differences in the ways in which their identities over time, and their boundaries at a time, are determined. In determining whether the person in the dock is identical to the person who committed the crime, for example, spatiotemporal continuity is perhaps one criterion being used; but the style of spatiotemporal continuity in question here is quite different to that relevant in finding whether this is the valley in which an infamous massacre was performed—we don't, for example, allow for the possibility of movement by valleys. And the identities of clouds have little of the complexity associated with the identities of persons. We register these differences between types of objects when we use what Locke (Essay, II. iii. 15) called a sortal concept. The idea of a sortal concept was introduced to the recent literature by P. F. Strawson in Individuals, as follows: A sortal universal supplies a principle for distinguishing and counting individual particulars which it collects. It presupposes no antecedent principle, or method, of individuating the particulars it collects. (Strawson 1959:168)

Examples of sortal concepts will include 'person', 'valley', 'cloud', and so on. The idea is that understanding such a term involves having a grasp, however provisional or inarticulate, of the criterion of identity relevant to a particular type of thing. In contrast, understanding terms such as 'red' or

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'square' does not involve any grasp of a criterion of identity; they can be applied indifferently to things of quite different sorts. As I said, I have been stressing the role of conscious attention in providing knowledge of the reference of a demonstrative. And different styles of conscious attention will be used in attending to different sorts of object. For example, if you are consciously attending to a person over a period of time, the way in which you keep track of that person will be quite different from the way in which you keep track of a valley to which you are attending over a period of time. In consciously attending to the person you will, for example, keep track of the movements of that person; but in the case of the valley you will make no such allowance for movement (certainly none for movement with respect to the flanking mountains). These differences in style of attention amount to differences in what I called the complex binding parameter used by the visual system in putting together the information true of the object. The binding parameter for a person will have to allow for the possibility of movement by the person; the binding parameter for a valley will not have to allow for any possibility of movement by the valley. As I said, the complex binding parameter in effect provides an address for the object, by which it can be identified, at the level of conscious attention, in a way that can be used in recruiting information from various processing streams to allow verification of propositions about the object, and action on the object. So the style of conscious attention to the object that is appropriate will depend on what sort of object is in question. The use of one style of conscious attention rather than another—that is, the use of one type of complex binding parameter rather than another— seems on the face of it to be a more primitive phenomenon than the ability to use sortal concepts to classify the objects to which you can attend. Animals other than humans plainly have a repertoire of binding strategies available to them: a cat keeping track of a mouse is plainly using different binding strategies than a cat keeping track of its home. It seems evident, also, that you could be using various styles of conscious attention in keeping track of various of the things around you in a new environment, for example, without yet having learned what sorts of things any of them are. Philosophers interested in the fact that we can make demonstrative reference to various quite different sorts of physical object have frequently proposed that our understanding of sortal concepts has a foundational role to play in making it possible for us to refer to objects of these various sorts. What I want to propose in this chapter, though, is that grasp of sortal concepts is a more sophisticated matter than is the mere capacity for demonstrative reference. What is important, in our capacity for demonstrative reference to different sorts of object, is our capacity to engage in different styles of conscious attention. And indeed, that capacity to engage

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in different styles of conscious attention is what plays the roles that have so often been assigned to our grasp of sortal concepts. In sections 3-5 of this chapter, I will try to define the roles that sortal concepts have been taken to play in our understanding of demonstratives. And I will argue that those roles are indeed best viewed as being taken by the more primitive phenomenon: capacities to engage in various styles of conscious attention. As a preliminary, though, I want to look first, in section 2, at the idea that our grasp of sortal concepts may underlie our capacity for various styles of conscious attention. We shall see that while this idea is engaging, it does not seem to be correct. The capacity for various styles of conscious attention is a more primitive phenomenon than grasp of sortal concepts. 2. What Justifies Binding? So far, I have talked about the binding strategies that the visual system uses to put together the various properties of a single object. The question I want to address now is: what causes and justifies our use of those strategies? Is there a role for sortal concepts in explaining how we come to use those strategies, or in explaining why those strategies are correct? To see just what question I have in mind here, and how a sortalist might answer it, it is illuminating to look first at the kinds of binding strategy used in hearing. Suppose that as you sit in a building you can hear the roar of a helicopter directly above the building; you cannot yet see the thing, though. Plainly you are in a position to use the auditory demonstrative, 'that helicopter'. There may be other sounds in the vicinity than the sound of the helicopter—people talking and so on. But your auditory system has put together the sounds produced by the helicopter. It has effectively solved the auditory analogue of the Binding Problem, for that object. How in detail the auditory system organizes sounds so that sounds produced by the same object are put together is not a topic I will address here (for discussion, see Bregman 1990). What I want to consider is a question that arises at the most general level: namely, what is the justification for the way in which the auditory system organizes the information it receives? And why does the auditory system organize sounds in the way it does? I think that in answering those questions you might suppose that there is a dependence of auditory organization on visual organization. First, when someone uses an auditory demonstrative such as 'that helicopter' to refer to a visible object, they must be able to understand an identity proposition of the form, 'That (heard) helicopter is identical to that (seen) helicopter'. You must be willing to allow that, in principle, you could be

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confronted visually with the helicopter you are hearing. Otherwise, your auditory demonstrative would not be referring to a helicopter at all, but to something quite different, namely, a sound. The organization of the auditory world is, for us, dependent on the organization of the visual world. It is because we know through vision of such things as helicopters that we can organize the auditory world as we do. You understand the auditory demonstrative 'that helicopter' only because you understand how an identity of the form, That (heard) helicopter is identical to that (seen) helicopter', could be true; there is no converse dependence of your grasp of the visual demonstrative, 'that (seen) helicopter', on the auditory demonstrative. So when your auditory system is organizing the auditory information from that helicopter into a single whole, it is using a principle of integration that depends on vision; it depends on the knowledge you have, on the basis of vision, of what such an object is. The integration that is done in hearing depends on the binding that is done in vision. Putting matters like this naturally raises a question about those who have been blind since birth. Surely such a person could still understand auditory demonstratives like 'that helicopter'. But: such a person does not have a potential to understand visual demonstratives referring to the same object. If hearing still has a dependent status for such a subject, it must be dependent on some other sense-modality, presumably touch. I do not want to attempt a serious discussion of this issue here, since it would take us very far afield. For the moment, I want to remark only that the concept formation of those born blind is obviously quite radically different to the concept formation of the sighted; and that those born blind are evidently aiming to live in a social world largely defined by the sighted, so there is evident pressure on them to conform their concepts as closely as possible to those of the sighted. The critical point for us is that the auditory demonstratives of the sighted may nonetheless depend on grasp of the connection between auditory and visual demonstratives. How is the connection made between auditory organization and visual binding? A simple, sortalist suggestion is this. You learn on the basis of vision what a helicopter is. You now grasp the sortal, 'helicopter'. In hearing, you aim to find whether there are such things as, for example, helicopters in your surroundings. So the organization of the auditory scene is driven by the objective of discerning things of the sorts with which you have been made familiar by vision. If this picture is right, then the organization of the auditory scene depends on our grasp of sortal concepts. So there is indeed a sense in which the conscious attention to the heard helicopter, which explains your grasp of the auditory demonstrative, 'that (heard) helicopter', has been focused by your grasp of such sortals as 'helicopter'.

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Even on its own terms, there are a number of ways in which this line of thought might be questioned. In particular, even if you accept that auditory integration is dependent on visual binding, you might question whether the link has to be mediated by sortal concepts. There is, after all, cross-modal binding, which seems to be a relatively low-level matter, in that it does not require the active involvement of sortal concepts. When you are looking right at something that is plainly making a noise, for example, the visual and auditory information is integrated in a way that does not depend on your conceptual thought about what is happening (cf. Ward et al. 1998 for a review discussion of cross-modal interaction). The purely auditory demonstrative may be, as it were, a limiting case of a cross-modal demonstrative, rather than being a separately motivated demonstrative dependent on visual demonstration. Whatever we say about that point in the argument, the point I want to stress for the present is that this argument at best establishes a role for sortal concepts in auditory binding to mediate the dependence of auditory binding on visual demonstratives. This line of argument does not establish a role for sortal concepts in causing or justifying the use of binding strategies in vision. Consider, for example, the use of location as a binding parameter. As I said earlier, it seems likely that the visual system uses location as a fundamental parameter in binding together different features as features of the same object: features at the same location are, as a first approximation, assigned to the same object. Someone who thinks there is a foundational place for sortal concepts in explaining how there can be conscious attention to objects may press the question: why is binding together features at the same location the right procedure for the visual system to use? What causes and justifies the use of this binding procedure? The null hypothesis is that there is nothing which justifies the use of one binding procedure rather than another. On this hypothesis, which binding procedures the visual system uses is more fundamental than either the question which objects there are in the environment, or the question which sortal concepts the subject employs. It is more fundamental than the question which objects there are in the environment, because, the argument runs, the very notion of the 'environment' is always relative to a particular type of creature; it depends on the ecological niche the creature inhabits. And, on this view, the way in which the perceptual system solves the Binding Problem is one of the things that determines what kind of world the creature inhabits. Moreover, on this view, which procedure the visual system uses to solve the Binding Problem is also more fundamental than the question which sortal concepts we use. For which sortal concepts we use depends partly on what our perceptual skills are; the most fundamental sortal concepts are observational concepts, which we can apply to

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objects on the basis of perception alone. But then the way in which our perceptual system solves the Binding Problem is one of the things which determines what kinds of sortal concepts we can have and use. So our way of solving the Binding Problem cannot be justified by reference to our use of one rather than another collection of sortal concepts. Rather, our grasp of sortal concepts simply has to work with whatever solution to the Binding Problem the visual system finds. In any area, there is always, I think, a presumption in favour of the null hypothesis; but it is a startling thought that the choice of a particular procedure to solve the Binding Problem may be quite unconstrained by anything other than the internal requirements of the visual system. We can see what the null hypothesis is saying by considering for a moment what would have to happen for the visual system to solve the Binding Problem in a radically non-standard way. Quine (1960) and Goodman (1951) used to talk about spatiotemporally scattered objects, which they claimed were just as real as anything else. So a typical spatiotemporally scattered object might comprise the top of one chair plus the base of a lightbulb. Non-standard binding would involve putting together the perceived properties of the top of the chair and the perceived properties of the base of the lightbulb as properties of a single, albeit spatiotemporally scattered, object. These features would be combined to give an 'object token', which could then be compared to stored representations to determine its characteristics. We could have a still more radically nonstandard form of binding. The properties of the top of the chair would all be bound, and the properties of the base of the lightbulb would all be bound, on the picture I just gave; the odd part is just putting the two together. But we could in principle have binding in which no two features from the same location were put together. The redness at this location, the squareness at that location, and the uprightness from a still further location could all be put together to give a single 'object token', to be compared to stored representations. The upshot would be a kind of collection of spatiotemporally scattered tropes. According to the null hypothesis, there is no justification to be given for the visual system operating in the ordinary way rather than in the ways I just described; there is no objective advantage in the standard approach. The visual system proceeds in whatever way it does; that is a primitive datum. The way in which the visual system proceeds will determine which object tokens are constructed, and that in turn will determine what stored object representations the subject has. This in turn will determine what sorts of objects are in the subject's environment; it is up to the subject to use one system of object representations rather than another to delineate which things in the surroundings he is thinking and talking about. It is

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natural to protest, as against the null hypothesis, that the way in which we actually bind objects has objective advantages over these bizarre alternatives. But the natural suspicion is that this protest is just a parochial, conservative reaction which elevates habit into a kind of transcendent superiority. What reason could be given for thinking that one way of binding features into objects is better than another? I think we can immediately say that it is not believable that there are no normative constraints on binding. There do appear occasionally individuals whose visual systems have problems with binding; see, for example, Friedman-Hill, Robertson, and Treisman 1995, or Robertson et al. 1997. These patients are quite seriously impaired. Though they may, for example, be above chance at saying which features are present in a scene displayed to them, they will be at chance when saying which combinations of features are present. Or, as in the case of the patient described by Humphreys and Riddoch (1987), they may be able to copy a drawing of a complex scene accurately, but be doing it without any identification of the objects involved. It is difficult to accept that since there are no norms of binding, these patients cannot be described as impaired. Rather, it seems that there must be normativity here, since these patients are so palpably impaired. However, you might have a view on which getting it right in your use of particular binding procedures is simply a matter of doing it the same way as everyone else. That is, you might have a view of binding which is like Chomsky's view of the innate systems he holds to be involved in language use. On this picture, there is such a thing as getting it right or wrong in your use of a particular grammar; but ultimately, rightness and wrongness here are just a question of whether you are in step with other people of the same species. Similarly, you might have, as it were, a 'community view' of binding procedures, on which rightness or wrongness is simply a matter of agreement or disagreement with others in your community. This view implies that the only problem with a non-standard binding strategy, such as putting together features at different locations, and the only problem with the impaired patients I just mentioned is social. Their only problem is that they bind differently to other people. But that seems entirely inadequate as an analysis of the problem. The problem with these subjects is that they cannot see the objects around them. The sortalist proposal, at this point, contains two elements. One is a causal hypothesis: that our visual systems use the binding strategies they do because we have the sortal concepts that we do. The other element in the sortalist proposal is normative: that what defines the objective of the binding strategies being used is the need to keep faith with the system of sortal concepts used by the subject. It has to be said, though, that neither of these ideas is compelling. Given the similarities between human vision and

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vision in other species, it seems somewhat unlikely that the use of particular binding strategies in humans evolved in response to our possession of particular sortal concepts. And it is difficult anyway to see how our possession of particular sortal concepts could have come first; our grasp of the concepts of particular sorts of observable objects depends on our abilities to perceive them, which in turn depends on having the relevant binding strategies in use already. Grasp of a system of sortal concepts thus seems to depend causally on possession of a relevant set of binding strategies, which makes it hard to see how there could also be a causal dependence in the other direction. The second element in the sortalist proposal is also difficult to accept. According to the second element, it is our system of sortal concepts that defines the objectives of the binding strategies that we use. Since the system of sortal concepts that we have presumably developed later than the binding strategies that we use, the sortal concepts are in effect providing a kind of after-the-fact justification for the use of those binding strategies, on this view. But if we have in fact developed a system of binding strategies in virtue of which we can see various sorts of objects, then we do not need the development of sortal concepts to provide a justification for the use of those strategies. The objective is simply to see the relevant objects, and binding strategies achieve that. To develop a system of sortal concepts consequently upon this achievement, and then maintain that the objectives of the binding strategies were after all being set by this system of sorta! concepts, adds nothing. We already have it in place that the objective of the binding strategies is to let us see the various sorts of objects around us, and there is no place for a further level of justification.

3. The Delineation Thesis Philosophers have, nonetheless, sometimes maintained very strong theses of sortal dependence. They have held that the ability to single out in experience a tree, or a mountain, or a lion depends on grasp of such sortal concepts as 'tree', 'mountain', or 'lion'. Their basic point is that there can be different things of different kinds in the same place at the same time. Suppose we consider a bend in the river. What object is there, at that point? There is, of course, the river, which continues on downstream. There is also a stage of a river: that is, the river as it is at this particular moment, for example. A 'river-stage' so defined cannot last longer than a moment, unlike the river. There is also a collection of water molecules at that point. This collection will have been diffused in the sea by tomorrow, unlike the

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river itself. There is also a stage of that collection of water molecules, at the same place: a momentary stage in the life of that collection of water molecules. Quine gave the basic argument here when he said: Pointing is of itself ambiguous as to the temporal spread of the indicated object. Even given that the indicated object is to be a process with considerable temporal spread, and hence a summation of momentary objects, still pointing does not tell us which summation of momentary objects is intended, beyond the fact that the momentary object at hand is to be in the desired summation. Pointing... could be interpreted either as referring to the river ... or as referring to the [collection of water molecules] . . ., or as referring to any one of an unlimited number of less natural summations... [SJuch ambiguity is commonly resolved by accompanying the pointing with such words as 'this river', thus appealing to a prior concept of a river as one distinctive type of time-consuming process. (Quine 1953a: 67)

The argument here is explicitly about pointing, which is a way of orienting attention—it is one of the control mechanisms of attention—rather than conscious attention itself. And you might argue—indeed, later in this chapter, I will argue—that Quine's argument should be read as an argument about the control of attention, rather than about what is involved in consciously singling out an object. But that is not the natural reading of the significance of Quine's comment. On the natural reading, Quine's comments imply that if you are to single out an object in experience, you have to be employing a relevant sortal concept, to delineate the boundaries of the object singled out. The idea is that that sortal concepts play, as it were, a top-down role in making it possible to pick out objects in experience. We could put the idea in terms of what I will call the Delineation Thesis: The Delineation Thesis: Conscious attention to an object has to be focused by the use of a sortal concept which delineates the boundaries of the object to which you are attending. It is, indeed, very often assumed that if you are to attend to Fs, you must already have the concept of an F (cf. e.g. Fodor 1998). But straight off, that is hard to believe. Of course, you cannot be intentionally attending to Fs without having the concept of an F; but for all that, you can be attending to an F without knowing that it is an F and without having that concept. According to Quine, the involvement of the sortal concept is needed for there to be a determinate answer to the question: 'To which object is the subject consciously attending?'. If we do not appeal to the subject's grasp of a sortal concept, how could we say what the difference is between attending to a river and attending to a collection of water molecules, for example? I think that we can answer this question by appealing to

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what I earlier called a complex binding parameter as focusing the subject's conscious attention. Since visual information-processing involves computation of the object's various characteristics in separate processing streams, the visual system has the problem of putting together all the information, in various processing streams, that relates to the same object. I have suggested that we can think of this as exploiting the location of the object together with something like the Gestalt organization of the characteristics found at that location. And, course, the visual system can bind together features over time, as when we keep track of a moving object, and across sensory modality, as when we assign heard speech to the person seen before us. This is a more primitive phenomenon, involving a more primitive level of information-processing content, than the application of sortal concepts. And I have argued that we should think of the complex binding parameter used as playing a role also in conscious attention to the object: it provides, in effect, a way of identifying the object which can be used to find information about that object in various processing streams, or to single out the object for the purpose of acting on the object. So the singling out of an object in experience need not involve the application of sortal concepts; only the mechanisms of binding. Whether you are consciously attending to a river or a mass of molecules, for example, will show up in how your visual system binds together information from the thing over time. If you have to keep moving downstream to keep track of the object of your attention, then you are attending to a collection of water molecules rather than a river. If, on the other hand, you are binding together information from any point in the course of the river, as all relating to a single object, then you are attending to the river itself. The distinction between consciously attending to a collection of water molecules, and consciously attending to a river, is not particularly hard to draw, even without appealing to any grasp of sortal concepts by the subject. It is, anyway, a fundamental point that demonstrative reference to an object can succeed even though you do not know what sort of thing you are dealing with. In a garden centre I exclaimed at the beauty of a particular plant, only to be told that it was plastic. There was no relevant ambiguity about which thing I was talking about. I had plainly referred to the plastic plant. But a plastic plant is not a plant, any more than a fake Rembrandt is a Rembrandt. You can succeed in singling out an object despite a mistaken belief about what sort of thing it is. A still more radical case is the case in which you succeed in singling out the object even though you have not the slightest idea what sort of thing it is. Suppose that by some chance, an ordinary teacup from today survives for a thousand years. And suppose that when it is discovered by our descendants, they and their circumstances have changed so dramatically that they have considerable conceptual diffi-

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culty in understanding what a teacup is. To grasp the concept they would need to have a lot of background filled in of which they know nothing as yet. But the discovered teacup prompts a lot of discussion. There are learned conferences speculating as to its nature. A strong body of opinion leans to the view that it 'probably had some religious significance'. It is kept in a glass case in a museum. Given the intense discussion it receives, it would be absurd to say that our descendants have not managed to 'single it out'. They can certainly make demonstrative reference to it; their experience of the object is sufficient to specify uniquely which thing is in question. In both these cases, the plant and the teacup, what is happening is that your visual system is managing to bind together the information from a single thing, and you are consequently able to attend consciously to it, even though you have not managed to apply the right sortal concept to it. Application of the correct sortal concept seems therefore to be a more sophisticated phenomenon than conscious attention to the object; the Delineation Thesis is simply false. The work that the Delineation Thesis allots to grasp of sortal concepts ought rather to be assigned to the principles used by the visual system in binding together the various characteristics of a single object. In particular, it is a capacity for binding, rather grasp of sortal concepts, that allows the subject to delineate the object in experience. Another way to put the point is in terms of the classical distinction between 'associative' and 'apperceptive' visual agnosias (Lissauer 1890; for discussion see Farah 2000). On the one hand, according to the classical distinction, there are 'associative' agnosias in which the patient sees the object, but does not recognize which object he is seeing—so the patient may be able to give quite a full description of the volumetric properties of, for example, a glove, but be at a loss to say what such a thing might be used for (cf. Humphreys and Riddoch 1987 on 'semantic access agnosia'). A patient of this type seems perfectly capable of using and understanding perceptual demonstratives. Such patients seem to be plain counterexamples to the Delineation Thesis; there is no question but that they have singled out the object in experience, though they are unable to give a semantic classification of it. The patient is even, in this kind of case, able to find what sort of thing it is that he is looking at. His understanding of the demonstrative means that he has the resources to understand a demonstration that the object is of this or that sort; it may be only the capacity for specifically visual recognition of the sort of the object that is impaired. What makes it so compelling that the patient is able to understand visual demonstratives is that his situation is, after all, not so very different from that of an ordinary subject given an unfamiliar view of an object of a familiar type, or a view of an object of a sort he has never seen before. In those cases, vision alone does not allow

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you to classify the object. But it is nonetheless compelling that in those cases you are still able to identify the object demonstratively, and to formulate hypotheses about that thing, or plans to act on it thus and so. Consider, in contrast, the so-called 'apperceptive' agnosics. An agnosic of this type may be able to copy complex figures, even though he insists that he has no idea what he is drawing. The patient will have no idea which objects there are to be found in the scene he has successfully copied, even though that is evident to an ordinary subject looking at the copy. Humphreys and Riddoch (1987) suggest that what is wrong here is, in effect, a problem with binding (cf. their discussion of 'integrative agnosia'). The patient is able to see the simple components of the scene and where they are; it is just that there is a difficulty with visual integration. When such an agnosic views a scene, is he in a position to understand demonstrative reference to the object before him? It seems evident that he is not. He cannot, on the basis of vision, verify propositions about the object he is seeing; he is in no position to act on the object, arid most fundamentally, his experience does not provide him with knowledge of which object is in question. It thus seems that for experience of an object to provide you with knowledge of the reference of a demonstrative referring to that object, there must be sufficient integration of the object in experience—the various features or parts of the object must provide experience of it as a coherent single thing—but this experience of the object as a coherent unity need not involve semantic classification of the object as an object of this or that sort. In Sameness and Substance, David Wiggins advances a form of the Delineation Thesis which seems designed to accommodate the possibility of singling out an object in experience even though you have made a mistake about what sort of thing it is. Wiggins says that Tor a thinker to single out or individuate a substance, there needs to be something . . . about his rapport with x or his relational state towards x and his practical sensibility in relation to x, which ... sufficiently approximates to this: the thinker's singling x out as x and as a thing of a kind f such that membership in f entails some correct answer to the question, "what is x?".' (Wiggins 2001: 7). The key point here is the idea that the subject has only to 'approximate towards' singling out the thing as a thing falling under the correct sortal concept f. So the subject can still single out the object so long as he is approximating towards correct sortal classification of it. But there are three problems with this. One is that it is not easy to see what is meant by 'approximating towards' in this context. When is one sortal misclassification a better approximation towards the right classification than another? Suppose that in the garden centre I had thought that the object was plastic, but not realized that it was a plant—perhaps I thought it was a gardening implement.

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Is that a better or worse approximation than when I thought it was a plant? There seems to be no way of answering this kind of question. The second problem is that it is simply a theorist's fiction to say that 'approximating towards the correct sortal classification' is what must be happening in the case of the teacup. It may be that as time goes on our descendants simply become less and less likely to reach a correct view about what sort of thing it is. There is nonetheless no indeterminacy as to which thing they are singling out. They are singling out the teacup. The third, most fundamental problem is this. If you are making a mistake in your classification of the object, how can that mistake be what allows you to single out the object? Surely you must be singling out the object despite your mistake, rather than because of it. How could success in a cognitive task—singling out—be constituted by a mistaken classification of an object? On the analysis I am proposing, the conscious singling out is done at a more primitive level than the one at which we have application of sortal concepts. Sortal concepts are applied to an object which you have already singled out, in consequence of your having succeeded in singling it out. And that is why singling out is consistent with incorrect, or no, sortal classification of the object. Sometimes what Wiggins says comes only to this: if you have singled out an object, then there must be a determinate answer to the question what sort of object it is. For example, he says: no substance has been singled out at all until something makes it determinate which entity has been singled out; and for this to be determinate, there must be something in the singling out that makes it determinate which principle is the principle of individuation for the entity and under what family of individuatively concordant sortal concepts it is to be subsumed. (Wiggins 2001:150-1)

This thesis has some independent plausibility; it is not, actually, a thesis about singling out, but a metaphysical thesis about the relation between existence and the possibility of sortal classification. It amounts to this: that every object can be subsumed under some type of sortal classification. If that is true, then of course singling out an object is singling out something that can be classified by a sortal. But then the point about singling out is merely a consequence of the more fundamental thesis, that everything admits of sortal classification. However, what Wiggins wants comes to more than this. Notice to begin with that in stating the metaphysical thesis, there would be no point in appealing to the notion 'approximating to'. The thesis is not that everything that exists approximates to being classified under some sortal or other. The metaphysical thesis is rather that everything that exists has some quite definite sortal classification. So the thesis about singling out comes to more than the metaphysical thesis: the idea is that singling out involves approximating towards the right sortal

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classification of the object. And Wiggins's remark was that to be singling out an object you have to be approximating towards singling it out as an object of a particular sort. On the face of it, this is a thesis about the work of the mind in singling out. It comes to more than merely the idea that each object is in fact of some definite sort. Suppose we accept the metaphysical thesis, that every object is of some definite sort. What is the argument for saying, further, that to single out an object you must approximate towards, or tend towards, singling it out as an object of some definite sort? It is not quite easy to pin down Wiggins's argument here, but here are some selective quotations which suggest a line of thought: Conceptualism [contends] that, even though horses, leaves, sun and stars are not inventions or artefacts, still, if such things as horses, leaves, sun and stars were to be singled out in experience at all ... then some scheme had to be fashioned or formed, in the back and forth process between recurrent traits in nature and would-be cognitive conceptions of these traits, that made it possible for them to be picked out. (Wiggins 2001: 150)

The role of the conceptual scheme deployed upon experience is then, on the interpretation I propose, specified in the passage which follows, and that I quoted above: there must be something in the singling out that makes it determinate which principle is the principle of individuation for the entity and under what family of individuatively concordant sortal concepts it is to be subsumed. (Wiggins 2001:151)

On this picture, the role of sortal concepts in singling out is to make it determinate which thing is being singled out. Without them, there would be no determinacy about what was being singled out. If you ask why it is not enough merely to experience a place to single out whatever it is that is at that place, the answer is: There will exist too indefinitely many items with too many distinct principles of identity and persistence which you might find in that place—the thing, the parcel of stuff that makes up the thing, and the mereological sum of all the components of that parcel, to name but three. (Wiggins 2001: 150 n. 13)

So this returns us to the argument from Quine with which I began this chapter. And exactly the same style of reply seems apt. First, it is a peculiarity of both Quine and Wiggins that they seem to find conscious attention to a particular place relatively unproblematic; there is no suggestion that attending to a place requires use of the sortal concept 'place'. Why attention to an object should not similarly be possible in the absence of a sortal concept is not explained. Moreover, it is perfectly possible to draw the distinctions Wiggins wants without appealing to sortal concepts.

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Conscious attention to the thing is manifestly quite different from conscious attention to the parcel of stuff that makes up the thing. Keeping track of the thing, even over quite a brief period of time, is manifestly different from keeping track of the parcel of stuff that makes up the thing; the difference will show up immediately the parcel of stuff is subjected to any fragmentation that does not affect the integrity of the thing, as when a small bit falls off. Someone attending to the thing will ignore the bit; someone attending to the parcel of stuff will either have to abandon the exercise or (depending on how we read 'parcel') may keep track of the totality of scattered stuff As for mereological sums, it is not obvious that they are visible at all, though their parts may be visible, so it is not obvious how you could be visually attending to such a thing. Notice also that Wiggins's argument above seems after all to demand that we have correct sortal classification of the object by the thinker. If we suppose that the mind does have to do the work of fixing the sort of the thing that is being singled out, it makes no sense to suppose that it might do the work by supplying an incorrect sortal classification. And in fact, if fixing the sort of the thing being singled out really is the task of the mind, it makes no sense to suppose that it could get it wrong; what else is there to determine what sort of thing is being singled out? If you suppose that something else—call it 'the world'—fixes the sort of the thing that is being singled out, then you can make sense of the idea that the mind could be making a mistake when it classifies the object. In that case there is no need for the mind to supply the sortal, in order to fix which sort of thing is being singled out. That task had been performed by 'the world'. But if you suppose that the world does not perform that task, then the talk of the mind doing its part by merely 'approximating towards' something or other, really makes no sense. Towards what is the mind supposed to be approximating? 4. Sortals as Orienting Attention There are two quite simple points which together can make it seem that there must be something right about the Delineation Thesis. One is that we usually do use sortal concepts in demonstrative constructions; very often, in discussion, you would not know which thing was in question unless your interlocutor used a sortal. The second point is that if someone uses an incorrect sortal classification in a demonstrative construction, then what they have said cannot be regarded as correct as it stands; once the facts are known, the statement has to be withdrawn and replaced by a use of the correct sortal classification. These points together can make it seem that

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(a) concepts are indeed essential to demonstrative reference, and (b) cases in which there seems to be singular reference but incorrect sortal classification are, after all, not cases in which the singular reference has been successful. But actually these points need to be independently explained, and they do not in the end offer any support to the Delineation Thesis. 1 will take them in turn. On the first point, there is a role for sortal concepts in demonstrative identification which is much less fundamental than the kind of role allotted to them by the Delineation Thesis, but which is commonplace and pervasive. When I commented on Quine's discussion of pointing, I remarked on the distinction between conscious attention to an object, and the control, or causation, of conscious attention. We can distinguish between the factors in virtue of which you can be said to be consciously attending to one particular object rather than anything else, and the factors which caused you to be attending to that object rather than anything else. For example, in the case of vision, it is arguable that you attend to a specific object in virtue, in part, of the fact that you are attending to the location the object is at. In contrast, I might orient your attention to the object by pointing, or by physically turning your head towards it while waggling the object in front of you. You can see the distinction between the two cases. Suppose that attending to the object is partly constituted by attending to the place, while the turning of your head is merely a cause of your attending to the object. Then you could have attended to the object, in the very same way, as a result of some other cause. For example, I could simply have pointed to the thing, or you might have become interested in it spontaneously. The upshot could still have been that you consciously attended to it in the very same way. As I said, we do not in ordinary communication confine ourselves to saying 'this' and 'that'; we very often do use phrases of the form, 'this F', where F is indeed a sortal term. Does this show that the Delineation Thesis is after all correct? I think it does not. We can distinguish between two ways in which a descriptive component can figure in demonstrative reference. Suppose you and I are strolling through the park and I point my umbrella and say something about 'that clock to the left of the fountain'. How does the descriptive component 'to the left of the fountain' relate to the demonstrative 'that clock' in this case? There are two possibilities. One is that it states a descriptive condition which has to be met by any object, if it is to be the reference of my term. So if there is no clock to the left of the fountain, I have not referred to anything. The other possibility is that the phrase, 'to the left of the fountain', is just a way of orienting your attention, exactly on a par with the flick of my umbrella, which aims to direct your attention onto an object I have already identified, prior to my use of the

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phrase or the umbrella. The identification of the object came first, and now I am trying, by hook or by crook, to direct your attention to that thing, and it does not really matter how I achieve that effect. So if the clock is not really to the left of the fountain, but I have still managed to direct your attention to it by means of my use of the phrase, then my term still refers and you understand what I have said. In these terms, we can say that one commonplace role for sortals in demonstrative identification is to orient attention to one object rather than another. The sortal really does play a role in the singling out of the object: it is what causes the orientation of attention to one thing rather than another. If I say to you, 'That is very old', you will very often have no idea which thing I am talking about until I supply the sortal, even if I point in roughly the right direction. You use the sortal to orient your attention onto the right object. But since the sortal here is functioning merely to orient your attention onto the right object, it can play its role successfully even if the object is not actually of that sort. That is why the notion of a 'plant' can be playing a role in referring to an object which is not actually a plant; it is 'good enough' in the sense that anyone looking in roughly the right direction will have their attention directed onto the right object by the sortal, even though the thing is not in fact a plant. This lets us see what was right about Wiggins' talk of 'approximating to' correct sortal classification. All we need here is that the approximation must be sufficiently close in this minimal sense: the use of the term must be successful in actually bringing it about that you attend to the right object. To say that the role of the sortal is merely to orient attention towards the right object, though, is also to say that the use of the sortal is dispensable. You could in principle have your attention oriented towards that object by some other cause. This is what happens in the case of the long-preserved teacup. Our descendants manage to orient their attention onto the thing without the use of any sortals at all. This place for the role of sortals does not give them the kind of constitutive role that the Delineation Thesis envisages in making it the case that you are consciously attending to one thing rather than another. It is merely an external causal factor in the act of conscious attention. But it does explain why typically you simply would not understand a demonstrative 'this' which was not, implicitly or explicitly, accompanied by a sortal. This point, about the role of sortals in demonstrative reference, should not be interpreted as a point about the semantic treatment of complex demonstratives in English. We can contrast simple demonstratives, such as 'this' and 'that', with complex demonstratives, such as 'this river' or 'that mountain'. Suppose that the contribution of the nominal 'F' in a phrase of

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the form 'that F' were merely to orient attention to the demonstrated object. Then the truth of a statement of the form, 'That F is G', would not require that the object referred to be F. But it does have to be acknowledged that when you use a demonstrative 'that F' to identify an object which is not in fact F, your statement cannot be regarded as correct (this was the second point we had to address). On the face of it, at any rate, if I point to a sundial and say, That clock is one hour slow', then what I say is not literally true; it implies that there is a clock which is one hour slow, and there may be no such clock. One analysis of the situation is that in addition to orienting attention, the nominal 'F' restricts what the demonstrative can refer to (cf. Kaplan 1989a, 1989b). On the view I am recommending, it would be surprising if ordinary English did work in this way. For demonstrative reference, on the view I am recommending, does not intrinsically require that you get it right about the sort of the object. But it would in principle be possible for English to impose an extrinsic requirement on reference: that when the simple demonstrative is coupled with a nominal, the nominal must apply to the object for the simple demonstrative to refer to it. It may be, though, that the nominal in a complex demonstrative contributes to the truth-conditions of a sentence containing it otherwise than by imposing a condition on the reference of the demonstrative. Strawson 1950 suggested that a sentence of the form, That F is G', says the same thing as a sentence of the form, That is the F which is G'. On this interpretation, the simple demonstrative refers without any conditions on reference being imposed by the nominal, though the nominal may indeed serve the pragmatic function of orienting attention. But the nominal does contribute to the truth-conditions of the sentence. The sentence cannot be true unless the nominal applies to the object to which the simple demonstrative refers. In a recent discussion, Lepore and Ludwig provide an analysis of the same general type, in which we have a self-standing use of a simple demonstrative and a quantificational analysis of the role of the nominal: The key to understanding demonstratives in complex demonstratives is to see the concatenation of a demonstrative with a nominal, as in That F', as itself a form of restricted quantification, namely as equivalent to '[The x: x is that and x is F]'. (Lepore and Ludwig 2000: 229)

On this analysis, the simple demonstrative refers without the nominal playing any role in fixing its reference. Such an analysis nonetheless acknowledges that a statement of the form, That F is G', cannot be true unless the object referred to is F; this is the second point with which we had to deal. And it provides no comfort to a proponent of the Delineation Thesis.

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5. Justification of a Way of Verifying Informative Identities So far I have been considering the Delineation Thesis, which assigns sortal concepts a 'top-down' role in singling out objects in experience. There is, however, another kind of role you might assign to sortal concepts—a 'bottom-up' role. Let me finally try to state what that putative role is. In considering ways in which conscious attention to an object can play a role in causing and justifying the use of particular procedures to verify propositions about the demonstrated object, I have so far concentrated on simple verification of the observable properties of the object, such as its colour or shape. There are also, though, propositions about the identity of the demonstrated object: propositions of the form, 'That F is (identical to). . .', where what fills the space occupied by the dots will be a singular term, such as another demonstrative, or a proper name, or a definite description. Some identity statements—that is, statements of the form' is identical to . . .'—are uninformative. For example, the statement that the Morning Star is identical to the Morning Star is simply an instance of the logical law that everything is identical to itself. In contrast, there are informative identity statements, such as, to use Frege's (1952) example, 'The Morning Star is identical to the Evening Star'. Such a statement cannot be verified simply by appealing to the law that everything is identical to itself. There are informative identity statements involving demonstratives. For example, I might say, 'That star is the Morning Star', pointing into the night sky. Again, establishing that proposition cannot be done simply by appeal to the laws of logic. Or if I return to my room after some time away, I might say, 'That table is the one I brought when I first came here'. Typically, establishing the truth of such an informative identity will involve the use of reasoning and inference, not just observation. Of course, there is the case in which you see the branches of a tree through one window, and other branches through another window. In this case, you might wonder, 'Is this tree (seen through one window) the same as that tree (seen through the other window)?'. And you might verify the informative identity proposition that they are identical, just by putting your head out of one of the windows. So here you might establish the identity just by observation. But often, observation alone will not establish an identity. If you want to establish that 'This man is the lost heir to the Smith millions', the reasoning through which you have to go may be quite demanding. Of course, different patterns of reasoning will be appropriate to different sorts of object. The kind of reasoning that you might use in establishing that 'this river' is identical to 'that river' will involve looking at the course of water through the local landscape, and checking the

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spatiotemporal continuity of the river-bed here with the river-bed there, and looking to see whether there are tributaries flowing into a principal river, to check that you are not identifying a tributary with the river into which it flows. This kind of reasoning is quite different from the kind of argument you would need to establish that this is the watch that was stolen from you, or again, from the kind of argument you would use to establish that this man is the heir to the Smith millions. And even if you are simply looking to see whether or not you have just one thing here, as in the case of the tree seen through the windows, or if you are simply exercising a recognitional capacity, as when you say 'That star is the Morning Star', different types of strategy will be appropriate to different sorts of objects when you are looking to see, or exercising your recognitional capacity. Grasp of these patterns of inference (or strategies of observation or recognition) is a procedural matter. It is a matter of which moves you make: which inferences you regard as valid, which procedures you use and regard as compelling. What justifies you in using such a procedure, or pattern of inference? It does not seem right to say that we can use whatever patterns of inference we like, because the correctness of a particular pattern of inference in a particular case after all depends on just which object you are dealing with. Nor does it seem right to say only that which pattern of inference to use depends only on what type of object you are in fact dealing with. To have the right to regard one rather than another pattern of inference as applicable in a particular case, we need more than simply that the object be of a suitable sort; you must in some sense have registered its relevant characteristics. At this point, it is a natural proposal that what justifies you in using one pattern of inference rather than another when verifying informative identities involving a demonstrated object is your knowledge of what sort of object is in question. This would be a 'bottom-up' use for sortal concepts. As against the Delineation Thesis, someone taking this line might accept that you can single out a particular object without your grasp of sortal concepts coming into play. Your conscious attention can be focused onto the object as a consequence, in part, of your visual system using a particular strategy to bind together information from that object. But once you have singled out the object in experience, you can go on to apply a sortal concept to it. And, you might say, it is your application of the sortal concept to the object that causes and justifies your use of a particular set of procedures to verify informative identities concerning the object. On this view, conscious attention to the object can cause and justify the use of a particular set of procedures to verify informative identities about the object only by causing and justifying your application of the right sortal concept to the object.

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On this picture, experience of the object matters only because it is instrumental in providing a sortal classification of the object, and the sortal classification amounts to an assurance that it is right to use the relevant pattern of inference in establishing informative identities using the demonstrative. You could in principle have had that information without experiencing the object. The trouble with this picture is that all that the sortal concept provides, when all the empirical work has been done and the subject's grasp of the concept made fully articulate, is at best an explicit statement of what the relevant pattern of inference is. It does not justify the use of the relevant pattern of inference, it simply says what it is. You might object that grasp of the sort of an object, when that grasp is made fully articulate and informed by all the relevant empirical discoveries, will involve spelling out just what the criterion of identity is for the object. So, for example, when you grasp that what you are referring to is a river rather than a star or a flower, spelling out the sort involves spelling out which pattern of reasoning is appropriate here. But this does not give a justification for the use of one pattern of inference rather than another; it is merely the explicit statement that one pattern of reasoning rather than another is appropriate. We might draw a comparison here with the justification of logical laws. Your grasp of the pattern of use of a classical logical constant is a procedural matter: it is a matter of which inferences you are prepared to engage in and regard as compelling. But a mere restatement of the laws themselves does not constitute a justification for your use of those laws; at best, it merely makes explicit the practice in which you are engaging anyway. We are not here being offered a justification for the use of the pattern of inference; we are simply accepting a piece of information to the effect that it is in order to use this pattern of inference, without having any understanding of why it is in order to do so. What supplies the understanding of why one pattern of inference rather than another is correct is rather, I suggest, your singling out of the object in experience. We should think of experience of objects as being what provides the justification for the patterns of inference that we ordinarily use in verifying informative identities. On this alternative picture, experience of the object is a common cause of both (a) your capacity to engage in the relevant pattern of inference, and (b) your capacity to provide a sortal classification of the object. And you might argue that experience of the object offers a common justification for (a) your use of the relevant pattern of inference, and (b) your application of the sortal concept. So we ought to be looking at the possibility that it is your experience of the demonstrated object that justifies your use of one pattern of inference rather than another in establishing identities involving that object. The capacity for sortal classification is merely an epiphenomenon. Different patterns of reasoning

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will be appropriate when establishing informative identities involving objects of different sorts. But so far, the sortal concept may play no role in justifying the use of one pattern of inference rather than another. The connection with the object that justifies the subject in using the relevant pattern of reasoning will also justify the subject in applying the relevant sortal concept. But this is a matter of there being a common cause for both (a) use of the right pattern of reasoning and (b) application of the sortal concept. This is not a picture on which the use of the sortal concept plays any role in justifying the use of a particular pattern of inference. At most, so far, you could regard the sortal concept as merely a tag indicating that one type of reasoning rather than another has to be used. In what sense does experience of, say, a dog justify the use of one type of inference rather than another to establish informative identities concerning that dog? If you have the thing in full view, you can keep track of it by keeping track of where it is, and you can put together different properties of the object as properties of the same object by using spatiotemporal continuity as your guide. Your visual system can use the spatiotemporal continuity of the object in keeping track of it. And your visual system can use the co-location of the properties you perceive in binding them together as properties of the same object. Of course there are many varieties of spatiotemporal continuity, appropriate variously to dogs, stars, and rivers. But the point is that the visual system can be using the appropriate type of spatiotemporal continuity in keeping track of the thing, whichever it is, from moment to moment, and in binding together the properties of the object as all properties of a single thing. There is no evident reason why there should be any involvement of the subject's grasp of sortal concepts in this; we are dealing with a more primitive phenomenon than sortal concepts, relating to the underlying visual system. Nonetheless, the type of procedure used by the visual system in organizing information as all relating to an individual object may provide the foundation for the patterns of reasoning we use in establishing informative identities involving the thing. The specific type of spatiotemporal continuity that is relevant is already in play in your capacity to see and keep track of the thing in the first place, so that you are in a position to understand a demonstrative referring to the object. We do have to contrast different types of experience of the thing. Suppose, for example, that late at night you are woken by the barking of a dog.' Is that dog injured?' you wonder, listening to the sound. You can certainly refer to the dog, on the basis of hearing alone, and form judgements or conjectures about it. But it does not seem that your auditory experience of the dog could be what directly causes and justifies your use of the general patterns of inference appropriate to the thing. For example, you might

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use patterns of inference which exploit spatiotemporal continuity as a criterion of identity for the thing, to establish that this dog is the one which your neighbour has just bought. But your auditory experience alone does not display the dog as a spatiotemporal continuant. As I said, it does seem to be very different in the case of a visual demonstrative, 'that dog', referring to a dog you currently have in view. Here we do seem to be directly confronted with the thing itself. And direct confrontation with the thing itself, as a spatiotemporal continuant for which particular strategies of keeping track are appropriate, does seem to be capable of providing a justification for your use of the demonstrative. This, I think, explains the dependence we remarked, in section 2 of this chapter, of the auditory demonstrative on the visual demonstrative. Of course, this distinction between ways of being presented with the object is simply invisible on a sortalist picture, on which the role of experience of the thing is merely to provide you with a sortal classification of it; for sortal classification of the object could be supplied just as well by hearing as by vision. But as I have said, we ought anyway to reject the sortalist picture. Knowledge of the reference of a demonstrative is provided by conscious attention to the relevant object. Our grasp of the identity conditions of an object over time, or the boundaries of the object at a time, is grounded not in grasp of sortal concepts, but in the style of conscious attention that we pay to the thing. And conscious attention to the object does not have to be focused by a grasp of sortal concepts; the various styles of conscious attention of which we are capable do not rely on our use of sortal concepts. Grasp of sortal concepts is a more sophisticated matter than the phenomena of reference and conscious attention.

5

Sense /. Informative Identities Frege (1952) introduces the notion of sense in terms of the informativeness of identities. The identity statement, 'The Morning Star is the Morning Star', is uninformative; the identity, 'The Morning Star is the Evening Star', is informative. The difference between the two identity statements has to be explained by a difference in the senses of the two singular terms. In these terms, the problem of the sense of a perceptual demonstrative arises because it is possible to have two demonstratives that refer to the same thing in different ways, so that the identity statement which uses the two demonstratives is informative. For example, suppose that you and I are rewiring the electrical supply to a house. We have a number of wires spilling out of a panel on the wall, and we also have a number of wires welling up from beneath the floorboards. We have to match up the wires from the wall with the wires from the floor. If I say, 'This wire [tugging at one from the wall] is the same as this wire [tugging again at that very same wire from the wall]', then 1 have simply expressed the law of identity and my statement is uninformative. If, however, I say, 'This wire [tugging at one from the wall] is the same as this wire [pointing at one from the floor]', then I have expressed an important truth; life or death may depend on it. In this case, the two demonstratives refer to the same thing. But there is evidently a difference between them. Frege calls this a difference in sense. And really that is all Frege gives us by way of a characterization of sense. Sense is that, sameness of which makes an identity uninformative, difference in which makes an identity informative. This emphasis on the notion of informativeness is unfortunate, because it has sometimes led commentators to think it telling to ask the question, 'informative to whom?' After all, you might say, if I already know that the Morning Star is the Evening Star, then it will not be informative to me to be told that the Morning Star is the Evening Star; whereas if I did not know that already, the remark will be informative. This can make it seem that Frege's criterion makes sameness or difference of sense depend on the idiosyncrasies of your prior state of knowledge. I think the right reaction

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to this comment is to put Frege's criterion directly in terms of what is, and what is not, an instance of a logical law. To be 'uninformative', in this sense, is to be an instance of a logical law. In these terms, then, the point is that 'The Morning Star is the Morning Star' is an instance of the law of identity, whereas The Morning Star is the Evening Star' is not an instance of the law of identity. And no matter what my prior state of knowledge, even if I do already know that the Morning Star is the Evening Star, the remark that the Morning Star is the Evening Star will still be a substantial piece of information, in the sense that it is not merely an instance of the law of identity. We could, indeed, put the point in terms not of which truths are logical truths, but rather, which inferences are valid inferences. In these terms, the point is that the transition, 'The Morning Star is 5 million years old; the Morning Star is a planet; hence, some planet is 5 million years old', is valid as it stands, whereas the transition, 'The Morning Star is 5 million years old; the Evening Star is a planet; hence, some planet is 5 million years old', is not valid. This second argument is enthymematic, and has to be completed by filling in the missing premise, 'The Morning Star is the Evening Star'. Similarly, consider the inference, 'This wire [tugging at the one on the wall] has been disconnected; any wire that has been disconnected is safe to touch; hence, this wire [tugging at the one on the wall] is safe to touch'. This inference is evidently valid; contrast the transition, 'This wire [tugging at the one on the wall] has been disconnected; any wire that has been disconnected is safe to touch; hence this wire [pointing at one from the floor] is safe to touch'. This second inference is not valid; anyone who thinks otherwise is in for a shock. The second inference needs to have filled in the missing premise, 'This wire [tugging at the one on the wall] is this wire [pointing to the one from the floor]'. 2. Sense and Use The points I have made so far do not exhaust the notion of sense. They do not fully bring out the connection between sense and reference, on a Classical View. It does follow from the characterization I have given so far that sense must determine reference, in that sameness of sense guarantees sameness of reference. For suppose we had sameness of sense of two terms, but not sameness of reference. Then the identity statement connecting the two terms would be uninformative, or a logical truth, because of the sameness of sense, yet false, because of the difference in reference. And that hardly seems possible. Frege goes still further than this, though, in connecting sense and reference. He says that your knowledge of the reference

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of the term is provided by your grasp of the sense of the term. And on the Classical View, knowledge of the reference of a term is what causes, and justifies, your use of particular ways of verifying, and finding the implications of, propositions involving the term. The natural question is now whether the way in which you have knowledge of the reference of the term will affect the use that you make of the term. That is, does it matter what sense you grasp the term as having, for which ways of using the term you will be caused and justified in employing? This approach applies to singular terms. Recall the descriptive name 'Elmo', for which the introduction and elimination rules were: Exactly one tree in this garden is oldest

Any tree in this garden which is oldest is F Elmo is F

and: Elmo is F exactly one tree in this garden is oldest Elmo is F any tree in this garden which is oldest is F On the Classical Model, use of these rules is caused and justified by your knowledge of the axiom: 'Elmo' refers to the oldest tree in this garden. Suppose now that there is exactly one palm tree in the garden. And suppose we have the descriptive name, 'Woody', for which the axiom is: 'Woody' refers to the palm tree in this garden. Then the rules for 'Woody' are: There is exactly one palm tree in this garden

Any palm tree in this garden is G

Woody is G

and: Woody is G There is exactly one palm tree in this garden And suppose, moreover, that:

Woody is G Any palm tree in this garden is G

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Elmo is Woody —that the palm tree is the oldest tree in the garden. Then the identity, 'Elmo is Woody', is an informative identity in Frege's sense. The identity is not merely an instance of the law of identity. And though the two terms have the same reference, they do not have the same introduction and elimination rules. The rules for 'Elmo' and for 'Woody' are, as you can see, quite different. Again, we reach the conclusion that grasp of sense is what causes, and justifies, your use of a particular pattern of use of the term—a particular set of procedures for justifying and finding the implications of propositions involving the term. At this point we can see something of the constraints on an account of the sense of a demonstrative. The most immediate remark is that it should now be apparent how incomplete it would be to regard an account of demonstrative sense as having to do only with the classification of identity statements as uninformative or informative. Rather, having characterized the introduction and elimination rules for a demonstrative—the pattern of use of the demonstrative—we can say that grasp of the sense of the term has to be what causes, and justifies, your use of just these input and output rules. It justifies your use of these rules, in the sense that it defines the objective at which you are aiming in using these procedures, and allows us to display these procedures as ways of achieving that objective. And grasp of sense has to be the cause of your use of these procedures. It is not just a coincidence that you have the objective you do, and that suitable procedures swing into play for you to achieve it. To say that it would be incomplete to regard an account of sense as a way only of classifying identity statements as uninformative or informative is not to say that we can eliminate the notion of informativeness. It is still true that we can have different ways of referring demonstratively to one and the same object, as in the example of wires with which I began. It is just that these different ways of referring to the thing will cause and justify different procedures for verification and action. But when we have one procedure and when we have two will itself have to be understood in terms of informativeness. The different procedures will themselves ultimately be individuated in terms of informativeness. I have been arguing that what provides your knowledge of the reference of a demonstrative is your conscious attention to the object demonstrated. So what we need, in an account of sense here, is a characterization of ways of consciously attending to an object that can cause and justify the use of particular input-output patterns. So different ways of consciously attending to one and the same wire can validate different verification-action

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patterns. This is exactly analogous to the point about 'Elmo' and 'Woody', that different ways of grasping one and the same reference can validate the use of quite different introduction and elimination rules. Knowledge of the reference of a demonstrative, provided by conscious attention to the object, causes and justifies the use of information-processing procedures to verify, and to find the implications for action of, propositions involving the demonstrative. So the issue of sense, as it applies to demonstratives, has to do with the relation between conscious experience and informationprocessing. What we have just found is that different ways of consciously attending to a single object can cause and justify the use of different informationprocessing procedures to verify, and to find the implications for action of, different demonstrative propositions involving reference to the same object. To characterize the sense of a demonstrative, then, we need to know how to characterize the content of conscious attention to the object, so that we can explain how one way of consciously attending to the thing can cause and justify: (1) use of one particular set of information-processing procedures to verify a proposition involving the demonstrative, and (2) use of one particular set of information-processing procedures to act on the basis of a proposition involving the demonstrative. What we have to do here, then, is to find a way of characterizing the content of your conscious attention to the object, so that we can see how the content of your conscious attention systematically causally affects which information-processing procedures swing into play in verification and in action. In Chapter 2,1 set out the relation between conscious attention to an object and the use of particular information-processing procedures to verify demonstrative propositions about the object. I described two types of verification. First, there was verification involving bringing to bear some high-level information-processing, such as the visual routines described by Ullman (1996). This is what you have to do to verify visually propositions to the effect that a particular object is enclosed by a boundary, for example. Secondly, there was verification that the object has a particular simple property, such as redness or roundness, where these properties are determined in establishing the initial feature maps used to find that there is an object there at all. In both cases, I said, it is your conscious attention to the object that causes, and justifies, the use of particular information-processing procedures to verify the proposition that the thing

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has that property. But we can ask about the details of the causation here. Just what aspect of your conscious attention to the thing is operative in determining how the information-processing swings into play? Location is a key factor from the point of view of the informationprocessing mechanisms that have to swing into play. If a visual routine is to be brought to bear on an object, the first thing that has to be found is where the object is. If a feature map is to be consulted to find which property an object has, the first thing that has to be determined is the location of the object. In Chapter 3,1 argued for a parallel picture of the relation between conscious attention to an object and the use of particular informationprocessing procedures to act on the object. I said that conscious attention to the object again causes, and justifies, the use of these informationprocessing procedures. Which actions you perform must, in general, be determined by the direction of your conscious attention, if action is to be voluntary at all. And again, we can ask which aspects of your conscious attention to the object are causally operative in determining which information-processing procedures are to swing into play. Again, as we saw, the experienced location of the object is likely to play a key role, as that can identify the target of processing for the visuomotor system. The Gestalt organization of the visual field, when you are consciously attending to the object, must also play a role, since different objects can be close together, and there must be a way in which the subject can decide to verify visually a proposition about one rather than another of those objects, and it must be possible for the subject to decide to act on one rather than another of those objects. As I stressed in Chapter 3, it is not that the experience of the object directly sets the parameters for your action on it, but rather that this can identify the target for visuomotor processing. Similarly, the experienced Gestalt organization of the target can identify the target for processing to verify a proposition about it. The experienced location of the object may not involve the very same frame of reference for identifying locations as is used in cognitive processing. Nonetheless, it is the lead candidate for systematically affecting which location is selected at the level of cognitive processing, since it will have the same structure, a structure which can sustain systematic causal connections. Similarly, it is not quite immediate that the Gestalt organization of your experience of the object is just the same as the Gestalt organization used in cognitive processing; but the Gestalt organization of your experience is, again, the lead candidate when we seek a structure in the content of experience, so there could be systematic causal connections between it and the Gestalt organization used in cognitive processing. All this suggests that we can formulate the introduction and elimination rules for a visual demonstrative somewhat as follows. Suppose we have a

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visual demonstrative, 'that wire', of whose reference you have knowledge by consciously attending to the object. The 'address' of that object will be given by the complex parameter used in binding together all the information related to that object. This parameter will typically, for a visual demonstrative, include the current location of the object, though it may involve some higher-order linkage between locations, in the case of an object of which you are keeping track as it moves over time. The parameter will also typically include the Gestalt organization of the object, though it may again involve some higher-order linkage between different styles of Gestalt organization, as the object changes over time (without changing out of recognition). Since conscious attention has to identify the object for the benefit of the information-processing system, there must be commensurability between the way in which the object is identified at the level of conscious attention and the way in which the object is identified in the information-processing subsystems. For present purposes, to give a reasonably uncomplicated exposition, I will suppose that commensurability is achieved in the simplest way, by having both conscious attention and the information-processing subsystems use the same complex parameter, p. Then we can formulate the introduction rule like this: FEATURE MAP: F-ness at p That wire is F The elimination rule will be: That wire is F MOTOR SYSTEM: To act with respect to an F wire, activate the visuomotor system to act with respect to the target identified by p. The cause, and justification, of your use of these introduction and elimination rules will be provided by the way in which you have knowledge of the reference of the demonstrative, which is supplied by your conscious attention to the object, this being focused by your experience of the object as at p.

3. Immunity to Error through Misidentification The sense of the demonstrative is given by conscious attention, focused by experienced location and Gestalt organization. At this point it may seem that what I am giving is a broadly descriptivist analysis of the meanings of demonstratives, on which the descriptive content of the demonstrative is

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provided by the binding parameter. But that would be a mistake. The demonstrative does not have a descriptive content, not even one specified by the binding parameter. But the binding parameter is constitutive of the meaning of the demonstrative. We can see exactly how the meaning of the demonstrative is related to the binding parameter by looking at how this approach deals with a broadly logical point about demonstratives: namely, that judgements about the location of a demonstrated object may be mistaken, but they are nonetheless, in Sydney Shoemaker's (1984c) phrase, immune to error through misidentification. Suppose as I stand here I hear a voice, and I look round and think, 'That woman spoke'. There are different kinds of mistake I might make. It might be that no one spoke at all, that there is simply something wrong with my ears. In that case I made a mistake, but the mistake is not one of identification; it has to do with the predicate, whether there was any speaking. In contrast, it might happen that someone spoke all right, but it was not that woman. In that case, the error is an error of identification. I was right about the speaking, but wrong about who it was. We can put it like this: the evidential basis I have for saying, 'That woman spoke', is of such a kind that I could have a ground for doubt about whether it was that woman who spoke, which did not undermine my right to claim to know, on that same evidential basis, that someone spoke. In contrast, consider a judgement about the location of a demonstrated object: suppose we have a judgement like, 'That woman is there', in which I simply identify the place the person is at. A judgement of this kind can be mistaken. For example, if there is a mirror or a prism in between us, as could happen, then I might be quite wrong about where the person is. That is not a mistake of identification; it is a mistake about the predicate I am applying to the person. For there to be an error of identification, it would have to be that I make a judgement, That woman is there', and I could be rationally brought to doubt that it is that woman who is there, but still keep my right to think, 'Well, at any rate, someone is there'. And that seems flatly impossible. (Bear in mind that I am thinking of a case in which you are identifying the person only on the basis of your current perception, not as someone you recognize or whatever.) Intuitively, you are using the perceived location of the person to single out which person you have in mind. That perception of location might be illusory. But a mistake of identification would require you to be having a veridical perception of the location of some other thing, and mistakenly attributing that location to the person you are referring to. That is what seems blankly impossible. You are not simultaneously perceiving two different people to be at the same place. So you would have to be using the veridical perceived location of one thing to visually single out something

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else, which is not at that location. And that does not seem to be a coherent possibility. So a mistake in thinking that the thing is at this particular place could not leave intact your claim to know that there is something or other at that place. The problem now is to say more explicitly just what the explanation is of this immunity to error through misidentification of judgements about the locations of demonstrated objects. There is an easy way to generate judgements which are immune to error through misidentification. Suppose we introduce a descriptive name, 'Frank', which has its reference fixed by 'the inventor of the postmark'. And suppose you have good reason to think that there was such a thing as the inventor of the postmark; it was not the product of a committee or an accidental artefact of the mailing system. Then, exploiting that background belief, and your understanding of the name, you form the judgement, 'Frank was a sole inventor of the postmark'. You are fallible about this. For there may after all have been no inventor of the postmark, despite your evidence to the contrary. But there is a kind of mistake you cannot have made. It cannot be that you are right about there having been a sole inventor of the postmark, but that you are just wrong about which person it was. It cannot be that you do know that there was a sole inventor of the postmark, but that you have made a mistake in thinking that it was Frank rather than somebody else. If you are right in thinking that there was a sole inventor of the postmark, then you cannot but be right in thinking that it was Frank who did it. To put it round the other way, if you are wrong about whether Frank invented the postmark, your mistake cannot be localized as an error of identification about who it was that invented the postmark. If you are wrong about whether Frank invented the postmark, you must also be wrong about whether there was a sole inventor of the postmark. This suggests a connection between immunity to error through misidentification, and the way in which the reference of a singular term is fixed. It suggests that the way in which it happens that there are judgements which are immune to error through misidentification, is that there are descriptive conditions on the reference of the singular term. So when the subject uses his grasp of the singular term to articulate a judgement in which the descriptive conditions are said to apply to the referent of the singular term, the result will be a judgement that cannot involve an error of identification. The point about the judgement, 'Sally spoke', is then that in an ordinary case, you are not using the fact of her speaking as a descriptive condition by which to fix the reference of 'Sally'; that is why your judgement 'Sally spoke' is subject to errors of identification. If we have a term whose reference is fixed by a descriptive condition, this will have the consequence that judgements applying that description to the

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object referred to will be immune to error through misidentification. So you might propose that we can turn this procedure around. Whenever we find judgements that are immune to error through misidentification, we can conclude that we are dealing with a term whose reference is fixed by a descriptive condition, and find what the descriptive condition is by looking at the specific contents of the judgements which are immune to error through misidentification. As we saw, judgements about the locations of demonstrated objects seem to be immune to error through misidentification. Suppose you are looking at a number of technical instruments, lying on a workbench, each of which periodically emits its own characteristic noise. When you make a judgement about the sound being made by a particular instrument, there are two kinds of mistake you could make. Suppose you think, 'That meter is humming'. One kind of mistake is that there is no humming going on at all, there is just something wrong with your ears. Another possibility is that something is humming, but that thing is not the meter. So you have made a mistake of identification: you are right about whether something is humming, but you have just made a mistake about which thing it is. In contrast, it does not seem that judgements about the locations of these instruments could be similarly subject to errors of identification. A judgement of location can involve a mistake. For example, if there is an unsuspected mirror or prism in between you and the instrument, you might see the instrument perfectly well but make a mistake about where it is. That kind of mistake is not an error of identification. To be making an error of identification, you would have to be getting it right about whether something is at that location, only that thing is something other than the instrument you are identifying. This is what seems impossible. On the approach that works for descriptive names, this would suggest that the reference of the demonstrative, 'that instrument', is fixed by some such descriptive condition as 'the instrument at this location'. But we have already run into a complication. It does not seem that the descriptive model can be quite right here. For on the descriptive model, it should be a priori that 'That instrument is at that location (if any instrument is)'; just as it is a priori that 'Frank invented the postmark (if anyone did)'. But as I already remarked, it seems entirely possible that you should make a mistake about the location of a perceived object, because of mirrors or prisms or whatever. The point is only that it will not be a mistake of identification. What, then, is the explanation of immunity to error through misidentification for the case of demonstrative judgements about the location of an object? I will argue that the phenomenon here does have to be explained by appeal to the meaning of the demonstrative. But that is not because there is any descriptive element in the meaning of the demonstrative. Rather, it

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has to do with the way in which the meaning of the demonstrative depends on the exercise of perceptual attention. On the analysis I have presented, it is your conscious attention to the object that provides your knowledge of the reference of the demonstrative. So your experience of the object has to provide enough information about it to identify the target of the information-processing involved in verifying and acting on propositions involving the demonstrative. What I have argued is that you use the experienced location of the object in identifying the target of this informationprocessing. The reason that experienced location is crucial here, I argued, is the role of location in solving the Binding Problem for the demonstrated object. Your use of a demonstrative, such as 'that person', depends on your having solved the Binding Problem. It is the fact that you are using the demonstrative 'that person' on the basis of your having bundled together all the information from location p as true of a single thing, that grounds your use of the demonstrative. It is because the solution to the Binding Problem gave a special place to location that judgements ascribing a location to the demonstrated object are immune to error through misidentification To see this, suppose we ask how it can happen that you might make an error of identification in using a demonstrative term. Suppose we stay with the case in which you make your judgement purely on the basis of vision, and that vision is using spatial location as its principle of binding. Then what has to happen for there to be an error of identification is that you do visually detect the presence of a certain attribute, so that you have the right to say, 'Something is F', even though there may be grounds for doubt as whether you are right in judging, 'That thing is F'. For you to have made such a mistake, you must have bound the attribute F-ness together, mistakenly, with a collection of attributes belonging to a different object than the object which is F. Since you are using spatial location as your principle of binding, what this means is that you have assigned F the wrong spatial location, in that it has been put together with a collection of attributes that do not belong to an object which is F. You are right in thinking that there is F-ness around, but you have mislocated it, which is how you have made your mistake of identification. But this can hardly happen with your ascription of location itself. Visual location is the principle which you are using to bind together a collection of features as features of a single object. So it does not make sense to suppose that you might have assigned the location to the wrong bundle of features. It is visual locations that individuate the bundles of features, so it does not make sense to suppose that the right location has crept into the wrong bundle. This shows a contrast between demonstratives and descriptions. An

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attention-based account on which location is the principle of selection does not regard a demonstrative like 'that person' as equivalent to a description of the form 'the person at location x'. If you descriptively identify an object by means of its location, then there is no possibility of getting it wrong about where it is; a mistake about location can only mean that you have failed to identify anything at all. You can use attention to a location to bind together the features of a single object even though it is not where it seems to be. Suppose, for example, that you see an object—say, a person— through a prism without realizing that there is a prism there. You can use the apparent location of the features to select them all, binding them together as features of a single thing, even though the object is not at that place. When you use the demonstrative, 'that person', it does refer to the object. But your judgement, 'That person is at location x', will be mistaken. Still, the judgement of location is immune to error through misidentification. You cannot have a doubt about whether the demonstrated object really is at that location, which would leave intact your evidence that, at any rate, something is at that location. There are various models for the case of demonstratives; one we considered earlier is the case of ordinary proper names. Consider the way in which testimony uses names such as 'Ronald Reagan'. Here we have an individual who is, as it were, radiating information about himself into the community, information transmitted by testimony. Suppose we ask, 'What is it, for the ordinary hearer, that bundles all this information together, as all true of a single individual?' One answer would be that on each occasion on which the name is used, the hearer must assure himself by collateral information that it is the same thing that is being talked about. But this would evidently be false to the role that proper names have for us. It is rather the sameness of the name itself that assures us that it is the same thing that is being talked about. Of course, a single name may have different uses, so on occasion, a gloss has to be supplied to indicate which Ronald Reagan is in question. So, for example, you might gloss the name with, 'the former actor who was American President in the early eighties'. This problem of organizing information disseminated by testimony into usable clusters—clusters each of which relates to just one object—is, as we saw, in some ways analogous to the Binding Problem in vision. When is a judgement involving an ordinary proper name immune to error through misidentification? Suppose, for example, that you make the judgement, 'Ronald Reagan is the former actor who was American President in the early eighties'. Could your judgement involve a mistake of identification? Mistakes of identification certainly can in principle be made using ordinary proper names. For example, you might hear a news bulletin announcing that someone has been awarded a Nobel Prize in Economics, and

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mistakenly think that it is Reagan who is being referred to. In that case, someone might provide you with grounds for doubt as to whether it was Reagan who is in question, without undermining your knowledge that someone has been awarded the Prize in Economics. Or again, at the start of the eighties, you might hear a broadcast announcing that Reagan has been elected President, and someone could challenge you at that point, accepting your evidence that a President had been elected but questioning your grounds for supposing it to be Reagan. Suppose, however, that we consider the position of an ordinarily well-informed speaker now, in the twenty-first century. Such a speaker uses some such gloss as, 'the actor who became American President in the early eighties', as his way of checking that the information he is getting concerns that Ronald Reagan; it provides his bundling principle, analogously to the use that the visual system makes of location. Suppose this speaker says, 'Reagan is the former actor who became American President in the early eighties'. This judgement is fallible. It takes a bit of an effort, but you can imagine being given strong evidence that Reagan was after all never elected President, or that he after all never was an actor. But can you envisage being given proof that though someone who was an actor was elected President in the early eighties, and though you do have knowledge of that existential proposition, still that person was not Reagan? You can imagine discovering that your whole picture of the early eighties is a complete hallucination, and that coincidentally there was a former actor who became President. But what is not conceivable is that you have knowledge that there was a former actor who became President in the early eighties, and that you are mistaken only in thinking that person was Reagan. The key point is to see that acknowledging this point does not commit you to thinking that 'Reagan' is a descriptive name, just because it is entirely possible that Reagan exists yet was neither an actor nor a President, though he was often referred to as such. The general point here is this. In the case of visual demonstratives, I have talked about binding principles, such as location. And in the case of proper names, I have talked about bundling principles, such as the gloss, 'the former actor who became President'. Such a binding or bundling principle does not deliver a definite description equivalent in meaning to the proper name. This comes out in a number of ways. Most dramatically, the binding or bundling principle is just a way of collecting together a cluster of information as all true of a single thing. For just that reason, it does not need to yield a definite description which actually is true of the object the name refers to. Nonetheless, when you articulate the judgement which ascribes the property used as your binding or bundling principle to the object referred to, the result will be a judgement which, though fallible, is immune to error through misidentification.

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4. Trading on Identity I have been arguing that we have to think of knowledge of the reference of a demonstrative as provided by conscious attention to the object in question. For conscious singling-out of the object to be what explains your knowledge of reference, it cannot itself be a matter of demonstrative reference to the thing. Otherwise, conscious attention would presuppose what it explains. If visual experience of the object was simply one way among many of having a demonstrative thought about the object, there would be no saying how visual attention to the object could be what explained your knowledge of reference. There would be no primacy for perception in the understanding of a demonstrative; your understanding of the demonstrative could not be represented as depending on your perception of the object. To understand why perception of the object may be essential to your understanding of the demonstrative, we have to take visual attention to the object to be more primitive than demonstrative identification of the thing. Nonetheless, conscious attention to the object has a certain content, as we have just seen. We experience objects as having certain locations, and it is the fact that you experience the object as having a certain location that allows you to identify the object for the benefit of the underlying systems that have to swing into play to verify or act on the basis of propositions about the thing. Moreover, it is the fact that you are using the binding parameter for the object as the way of identifying it that explains the fact that judgements about the location of the object are immune to error through misidentification, though they can be simply mistaken. Suppose we return to the problem with which this chapter began, namely, to explain why some identities are informative, or, as I suggested we reformulate the question, to explain why some inferences involving identity are valid and others are not. The example I gave earlier of a valid inference involving trading on identity was this: This wire [tugging at the one on the wall] has been disconnected; Any wire that has been disconnected is safe to touch; Hence, this wire [tugging at the one on the wall] is safe to touch. This inference is evidently valid; contrast the transition: This wire [tugging at the one on the wall] has been disconnected; Any wire that has been disconnected is safe to touch; Hence, this wire [pointing at one from the floor] is safe to touch. This second inference is not valid; it needs to have filled in the missing

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premise, 'This wire [tugging at the one on the wall] is this wire [pointing to the one from the floor]'. Some inferences involving a trading on identity are valid; some are not. In the case in which trading on identity is legitimate, your knowledge of the reference of the demonstrative should cause, and justify, your making the inferential step. So what, in general, can we say about knowledge of reference, in virtue of which it has that character? My argument has been that it is experience of the object that provides us with knowledge of reference. So can we say how it is that experience of the object causes, and justifies, trading on identity in some cases but not in others? We have seen that the way in which you experience the object can be seen as identifying the object by using the complex binding parameter by which the visual system put together the information from that object as all true of a single thing. So can we say that trading on identity is legitimate when the occurrences of the demonstrative are each being interpreted by an act of conscious attention for which the same complex binding parameter is being used? In the present context, that seems the simplest hypothesis. I think this hypothesis is basically correct, but it does need to be glossed a little. The problem emerges when we consider a case in which I am watching you manipulate, say, a matchbox. In line with the kinds of input move licensed by my grasp of the demonstrative, 'that matchbox', I might think, for example, 'that matchbox now contains my watch', having seen the watch in the thing. Unknown to me, though, you are actually manipulating two matchboxes, not one, even though it looks to me as though there is just one matchbox there. Then, as I see you filling with matches what looks like one and the same matchbox, I may think, 'That matchbox was empty a moment ago'. And I may be using the same complex binding parameter over the period. So, by our present hypotheses, I will be licensed in trading on identity to conclude that one and the same matchbox at one and the same time contained my watch and was empty. But something has gone wrong somewhere. I think that the basic point here is that there can be mistakes at the level of binding, and different degrees of error are possible. Suppose you are seated at a red traffic light, and for a split second it seems to you that the light has turned to green; but in fact this is an illusion: one of the traffic lights facing another set of traffic has turned green, and the mistake was to bind that greenness together with the rest of the perceptual information about the light facing you. In that case, it seems evident that you saw the light in front of you but just made a mistake about whether it had changed colour. (This is an error of identification.) In this case, there has been amistake at the level of binding, but not one that affects your ability to be think-

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ing demonstratively about one particular object, one particular set of traffic lights. What concerns me now, though, are more radical cases, in which the mistakes in binding mean that there is no saying which object you are perceiving. Suppose, for example, that you are rapidly presented with, in succession, a pink X and a yellow T, but perceive a pink T (Treisman and Schmidt 1982). Did you perceive the T and make a mistake about its colour, or did you perceive the X and make a mistake about its shape? It seems quite obvious that there is no answer to such a question. This is a kind of limiting case of the matchbox example. If I say, 'That figure is pink' and 'That figure is a T', and trade on identity, I will get the conclusion that one and the same thing is both pink and a T, even though there is no pink T in the display. But where did I go wrong? It is not enough, to have a way of thinking demonstratively of an object, that you be consciously attending using a particular complex binding parameter. For there to be an object you are identifying, it must be that the bulk, the overwhelming majority, of the perceptual information that you are binding together does indeed all causally derive from just one object. Otherwise, if there are, for example, two different objects in play, as in the case of the matchboxes or the pink T, there is no saying which one you are identifying demonstratively. So perhaps we could put it like this: in order for there to be a way of identifying an object in place here at all, there must be just one object from which the relevant visual information causally derives. Given that this external condition is met, we can say that trading on identity will be legitimate if the uses of the demonstrative are interpreted by an act of conscious attention in which we have the very same complex binding parameter being used. There is, though, just one further line of thought we have to add here. It is not enough that there be a single object from which most of the visual information causally derives. It must be, further, that the subject does not believe there to be a number of objects from which the relevant information derives. Suppose we go back to the case of the matchboxes one more time. But this time, suppose that what is happening is that I am watching you at work with the matchbox, and there really is only one matchbox there, so things are just as they seem. But suppose that I suspect you of trickery, and believe there to be two matchboxes in play. Then it seems evident that, by my own lights, I cannot verify propositions about 'that matchbox', and trade on identity in inferences involving the demonstrative, in the usual way. For, by my own lights, the upshot would be that I was putting together information about different matchboxes as if it all related to a single matchbox. So for the trading on identity to be legitimate, it must be

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not just that there is a single thing from which all the information causally derives, and that the information is all bound together by a single complex binding parameter. It must also be that I do not disbelieve that this is what is happening; that I do not believe that I am getting information about two different things and that my visual system is being fooled. We do not want to go so far as to demand that 1 should know that there is just one object here, as opposed to a pair of skilfully operated lookalikes; in most ordinary cases, most of us would not be able to rule out the hypothesis that there are many objects in play. Even if we believe there is only one thing in play, that is not because we can rule out a patiently constructed sceptical hypothesis on which there are two objects here being moved in some complex way that results in the illusion of a single object. But it is not, either, as though experience of the object is neutral on this point. We would ordinarily take it that our experience of the object is enough to allow us to interpret the demonstrative—to know which thing is being referred to— and, consequently, to recognize the correctness of inferences involving the demonstrative which trade on identity. This means that your ordinary experience of an object cannot be regarded as being neutral on the question whether there is one thing or two things in play. Just how we are, in consequence, to analyse the experience of the object involved in understanding the demonstrative is a matter to which I will return in Chapter 7. For the meantime, we can say that in an ordinary case, in which you experience the object—the object exists—and your visual information is causally deriving from just one thing, then you can trade on identity whenever you encounter a demonstrative which you interpret by an act of attention in which the very same complex binding parameter is used. These points, incidentally, all have their analogues in the case of proper names. Suppose we go back one last time to the name, 'Ronald Reagan'. You might think it inconceivable that an actor could ever have become President; you suspect that there are two or more different people here, the actor and the politician, for instance. In that case, you will mistakenly think that the information that is bundled together in gossip and testimony by the bundling principle, 'Reagan, the actor who became President in the early eighties', is actually a bundling together of information from at least two different individuals. So you will not be able to trade on identity in the usual way; indeed, you will not think that the name 'Reagan', as ordinarily used, serves to pick out just one rather than the other of those individuals (cf. Kripke 1979). What makes trading on identity legitimate in the ordinary case is that there is just one individual from whom derives the majority of the information bundled together by the tag, 'Reagan, the actor who became President in the early eighties'. Moreover, the ordinary speaker does not believe that there is more that one individual in play here. Whether

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a mere lack of belief here is enough, or whether something more is required, is a question I will leave open for the moment. The next three sections are somewhat subsidiary to the main line of this book; the main line resumes at the start of Chapter 6. In section 6 of this chapter, I will look at the relation of the view I am developing here to the account of demonstratives in Kaplan's 1989a and 1989b. In particular, I will look at how the role of location in demonstrative identification can be accommodated within Kaplan's framework. In section 7,1 will contrast the role that we have given to location in demonstrative identification with the role found for it in Evans 1982. Finally, at various points I have mentioned an analogy between the Classical View of knowledge of the reference of a demonstrative, and the Classical View of our understanding of the propositional constants; I will now briefly set out the analogy explicitly. 5. Propositional Constants Perhaps the simplest and most striking illustration of the Classical View is provided by the classical account of propositional logical constants, terms such as 'and', 'or', and so on. The standard way of verifying a proposition of the form 'A&B', for example, is to derive it from A together with B:

A

B

A&B The standard way of finding the implications of a proposition of the form, A&B', is to derive A from it, and to derive B from it: A&B

A&B

A

B

Suppose you ask: what causes us to use the procedures? And is there any justification for our using them? The classical answer is that the cause, and justification, for your use of these procedures is your knowledge of the classical truth-table for '&', which shows how the truth or falsity of any sentence of the form 'A&B' is determined by the truth or falsity of the constituent sentences A, B: A B A&B T T T F FT F F

T F F F

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The Classical View is that your grasp of the truth-table is what causes, and justifies, your use of the above ways of verifying, and finding the implications of, propositions of that form. Just to spell out what the truth-table says: whenever you have a complex proposition, such as 'Snow is white and grass is green', you can isolate the simpler statements from which it is built up—in this case, (a) 'Snow is white' and (b) 'Grass is green'. You can then ask what the relation is between the truth or falsity of the whole proposition, and the truth or falsity of the simple statements from which it is composed. The truth-table simply lists all the possible combinations of truth and falsity for the two simpler statements: that they are both true, that one or the other is false, and that they are both false. So there are four lines in all. Evidently, the whole statement, 'Snow is white and grass is green', is true if both constituent statements are themselves true. Otherwise—if either or both of the constituent statements are false rather than true—the whole statement is false. The truth-table simply sets this out. Whenever you have a statement of the form 'A&B', the whole thing is true if both constituents are true, and it is false otherwise. Whether ordinary speakers can in some sense be said to know truthtables for the ordinary logical constants used in everyday speech is a vexed question. (Cf, for example, Dummett 1991.) At the moment I am not aiming to force a decision on this difficult question. The point I am making is rather that the picture on which the use of a concept is caused and justified by your grasp of the concept is given an absolutely exact illustration by the view on which your use of a logical constant—the introduction and elimination rules you use for it—is caused and justified by your grasp of a truthtable for the logical constant. There is, indeed, a notorious crux over the threat of circularity at this point. How in detail is the causing and justifying of those patterns of use by your knowledge of the truth-table supposed to proceed? One easy answer is that the subject can by reflective reasoning establish that these introduction and elimination rules are the right ways to verify and find the implications of statements using a sign, '&', for which the above is the truth-table. You can establish that the rules will be truth-preserving; if the inputs are true, then, you can read off the truth-table, the outputs will be true. Moreover, the introduction rule demands as little as possible, consistently with its being truth-preserving; and the elimination rule allows you to extract as much as possible from the proposition, consistently with the elimination rule's being truth-preserving. The trouble is that the subject engaged in this kind of reflective derivation of the rules from the truthtable will have to be using deductive reasoning in the derivation. (Cf. Quine 1976.)

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The sense in which the speaker grasps the justification of the practice need not, though, involve the use of reasoning at all. The point is rather this: which particular introduction and elimination rules the speaker employs must be systematically causally dependent on which truth-table the subject associates with the sign. So the use of inference rules in connection with a logical constant is systematically dependent on which truthtable you associate with the constant. Change one line of the truth-table the subject associates with the sign, and there is a corresponding change in the inference rules the subject uses in connection with the sign. Moreover, this grasp of the truth-table acquaints you with the validation of your practice. You might point out that even on a Classical View, there is a significant contrast between prepositional constants and demonstratives, in that there is a canonical way of identifying the semantic value of a prepositional constant, but no one canonical way of identifying the semantic value of a demonstrative. The canonical way of identifying the semantic value of a prepositional constant is by way of a truth-table, such as the table for '&' given above. In contrast, the referent of a demonstrative can be identified in many different ways, and there is no single way of identifying it that has canonical status. Some such point is certainly correct. But I will not here pause over just how the point is to be spelled out—just what notion of 'canonical' we need here to explain the point, or where exactly its significance lies. For our purposes, the important fact is that there are other, non-canonical ways in which the semantic value of a classical prepositional constant can be given, and the way in which the semantic value of a prepositional constant is given will determine the correct use of the propositional constant; so that the situation here really is, to that extent, parallel with the case of names such as 'Elmo' and 'Woody' which I discussed in section 2 above. The point is that two propositional connectives could have the same semantic value even though it is not a trivial matter that they do have the same semantic value. For example, consider the connectives'+' and '#', for which the tables are as follows: A B

A+B

AB

A#B

T T

T T

T F

T if 53 is prime, F otherwise F

T if 71 is prime, F otherwise F

FT

F

FT

F

F F

F

F F

F

T F

Since 53 and 71 are both prime numbers,'+' and '#' have the same semantic

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value, and both have the same semantic value as '&'. They yield the same truth-values for the complex sentences which contain them, given the same truth-values for the constituent sentences. The two tables above provide different modes of presentation of the same semantic value. The reason it matters that these truth-functors have different modes of presentation of semantic value is that, as a result of the difference in mode of presentation, the introduction and elimination rules for the two truth-functors will be different: A

B

53 is prime

A

B

A+B

A#B

A+BA+B A

71 is prime

B

A+B 53 is prime

A#BA#B A

B

A#B 71 is prime

The difference in the modes of presentation of semantic value in the case of'+' and '#' is apparent in the fact that the two specifications of semantic value justify different sets of introduction and elimination rules. So the reason why we need the notion of a 'mode of presentation' of semantic value is to explain why it is correct to use particular sets of procedures in verifying or drawing the implications of propositions. The subject who grasps a particular mode of presentation of semantic value thereby grasps the justification for using a particular set of procedures for verifying or finding the implications of propositions. If this model is right, it confirms that we should think of grasp of sense—grasp of the mode of presentation of the semantic value of a term—as what causes our use of particular procedures to verify or find the implications of a proposition. The pattern of use you make of the term will be causally determined by the way in which you grasp its semantic value. So grasp of sense is what causes, and justifies, your use of a particular pattern of use of the term—a particular set of procedures for justifying and finding the implications of propositions involving the term.

6. Kaplan on Dthat and Demonstrations In 'Demonstratives' (1989b), David Kaplan gave an account of logical consequence for a language with demonstratives which aimed to characterize the difference between pairs of inferences such as those about the wires that I discussed above, in which trading on identity is or is not legitimate. Kaplan aimed to characterize the notion of formal validity for

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a language with demonstratives. His analysis appeals to the notion of a 'demonstration'. On this account, trading on identity is legitimate when the two demonstrative terms are associated with the same demonstration; if the associated demonstrations are different, then the trading on identity is not legitimate. But what is a demonstration? Kaplan introduces the notion as follows. He says that some indexical terms require, in order to determine their referents, an associated demonstration: typically, though not invariably, a (visual) presentation of a local object discriminated by a pointing. These indexicals are the true demonstratives, and 'that' is their paradigm. Thedemonstrative(an expression) refers to that which the demonstration demonstrates.... [TJhe referent of a demonstrative depends on an associated demonstration.' (1989b: 491-2)

The problem with this informal introduction of the notion is that it does not distinguish between a demonstration as an instrument of communication, and a demonstration as my way of achieving a visual fix on the object. There is an oscillation in Kaplan's account of demonstratives between viewing 'demonstrations'—the (in general, non-linguistic) complements of a use of a demonstrative term such as 'this' or 'that'—as instruments of communication, and viewing a demonstration as the way in which the individual thinker achieves a perceptual fix on the object. When we are thinking of demonstration as an instrument of communication, it is simply the method by which, by hook or by crook, you get your audience to attend to the right object. One method would be to grasp your hearer's head and turn it firmly towards the object, meanwhile waggling the object itself. On that kind of understanding of the role of the demonstration, it really is a ladder you climb to secure understanding, but you throw it away at the conclusion. The trouble with this is that Kaplan is quite explicit about the fact that the demonstration has a further role: it has to do with the cognitive significance of the way in which the proposition is grasped, and in particular, with how the proposition affects your propensities to action; Kaplan approvingly quotes Perry on this (Kaplan 1989b: 532). So we need some account of just how the demonstration is to impact on action. Moreover, as I said, in his formal analysis of inferences involving demonstratives, Kaplan gives an account on which trading on identity in an inference involving demonstratives is correct just in case the two demonstratives on whose identity we are trading involve the same demonstration. And in giving the account of when trading on identity is legitimate, we are considering the propositions used in the argument as grasped by a single thinker at a time, and the 'instrument of communication' notion of a demonstration is not the relevant notion. Just to illustrate this point,

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suppose you and I are watching a play and 1 notice that one of the actors seems about to faint. When I think, 'That man is about to collapse', I am visually discriminating him from his colleagues and the background. In this case, the visual discrimination, however exactly it is accomplished, is the demonstration, in that it determines the referent of the term. However, suppose I want to alert you to this situation, then my own visual discrimination is not quite what is needed to complete my use of the term, 'that man', when I say to you, 'That man is about to keel over'. If you say, 'Which one?', I have to say, 'The one second from the left on stage', The one playing King Lear', or perhaps even point. These communicative instruments succeed just when their upshot is that you visually discriminate the same man as I do. So there are two phenomena here that are covered by the notion of a 'demonstration': there is the communicative instrument, the means by which I focus your attention onto the right object, and there is the visual discrimination, the way in which I achieve my visual fix on the object. Suppose we consider a case in which you are sitting on my left, Bill is sitting on my right, and there are some actors on the stage. You whisper in my left ear, 'That actor (the one wearing a hat) is about to faint', while Bill whispers in my right ear, ' I met that actor (the one playing King Lear) once'. Can I immediately trade on identity, to conclude that, if what I have just been told is right, Bill has met someone who is about to faint? Notice first that the demonstrations associated with the two demonstratives, in the communicative sense of 'demonstration', are certainly different: you demonstrate him as 'the one wearing a hat', whereas Bill demonstrates him as 'the one playing King Lear'. However, the fact that the demonstrations are different does not of itself mean that the inference, as I understand it, cannot legitimately trade on identity. Kaplan suffers over the conflation of different notions of 'demonstration' at this point, since although he generally uses 'demonstration' in the communication-theoretic sense, he also says that the validity of the inference depends on whether we have the same demonstration here. But the demonstrations used in communication are merely instrumental to my achieving a visual fix on the person. And whether it would be legitimate for me to trade on identity depends on whether I achieved my visual fix on the object in the same way both times. This means that an account of how we understand demonstratives has to give some elucidation of the idea that there is such as thing as the way in which you achieve your visual fix on an object. Bearing in mind these problems about the interpretation of the notion of a 'demonstration', suppose we consider how the notion is to be used in giving an analysis of demonstratives. We could give the gist of Kaplan's analysis by saying that a use of a demonstrative like 'that yacht' is to be analysed by:

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dthat + [demonstration] This puts a lot of weight onto the technical term 'dthat' which Kaplan introduces. He gives a canonical explanation of the notion in 'Afterthoughts'. Kaplan writes: The word 'dthat' was intended to be a surrogate for a true demonstrative, and the description which completes it was intended to be a surrogate for the completing demonstration. On this interpretation 'dthat' is a syntactically complete singular term that requires no syntactical completion by an operand. (A 'pointing', being extralinguistic, could hardly be a part of syntax.) The description completes the character of the associated occurrence of 'dthat', but makes no contribution to content. Like a whispered aside or a gesture, the description is thought of as offthe-record (i.e., off the content record). It determines and directs attention to what is being said, but the manner in which it does so is not strictly par? of what is asserted. The semantic role of the description is pre-propositional; it induces no complex, descriptive element into content. (Kaplan 1989a: 581) Ordinarily, then, 'dthat' is to be coupled with a description, which stands in for the demonstration used in conjunction with a demonstrative. In this framework, how could we make sense of the idea that the experienced location of an object has a special connection with the meaning of the visual demonstrative referring to it? In fact, Kaplan sets out a proposal of Michael Bennett's which addresses exactly this point: Michael Bennett has proposed that only places be demonstrata and that we require an explicit or implicit common noun phrase to accompany the demonstrative, so that: that [pointing at a person] becomes: dthat [the person who is there [pointing at a place]] (Kaplan 1989b: 527-8) This proposal of Bennett's is indeed the obvious way to accommodate, within Kaplan's framework, the insight that there is a special connection between the experienced location of an object and the visual demonstrative which refers to it. The trouble is that the demonstration, in Kaplan's account, is intended to fix the reference of the demonstrative. Consequently, if the descriptive phrase, 'the person who is there [pointing at a place]', is to fix the reference of the demonstrative, 'that person', then there is no possibility of referring to a person while being under an illusion as to the location of that person. But this rules out the possibility of demonstrative identification of objects seen in mirrors, through prisms, and so on; and these certainly are real possibilities. We could rule out the possibility of error here only by supposing that the place in question is

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identified only as 'the place at which that person is located'; but then the spatial demonstration cannot fix the reference of the demonstrative. If we want, within Kaplan's framework, to accommodate the insight that there is a special connection between the experienced location of an object and the visual demonstrative which refers to it, then we have to keep Bennett's proposal but rework the explanation of 'dthat'. In effect, all that Kaplan tells us about the correct interpretation of 'dthat' in the passage quoted above is that when coupled with a demonstration which singles out an object uniquely, it yields a term whose contribution to any proposition is to identify the object on whose modal properties the modal status of the proposition depends. There is, though, more to say about the meaning of 'dthat'. We can ask how the prefixing of 'dthat' to a demonstration affects the cognitive role of propositions involving the term, and we can ask how the prefixing of 'dthat' to a demonstration affects the behaviour of propositions involving the term in inferences which trade on identity. The conclusions we reached already imply that the way to proceed here would be to: (a) keep the analysis of a demonstrative as: dthat + demonstration, but use the conception of a 'demonstration' as a way of achieving a visual fix on the object, rather than the conception of a demonstration as an instrument of communication; (b) interpret the prefixing of 'dthat' as implying that what follows is an indication of the binding principles governing your current attention to the object; this will determine the cognitive significance of the term (the way in which propositions involving it are to be verified, and the way in which to act on propositions involving the term); and (c) lay down that the validity of inferences trading on identity depends on whether the same binding principles are being used in connection with the demonstratives involved. Points (a)-(c) would, of course, be consistent with the point Kaplan was most anxious to urge in connection with 'dthat': namely, that only the object referred to, and not any of the descriptive or quasi-descriptive material involved in singling out that object, are relevant to the evaluation of the modal status of propositions involving 'dthat'. We might roughly sum up the gist of this approach by saying that, in addition to Kaplan's comments specifically on the evaluation of modal status, 'dthat' has been reinterpreted as a device signalling that what follows it is an articulation of the binding principles governing the act of attention that has been used to achieve a visual fix on the object referred to. This

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reinterpretation is needed to articulate the cognitive role of demonstrative propositions and their role in inference. An implication of this is that not just any descriptive material can follow 'dthat', because your perceptual systems cannot use just anything to bind information as all relating to a single object. The special role that location has, as perhaps the single most pervasive binding principle, will then be reflected in Bennett's proposal that only identifications of objects by way of location can follow the use of 'dthat'. But we need not go as far as Bennett in the insistence that only location will do; we could allow that on occasion you may be able to identify an object perceptually without perceiving its location, and that in those cases the demonstrative you use will not depend on a demonstration identifying location. 7. Evans on Demonstratives I want finally to contrast the account I have given with Evans's (1982) remarks on demonstratives. Evans gives an important place to location in the meaning of a visual demonstratives. But he has a quite different explanation to the analysis I have been giving of why it is important. The contrast begins with the generality of his account. The varieties of reference he discusses are all in fact identifications of physical things. But he is trying to fit them to a mould designed equally for all types of singular reference, including reference to abstract objects. He says that 'in the case of a proposition of the form "a is F", knowledge of what it is for it to be true must be the result of two pieces of knowledge, one of which can be equated with an Idea of an object, and the other with an Idea of a property, or, more familiarly, a concept' (Evans 1982: 106). This point is the core of his conception of singular reference. Grasp of a singular way of thinking is to be explained, on this view, as requiring a capacity to think a certain range of thoughts. In effect, a 'functional' characterization is given. To grasp a singular idea a, one must be capable of grasping such thoughts as that a is F, that a is G, and so on, for each way of thinking of a property available to one. The task of a theory of singular reference is to explain what makes this possible. Evans's answer is that what makes this possible is that one's grasp of the idea a consists in what he calls discriminating knowledge of which thing a is. Evans's conception of discriminating knowledge is explained and defended by reference to his distinction between fundamental and nonfundamental singular ideas. This distinction is applicable equally to singular ideas of all types: to ideas of abstract as to ideas of concrete objects. A fundamental idea of an object identifies it as an object of a certain sort: as,

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for example, a number, or a shape, or a mountain. It further identifies it as the possessor of the characteristics which ultimately differentiate it from all other things of the same sort. Thus a number is ultimately differentiated from all other numbers by its position in the number series; this is called the 'fundamental ground of difference' of the object. The fundamental ground of difference of a spatial object is taken to be its location at a time: its position then with respect to other objects. The most basic way in which one can have discriminating knowledge of an object is, on Evans's account, by grasping a fundamental idea of it; that is, by knowing what sort of thing it is, and those of its characteristics which ultimately differentiate it from all other things of that sort. As he says, 'Such an Idea constitutes, by definition, distinguishing knowledge of an object, since the object is differentiated from all others by this fact'; that is, the fact of its having the particular fundamental ground of difference that it does (1982:107). Yet why should we think that distinguishing knowledge in this sense is sufficient for singular reference? At this point Evans appeals to his doctrine about the way in which first-level concepts are understood. The doctrine is that in the first instance, possessing a concept of the property of being F is knowing what it is for a proposition of the form '6 is F' to be true, where '<5' is, precisely, a fundamental idea of an object. It is, on this view, by reference to the level of fundamental ideas that predicative concepts are first introduced and explained. That is why grasp of a fundamental idea '<5' must be sufficient to enable one to grasp such thoughts as '<5 is F', '6 is G', and so on, for each way of thinking of a property available to one, so that one conforms to the 'functional' characterization of singular reference. And as we have seen, singular reference is, on Evans's view, just whatever fills this role. This raises the question how there can be such a thing as nonfundamental singular reference. For if predicative concepts are explained at the fundamental level, how could one's grasp of a predicative concept F and one's grasp of a non-fundamental idea a combine to yield one's apprehension of the thought that a is F? Evans's answer is that the discriminating knowledge-constituting grasp of a non-fundamental idea a is knowledge of what would make true an identity of the form 'a is identical to 6' , where '<5' is an arbitrary fundamental idea. It is because of this constitutive tie to the fundamental level that there is such a thing as nonfundamental singular reference. Evans sums up the position as follows: When our Idea of an object is -Afundamental Idea, the knowledge which constitutes our possession of the concept of being F can apply directly, to yield a knowledge of what it is for the proposition '<5* is F' to be true. When our Idea of an object is of a non-fundamental kind, we know what it is for a proposition of the form 'a is F' to be true, because we know that it is true (if it is) in virtue of the truth of some pair of propositions of the forms 'd — a' and '6 is F'; and our Idea of the object and our

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concept of the property constitute, respectively, knowledge of what it is for propositions of these forms to be true. Provided a subject knows what it is for identifications like '<5 = a' to be true, a link is set up between his Idea, a, and his entire repertoire of conceptual knowledge, and he will be able to grasp as many propositions of the form 'a is F' as he has concepts of being F. His Ideas make contact with his concepts, so to speak, at the fundamental level. (Evans 1982:111-12)

How does this account apply to demonstratives? According to Evans, a visual demonstrative is what he calls an 'information-based' term. This means that there are two components to its ordinary functioning. On the one hand, there is the causal source of the information that one has about the thing. And on the other hand, there is the content of the information that the causal links supply, in virtue of which the thinker knows which thing he is talking about. It is this information that provides the thinker with the basis for his knowledge of what it would be for an arbitrary statement of the form, 'That instrument is <5', to be true. Here what replaces '<5' will be an identification of the subject as a spatiotemporal thing, identified at some 'objective' level of spatiotemporal thought. The proper use of the demonstrative 'that instrument' requires that the causal source of the information should be the same thing as the thing which best matches the content of the information supplied by the link (Evans 1982:139). The idea, then, is that there must be some 'match' between the content of the information delivered by the causal link, and the thing with which there is the causal linkage. The information delivered by the causal link is held to be uniquely individuating; in Evans's terms, it must enable the user of the term to 'discriminate the thing referred to from all other things'. And it has to do so by providing the subject with the capacity to identify its spatiotemporal location. That is why location matters. I can make vivid Evans's picture of the way in which perceptual demonstratives work by explaining the idea of a new type of demonstrative, one which we do not actually have, as things stand. So that we have an example to work from, suppose that tomato A is directly behind a mirror set at 45 degrees to the subject's line of vision, so that tomato A is at the position at which tomato B, reflected in the mirror, appears to the subject to be. Though the subject can see tomato B in the mirror, the presence of the mirror is not suspected by her. Now an ordinary perceptual demonstrative, 'that tomato', used by the subject in this case, would refer to the tomato seen in the mirror. There is no prospect of the subject using an ordinary perceptual demonstrative to refer to the tomato hidden behind the mirror. The ordinary use of the demonstrative does require a causal-perceptual link, and the subject does not have that kind of causal-perceptual link to the tomato behind the mirror. But could we not introduce a range of perceptual demonstratives of a second type? These perceptual demonstratives

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would not rely upon a causal-perceptual link. Rather, they would use perceptual information to give a descriptive identification of the object. So such a demonstrative, 'yonder object', would identify its referent as the tomato at such-and-such a location—as 'the tomato there'—where the location is identified using the primitive frame of reference involved in vision. Here the object has been identified by its type and location, without relying on a causal-perceptual link between it and the subject. Using this kind of demonstrative, it would be possible for our subject to make reference to tomato A, the tomato hidden by the unsuspected mirror. This kind of perceptual demonstrative, using perceptual information to give in effect a kind of descriptive identification of the object, seems perfectly well defined, though, as I said, we do not actually have such demonstratives. In using a demonstrative of this second type, it would be impossible to make a mistake of identification in articulating a judgement of location. Suppose we now introduce a further type of demonstrative. For a demonstrative of our new type to refer to an object, the object must be at the place where there seems to be an object of the relevant sort (so in this respect it is just like a demonstrative of the second type). But there is a further condition on reference: for the demonstrative to refer to an object there must also be a causal-perceptual link between that object and the use of the demonstrative. So we have two separate conditions on successful reference, descriptive and causal, which must both be met for the demonstrative to refer. On Evans's account, this is how we actually use perceptual demonstratives (Evans 1982: 132-5). The problem with this is that it assimilates demonstratives to descriptive names, in the following sense: it implies that if you make a mistake about the location of the object, you are not in a position to refer to the object at all. So you cannot refer demonstratively to an object which you see through a prism that you do not know is there. This view has no plausibility at all. It implies that you cannot even think demonstratively about an object you can see perfectly well, because you are subject to some illusion about its location. A further difficulty is that this account rejects the possibility of auditory demonstratives which may refer to ordinary physical objects without you having any perception of their locations. If I hear an ear-shattering drill at work somewhere outside my room, I may have no perception or knowledge of where it is. Nonetheless, it is a datum that I can refer to the drill by means of a demonstrative, and make complaints like, 'That drill is noisy'. On Evans's account, the lack of perception of location means that I cannot refer, on the strength of my hearing it, to 'that drill'. On his account, I do not, in my understanding of the demonstrative, have the resources to let me understand a proposition of the form, 'That drill is identical to 6' . So I can-

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not understand any proposition of the form, That drill is F'. For on this account, any predicate F is first introduced and explained at that fundamental level of thought. An understanding of the demonstrative, on this view, requires that I perceive the location of the drill. To abandon any component here would mean that Evans lost his analysis of the role of location in the understanding of a visual demonstrative. But the whole picture is not credible. Predicates such as 'noisy' are obviously first introduced and explained at the level of demonstrative propositions themselves, used in connection with perceived objects. As we saw in Chapter 4, it is arguable that an auditory demonstrative such as 'that drill' is dependent on there being other ways of referring to the thing; an understanding of that auditory demonstrative does mean that you can comprehend the possibility of a more direct, perhaps visual confrontation with the thing itself. But this has to do with the relations among different types of demonstrative; not a relation between demonstratives and some hypothesized non-demonstrative type of singular identification. The background problem is Evans's explanation of why location matters for visual demonstratives, and in particular his conception of the 'fundamental level of thought'. It seems evident that we cannot sustain this conception of a level of thought, more fundamental than the level of perceptual demonstratives, at which predicates of physical things are first introduced and explained. In the case of physical objects, we have to acknowledge that predicates such as 'flashing' must be first introduced and explained at the level of perceptual demonstratives, in the context of judgements such as, 'That light is flashing'. The idea that observational predicates have to be first introduced in the context of some other level of thought than demonstrative thought, so that the importance of location can be explained in terms of its link to that level, cannot be sustained. The reason why location matters for the meaning of a visual demonstrative has to be explained rather in terms of the special role of location in attention and binding.

6 The Relational View of Experience 1. The Explanatory Role of Experience I have been arguing that experience of objects has an explanatory role to play: it explains our ability to think demonstratively about perceived objects. Experience of a perceived object is what provides you with knowledge of the reference of a demonstrative referring to it. In this chapter I want to look at the way in which we should characterize the phenomenal content of experience; that is, how we should give the most direct and explicit characterization of the qualitative nature of particular experiential states. I do not think we can expect there to be one uniform style of characterization that applies equally to all conscious states: to seeing a rainbow and to feeling anxious, to having a word on the tip of your tongue and to remembering an autumn afternoon from years ago. In this chapter, I want to focus on the characterization of our perceptual experience of objects. What is important about this case is that we have a way of telling when the characterization is correct. Whatever else is true of it, experience of objects has to explain our ability to think about those very objects. So a characterization of the phenomenal content of experience of objects has to show how it is that experience, so described, can be what makes it possible for us to think about those objects demonstratively. Suppose, for example, you hold that experience of objects is a matter merely of having sensations, and that a characterization of the phenomenal content of experience is exhausted by a characterization of sensation. Then you leave it opaque how it is that experience of objects could make it possible to think about them. At best, the subject possessed of such sensations could formulate descriptions such as 'whatever is causing this sensation'. It is, on this view, opaque how experience of an object could constitute the kind of simple acquaintance with the object that provides knowledge of the reference of a simple demonstrative. In this chapter, I will argue that if we are to acknowledge the explanatory role of experience of objects, we have to appeal to what I will call a Relational View of experience. On a Relational View, the qualitative character of the experience is constituted by the qualitative character of the

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scene perceived. I will argue that only this view, on which experience of an object is a simple relation holding between perceiver and object, can characterize the kind of acquaintance with objects that provides knowledge of reference. Of course, we have so far not begun to survey the various views you might hold here. In particular, I have not mentioned views on which the content of perception is one or another kind of representational state. But I postpone considering such views for a moment, in order to look once again at the basic point: that experience of objects has a role to play in explaining our knowledge of reference. Suppose that you live in one of a terraced row of houses, and you sometimes hear noises from the house next door. Being of an enquiring turn of mind, you formulate hypotheses about what objects are to be found next door. There's a couple, you conjecture, a man and a woman, though you never see them directly—there are two cars outside, you occasionally hear noises coming simultaneously from different parts of the house next door, and sometimes there are raised voices. You conjecture that there's a model railway next door—that's the only hypothesis you can think of to explain some of what you hear. And so on. Not all the objects you posit are postulated as noise-producers: for example, you might postulate a mirror at a certain place, in explaining the occasional sound of an electric razor. If you are of a formal turn of mind, you might write down your hypotheses. You could say: There are objects xt, x 2 ,..., xn, which stand to one another in the following relations. . ., and which stand in the following relations to the audible phenomena . . . You could, in effect, give a functional characterization of all the particular objects you postulate as being next door. And you might test and confirm your hypotheses over a long period, without ever catching sight of those things. Suppose now that the day finally arrives when you do get a look inside the house. What does this add to your knowledge? Perhaps the hypotheses you formed had been amply confirmed long before your look inside, so the existence of objects with these particular functional roles does not get significant further confirmation from your observation. Nor is it that you can now refer to those particular objects but could not refer to them before. You could have referred to those particulars before. The functional roles you postulated were, so to speak, token functional roles postulated ultimately in the explanation of particular auditory phenomena. So you already had the conceptual materials to identify uniquely each of the relevant objects. The contrast between the knowledge you have now, on the basis of a look at the objects, and the knowledge you had before of the existence of objects with particular functional roles, is that when you see the thing, you

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are confronted by the individual substance itself. On seeing it, you no longer have knowledge of the object merely as the postulated occupant of a particular functional role. Your experience of the object, when you see it, provides you with knowledge of the categorical grounds of the collections of dispositions you had earlier postulated. These remarks fill out something of the sense in which conscious attention to an object can provide you with knowledge of the reference of a demonstrative referring to it. Experience of the object can confront you with the individual substance itself, the categorical basis of the dispositional relations in which the object may stand to other things. The question to which I now turn is how to characterize the phenomenal content of experience, so that we can see how it can play this role.

2. Relational vs. Representational Views: the Pane of Glass We can draw a contrast between what 1 will call Relational and Representational Views of the phenomenal character of perception. On a Relational View, the phenomenal character of your experience, as you look around the room, is constituted by the actual layout of the room itself: which particular objects are there, their intrinsic properties, such as colour and shape, and how they are arranged in relation to one another and to you. On this Relational View, two ordinary observers standing in roughly the same place, looking at the same scene, are bound to have experiences with the same phenomenal character. For the phenomenal character of the experiences is constituted by the layout and characteristics of the very same external objects. We have the ordinary notion of a 'view', as when you drag someone up a mountain trail, insisting that he will 'enjoy the view'. In this sense, thousands of people might visit the very same spot and enjoy the very same view. You characterize the experience they are having by saying which view they are enjoying. On the Relational picture, this is the same thing as describing the phenomenal character of their experiences. On what I will call a Representational analysis, in contrast, perception involves being in representational states, and the phenomenal character of your experience is constituted not by the way your surroundings are, but by the contents of your representational states. One way to see the contrast between the two views is to consider the following cases. Suppose that a dagger is hanging in the air before you, and you are looking at it closely. You are visually attending to it. There is a dagger to which you are consciously attending. What can we say to compare and contrast this with the case in which you are having a vivid hallucination of a dagger, and this hallucination is occupying your attention? Just to be fully explicit, the case I

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have in mind is one in which the ordinary case of attention to a dagger is matched as closely as possible by the hallucinatory experience. That is, if the ordinary dagger seems heavy and substantial, so too does the hallucinatory dagger; the hallucination does not, for example, shimmer unduly, or seem any more bloodstained than daggers usually do. On the Representational View, the representational content of your experience may be exactly the same in both cases, so the phenomenal character of your experience may be exactly the same in both cases. Of course, the individuation of representational contents may be thought to depend on factors concerning the environment. But given a single background environment, you could have representational contents relating to daggers and their characteristics whether or not there actually was a dagger in front of you. So the phenomenal character of your experience could be exactly the same in both cases. All that is different between the two cases is the way in which the representational contents are caused on these occasions. In the veridical case, the representations are caused by a dagger. In the hallucinatory case, the representational contents are but creatures of the heatoppressed brain. On the Relational View, in contrast, there is nothing intrinsic in common between the cases in which there is a dagger to which you are consciously attending, and the case in which you are just having a hallucination. In the case in which there is a dagger, the object itself is a constituent of your experience. The experience is quite different in the case of the hallucination, since there is no object to be a constituent of your experience. This way of describing the Relational View recalls so-called 'disjunctive' theories of perception. As put forward by Paul Snowdon, the idea is that we can analyse what it is for someone, S, to have a visual experience as of something being F, by a disjunction. That is, there is no single type of state, 'having a visual experience as of something being F'. The notion of an experience as of something being F covers two quite different types of state. One is the case in which the object is there, and is a constituent of the experience. The other is the merely hallucinatory or illusory state. We are not to think of 'the experience itself as something which could intrinsically be there, just the same, whether the external object existed or not. Snowdon's analysis of 'S has a visual experience as of something being F' was: either there is something which looks to S to be F, or it is to F as if there is something which looks to him (S) to be F (Snowdon 1980-1: 185). The idea is that visual experiences are relational: the object perceived is a constituent of the conscious experience itself. It would not be unreasonable to call this view 'naive realism'. The point of calling it that is to say that on this view, the relation 'S perceives O' is taken as primitive: it is not

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analysed in some such terms as 'O causes S to have an experiential content as of something's being F'. Any such naive realism has a striking implication for the way in which we think of the relation between cognitive processing and experience of objects. Notice first that there is a sense in which cognitive processing is a 'common factor', an element found in both veridical and hallucinatory processing. Whether or not there is an external object being seen, the same features may be located on just the same feature maps, and they may be bound together in just the same way. Now those familiar with scientific work on vision sometimes assume that consciousness of the world is what happens when at some stage in the cognitive processing, the contents being processed acquire the extra dimension of being 'subjectively available'. The tendency is to suppose that it is the very same contents that are cognitively processed as figure in the contents of consciousness (cf. Marr 1982: 73). This way of thinking of things carries with it an immediate commitment to the 'common factor' view of perception. Since the cognitive contents function as common factors, the experiential contents will be common factors too, exactly the same whether the external object exists or not. If, though, the Relational View is correct, we should not think of the experiential contents as common factors. We have to think of the external object, in cases of veridical perception, as a constituent of the experience. On a Relational View of perception, we have to think of cognitive processing as 'revealing' the world to the subject; that is, as making it possible for the subject to experience particular external objects. Without the cognitive processing, there would be no experience of the objects; without a solution to the Binding Problem by the cognitive system, there would be no experience of objects. But without the objects, there would be no experience of objects either. On the Relational View of experience, we have to think of experience of objects as depending jointly on the cognitive processing and the environment. Experience, on this view, cannot be understood simply as a matter of cognitive contents becoming subjectively available. There are some analogies that might help in dispelling the idea that the existence of cognitive processing in vision establishes the correctness of a Representationalist View of experience (for an unusually explicit statement of that idea, see Smythies 1999). One analogy is that the Relational View thinks of perception as like viewing the world through a pane of glass. It would plainly be a mistake to hold a Representationalist View of panes of glass: to hold that the only way in which it can happen that you see a dagger through a pane of glass is by having a representation of a dagger appear on the glass itself. (This representation on the glass would be a 'common factor' which could be there whether or not there really was an external dagger.) So the analogue of a Relational View for seeing through

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windows is surely correct. But, the intuition runs, the existence of cognitive processing is incompatible with the 'glass' model: the whole point about looking through a window is that the window does not have to construct a representation of the world outside. But what the study of the brain tells us is that in vision, the brain is actively involved in constructing a representation of the world. Therefore, following this line of thought, we have to abandon the 'pane of glass' model. The obvious alternative model is the television set, which does indeed laboriously construct an image from the information input to it. Now both these models are homuncular—they implicitly appeal to the perceiver who is looking at the scene through the glass, or on the screen. So neither of these models should be taken too seriously. But if you are caught by the idea that the existence of brain processing in vision means that a Representationalist View must be correct, it may be helpful to consider another analogy. Suppose we have a medium which, like glass, can be transparent. But suppose that, unlike glass, it is highly volatile, and needs constant adjustment and recalibration if it is to remain transparent in different contexts. Suppose, in fact, that the adjustment required is always sensitive to the finest details of the scene being viewed. The upshot of the adjustment, in each case, is still not the construction of a representation on the medium of the scene being viewed; the upshot of the adjustment is simply that the medium becomes transparent. You might think of visual processing as a bit like that. It is not that the brain is constructing a conscious inner representation whose intrinsic character is independent of the environment. It is, rather, that there is a kind of complex adjustment that the brain has to undergo, in each context, in order that you can be visually related to the things around you; so that you can see them, in other words. If we think of visual processing in this way, we can, of course, acknowledge that the adjustment and recalibration may not always yield full transparency. You may, for example, be looking at the world with a jaundiced eye, so that everything you see seems to have a yellowish cast. In that case your visual experience would not have exactly the same content as the visual experience of an ordinary observer looking at the same scene. But this point does not tell in favour of a Representational view; it is entirely consistent with the Relational View. The scene through a pane of yellowish glass will be different to the scene through a pane of purely transparent glass. That does not show that in either case the transparency should be understood as a matter of a representation being inscribed on the glass. It is just a mistake to suppose that the Relational View is undermined by the fact that the idiosyncracies of the perceiver may affect phenomenal content. You might wonder whether the idea of an egocentric frame of reference

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for conscious vision is consistent with the Relational View. But the Relational View says only that the qualitative character of conscious experience is constituted by the characteristics and layout of the objects one is seeing. It is consistent with that to say that only certain of their characteristics constitute one's experience of them. For example, hidden characteristics of the objects will play no role in constituting one's experience of them. Hence, the egocentric spatial layout of the scene may play a role in constituting the qualitative character of one's experience of the scene. So long as the ordinary notion of a 'view' is coherent, it is coherent to suppose that the egocentric layout of the scene could constitute the content of someone's experience of it. Consequently, we can maintain a Relational View of experience but still hold that conscious attention singles out its targets in a way that is commensurable with the underlying information-processing used in verifying and acting on the basis of propositions about a demonstrated object.

3. The Argument from the Explanatory Role of Experience Since both the Relational and Representational Views of the phenomenal character of experience have to be taken seriously, and since they cannot both be correct, how are we to decide between them? Both views will say that they give immediately recognizable descriptions of ordinary experience. Neither view is likely to generate a direct contradiction with some fact of ordinary experience. So how are we to decide? I think that the only way to proceed is to ask why we need the notion of the phenomenal character of experience. We have to look at the role that the notion plays in our reflective thinking, we have to ask what the point is of the notion. I have been arguing that experience is what explains our grasp of substantial objects. Something like this view is implicit in recent arguments for a disjunctivist view of experience. As we saw, on a disjunctivist view of experience, there is no experiential factor in common between the case in which you see an object, and the case in which you have a hallucination of such an object. When you see an object, the object itself is a constituent of your experience. The argument for this view is given by John McDowell in these words (he refers to the common factor view as the 'Cartesian' view): The threat that the Cartesian picture poses to our hold on the world comes out most dramatically in this: that within the Cartesian picture there is a serious question about how it can be that experience, conceived from its own point of view, is not blank or blind, but purports to be revelatory of the world we live in. (McDowell 1986: 152)

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This argument is very briefly stated, but it is intriguing. The argument presses very hard the idea that experience of objects has an explanatory role to play. Experience of objects has to explain how it is that we can have the conception of objects as mind-independent. The objection to the common factor view is that on it, experience of objects could not be what explains our having the conception of objects as mind-independent. There is something intuitive about this. On the common factor view, all that experience of the object provides you with is a conscious image of the object—the image which bears the representational content. The existence of that conscious image is in principle independent of the existence of the external object. The existence of the image, though, is dependent on the existence of the subject who has the conscious image. So if your conception of the object was provided by your experience of the object, you would presumably end by concluding that the object would not have existed had you not existed, and that the object exists only when you are experiencing it. We cannot extract the conception of a mind-independent world from a mind-dependent image. It seems as though it ought to be possible, though, to extract the conception of a mind-independent world from an experience which has a mind-independent object as a constituent, which is what the Relational View ascribes to us. I think that this is the intuitive argument to which the disjunctive view is appealing. I think it has some immediate force, but there are some issues that need further discussion here. It is striking how hard the explanatory role of experience is being worked. You might have thought that the immediate response of a common factor theorist to this argument is that the image provides the conception of an objective world simply by displaying the world as objective. Even if I am hallucinating, the objects I seem to see, seem to be mind-independent objects. So a common factor image can present objects as mind-independent; and surely that is all that is needed. The problem with this reply is that it takes for granted the intentionality of experience. That is, it takes it for granted that experience of the world is a way of grasping thoughts about the world. To see an object is, on this conception, to grasp a demonstrative proposition. There are many ways in which you can grasp a proposition: you can grasp it as the content of speech or as the meaning of a wink or a sigh. One way in which you can grasp a proposition is as the content of vision. The common factor theorist says that ordinary vision involves grasping demonstrative propositions as the contents of experiences. And you could grasp such propositions whether or not the external objects exist. The disjunctive theorist might reply that this simply begs the question; the disjunctivist's view is, after all, that you cannot grasp demonstrative propositions whether or not the external objects exist. But the disjunctivist

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was trying to state an objection to the common factor view, so an attempt to shift the burden of proof at this point is simply giving up; the two views are equally probable. Anyhow, the disjunctivist has a better reply. The argument turns on an appeal to the explanatory role of experience. Experience is what explains our grasp of the concepts of objects. But if you think of experience as intentional, as merely one among many ways of grasping thoughts, you cannot allow it this explanatory role. Suppose someone said: 'Actually, reading newspapers is the fundamental way in which you understand the concepts of a mind-independent world. All your conceptual skills depend on your ability to read newspapers.' The natural response to this would be that reading newspapers does indeed involve the exercise of conceptual skills, but it is simply one way among many of exercising those conceptual skills. Just so, if all there is to experience of objects is the grasping of demonstrative thoughts about them, then experience of objects is just one among many ways in which you can exercise your conceptual skills. At this point we do not have any way of explaining why there should be anything fundamental to our grasp of concepts about experience of objects. It is when we press the explanatory role of experience like this that we can see the force of the disjunctivist's argument. We are not to take the intentional character of experience as a given; rather, experience of objects has to be what explains our ability to think about objects. That means that we cannot view experience of objects as a way of grasping thoughts about objects. Experience of objects has to be something more primitive than the ability to think about objects, in terms of which the ability to think about objects can be explained. The question now is whether the common factor picture of experience provides a view of experience on which it could be what explains our ability to think about objects. And at this point the question whether something essentially mind-dependent could provide for the conception of a mind-independent world really does seem forceful. Yet once we have reached this understanding of the argument, we can see that there is also something wrong with the formulation of disjunctivism given by McDowell (1986) and Child (1994). For they take it for granted that the way in which to state the disjunctivist view is as the view that experience involves the grasping of demonstrative thoughts about objects, together with the claim that those demonstrative thoughts are object-dependent. But that robs experience of its explanatory role, and disjunctivism becomes no better placed than the common factor view to acknowledge the role of experience in explaining how we have the conception of the world that we do. Since disjunctivists do take experience of objects to be intentional, I am talking instead of the 'relational' view of experience as being what is motivated by the above line of argument. On the Relational View, experience of

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objects is a more primitive state than thought about objects, which nonetheless reaches all the way to the objects themselves. In particular, experience of an object is what explains your ability to grasp a demonstrative term referring to that object. To sum up the point of this section: as disjunctive theories of perception have been developed in the literature after Snowdon's article, the content of the experience is generally taken to be a demonstrative proposition; and the claim that the object is a constituent of the experience is taken to amount to the idea that the object is a constituent of the proposition which gives the content of the experience. The suggestion is that the qualitative character of the experience is exhausted by this object-dependent propositional content. But if we think of the matter in this way, then experience can play no role in explaining how it is possible for us to understand propositions about our surroundings. Experience of objects simply presupposes, and so cannot explain, our ability to think about objects. Disjunctive theorists may object that it was never part of their ambition to give this kind of explanatory role to experience. But this would not be a convincing reply. The argument for the disjunctive theory, in so far as there is a good argument for it, is just that if you deny the disjunctive theory and think of visual experience as the 'common factor' between cases of hallucination and cases of veridical perception, then you rob experience of its explanatory role (cf. McDowell 1986). As Bill Child puts it: to think of conscious experience as a highest common factor of vision and hallucination is to think of experiences as states of a type whose intrinsic mental features are world-independent; an intrinsic, or basic characterization of a state of awareness will make no reference to anything external to the subject. But if that is what experience is like, the disjunctivist objects, how can it yield knowledge of an objective world beyond experience, and how can it so much as put us in a position to think about such a world? (Child 1994:146-7)

Without arguing the point here, I do want to suggest that the argument that knowledge would not be possible, on the common factor approach, is not the fundamental issue; the common factor theorist could as readily as anyone else define a notion of 'knowledge' which more or less matched the ordinary concept. For example, there is no evident difficulty in the idea that a common factor image could be a reliable sign of an external phenomenon; if you already have the concept of that phenomenon, there is no particular difficulty about using a reliable sign of it to give you knowledge of it. The fundamental objection to the common factor approach is that on the common factor approach, experience cannot play its explanatory role; we cannot understand how experience, so conceived, could be what provides us with our concepts of the objects around us. As Child puts it, 'to

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conceive of experience in such terms is to make it unintelligible how our experience could put us in a position to ... think about an objective, mindindependent world' (1994: 149). But the crux is that if you demand that experience should play that explanatory role, you also lose the right to think of it as exhausted by its conceptual content. For if there is no more to visual experience than the grasping of propositions, then you are still in no position to appeal to vision in explaining how it is that we are able to think about the world around us.

4. Violations of the Explanatory Role of Experience There are views of the content of perception which straightforwardly violate the explanatory role of experience. For example, some philosophers say that perception does not represent particular objects at all. What drives such a view is the idea that your perceptual experience could be exactly the same even if the particular object you are observing were replaced by another, qualitatively indistinguishable object. Thus Martin Davies writes: 'if two objects are genuinely indistinguishable for a subject, then a perceptual experience of one has the same content as a perceptual experience of the other' (Davies 1997: 314; cf. Evans 1982). So if you and I are in exactly similar prison cells, looking at exactly similar scenes, and both thinking, 'That cup is empty', our perceptions have exactly the same content. Since we are looking at different particular objects, it follows that neither your perception nor my perception is representing those particular things. That is not to say that our perceptions are not representing the world at all: Davies suggests that 'One way to see how perceptual content can be truth conditional, although not object-involving, is to take perceptual content to be existentially quantified content' (1997: 314). So you and I both have perceptions which represent it merely that there is a cup of a particular type on top of a tray, and so on. The trouble with this is that, as Davies acknowledges, when you say 'that cup' you know which cup you are talking about, and when I say 'that cup', I know which cup I am talking about. So what is the source of this knowledge? The natural answer is that it is your experience of the cup that provides you with knowledge of which cup is in question. But on this picture of perceptual content, perception could not provide you with knowledge of which particular thing you are talking about. The whole point of the view is to insist that consulting perception will only provide you with a number of existential propositions, to the effect that there is, for example, a cup of a certain type on a tray, without ever getting down to brass tacks and telling you which cup it is that is on top of which tray. So no amount of

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looking to see could provide you with knowledge of which cup is being talked about. It is, therefore, entirely obscure how you could have achieved knowledge of which cup is in question. A different view of the content of perception is set out by Tyler Burge (1991). Burge uses the idea that there are 'demonstrative elements' in the content of perception. A 'demonstrative element' can be as it is, whether or not it refers to an object, and independently of which object it refers to. The reference of a particular demonstrative element is fixed by the context of the perception in which it occurs. In different possible contexts, one and the same demonstrative element would refer to different external objects, or to no object at all (Burge 1991: 208). Unlike Davies, Burge's view does find a place for the representation of particular objects in experience. Can this view acknowledge the role of experience of objects in making it possible for us to think about objects? On the face of it, this view is open to exactly the same problem as we saw facing the disjunctivist. It ascribes an intentional content to perception, but gives no explanation of how it is that we are able to grasp that intentional content. Consequently, it does not seem that the view can explain why experience of the world is fundamental to our ability to think about the objects around us. Experience of objects has simply itself become one among many ways of thinking about objects. So it does not seem capable of explaining how thought about objects is achieved. You might reply that the demonstrative element is not to be regarded as something that is itself immediately involved in thought about the object; it belongs to a category of perceptual representation that is more primitive than thought, and therefore it can play an explanatory role here. But the move to thinking in terms of 'non-conceptual' content does not help. The explanatory role of the perception is still limited. All that is within the perceiver's subjective life is the demonstrative element itself. The aspects of context which fix the reference of a particular demonstrative element on a particular occasion are not themselves to be assumed to be available to the subject (Burge 1991: 203-6). The thing that is subjectively available—the demonstrative element—cannot of itself, therefore, distinguish between presentation of one object and presentation of another. Nor can it, of itself, provide an assurance that the demonstrative refers at all. It is, therefore, opaque how the demonstrative element could provide the subject with an understanding of the demonstrative term. The demonstrative element itself could not provide knowledge of what the term refers to. The only way to supplement the picture, to provide the subject with knowledge of what the demonstrative element is referring to in this context, would be to provide the subject with knowledge of the context in which the demonstrative element is occurring. But this knowledge will evidently not be provided by

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the initial perception of the object itself, on Burge's account, nor does it seem likely to provide a demonstrative identification of the thing, rather than a description of it. So Burge's picture of the content of experience cannot acknowledge the role of experience of objects in explaining our understanding of demonstratives. I think that one powerful reason for resistance to the Relational View of experience is the thought that to characterize the content of an experience, it cannot be enough simply to say which object is being experienced: you must also say how the object is being experienced, you must characterize the way in which the object is being perceived by the subject. After all, two people could be seeing the very same object, and yet the intrinsic character of their experiences be quite different. This in itself is undeniable. It is the next step that leads to rejection of the Relational View. The next step is to say that the way in which the object is given is independent of whether the object exists, and independent of whether the subject is experiencing one or many similar objects. On the Classical View I outlined in Chapter 1, though, the way in which you are given an object has to be what causes and justifies the pattern of use that you make of the demonstrative. But for the way in which you are given the object to justify the use that you make of the demonstrative, it really matters whether there is an object there at all, and if so, whether it is one or many. If, as on the Classical View, ways of being given objects are to be individuated in terms of which patterns of use they cause and justify, then which way of being given an object is in question is not something that is indifferent as between the cases in which there are many, one, and no objects there at all.

5. Existence and Uniqueness To see how to develop the appeal to the explanatory role of experience, suppose for a moment that you take it that the logic of demonstratives is not a free logic; that is, that the mere occurrence of a demonstrative in an atomic proposition, or the negation of an atomic proposition, is enough to allow us to infer the existence of the object. So from the proposition, 'It is not the case that that tree is on fire', you can infer that there is something which is not on fire. An account of knowledge of the reference of 'that tree' has to explain how you know that there is such a thing. The problem for the common factor view is that the conscious experience to which it appeals, being the factor common to the veridical and the hallucinatory cases, is something that would be as it is whether or not the reference of the demonstrative existed. So it does not seem that conscious experience, conceived as

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on the common factor view, could be what explained your grasp of the validity of the transition from 'It is not the case that that tree is on fire' to 'There is something which is not on fire'. In contrast, consider the Relational View, on which the object itself is a constituent of your conscious experience as you attend to the object. Since the conscious experience has the object itself as a constituent, it has as a constituent the object whose existence is what makes the existential generalization true. So when you interpret the demonstrative in the premise by consciously attending to the object, this interpretation is one that guarantees the truth of the existential generalization. On this picture, someone who uses a demonstrative term which does not refer is in something like the position of a person who uses a logical connective for which there is no truth-table. So, for example, consider someone who uses a sign '*' subject to the following rules of inference: A

B

A*B A*B A

And those are all the rules of inference. In particular, you cannot, from A*B', infer B. You can only infer A. So there is no truth-table to be drawn for this sign. Any truth-table which explains why verification of A*B' requires that you have both A and B, will have to say that the truth of 'A*B' requires the truth of A and the truth of B. But then the truth-table will validate the elimination rule, that from 'A*B' you can infer B, as well as the rule that from 'A*B' you can infer A. So if you ask, 'What does "*" mean?', the only answer is that it has no meaning. Someone who uses such a sign has just made a mistake: they think it has a meaning when it has none. Now it is certainly arguable that someone who uses such a sign as '*' must have made some kind of error of rationality: just thinking about the situation ought to have been enough to allow them to see the mistake. So there is a marked contrast here with the case of demonstratives. Even if you are maximally rational, it can, in principle, happen that you are the victim of hallucination or radical perceptual illusion, and so suppose that a demonstrative refers when in fact it does not. But while that is indeed an important contrast, the situation of someone who uses a demonstrative even though it refers to nothing is still formally the same as that of someone who uses a logical connective for which there is no truth-table. Any account of our understanding of logical connectives must, on a classical account, explain how it can be enough to guarantee knowledge of the existence of

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the truth-table; and any account of our understanding of demonstratives must, on a view which rejects free logic, explain how an understanding of the demonstrative can be enough to guarantee the existence of the object. Since experience of the object is what provides you with your understanding of the demonstrative, that experience must be enough to guarantee the existence of the object, which is just what the Relational View provides. In the case of a logical constant, on a Classical View of the matter, understanding the term requires that you know the truth-table for the term; that you know which truth-table it has. It would not be enough, for an understanding of the logical constant, merely that you have grasped something which is reliably though not invariably correlated with the existence of a truth-table for the term. If we accept that the assignation of a reference to a demonstrative is to be thought of in parallel to the assignation of a truth-table to a propositional constant, then an understanding of the demonstrative will not be provided merely by grasp of something which is reliably correlated with there being a reference for the term. To understand the demonstrative you will need to know which thing it refers to. This understanding has to be provided by your experience of the object. So experience of the object has to be enough to guarantee that the object exists. It will not be enough, for understanding, merely that you have an experience which is reliably though not invariably correlated with the existence of a reference for the demonstrative. So only experience, conceived as on the Relational View, in which the object figures as a constituent of the experience itself, will be enough for an understanding of the demonstrative. Experience, conceived as on the 'common factor' view, could not provide an understanding of the demonstrative. Of course, whether existential generalization is always valid over a position occupied by a demonstrative depends on what the right account is of what it is to understand a demonstrative. I have so far simply been following through on what the shape should be of an account which licenses existential generalization; an account on which understanding a demonstrative is a matter of knowing what it stands for. There is, though, another family of inferential transitions with which the common factor account seems likely to have difficulty. The ordinary use of a demonstrative may depend on your ability to keep track of an object, whether across time or across sensory modality. There are some cases in which this is strikingly obvious. Suppose, for example, that someone is clothed in black, and operating against a dark background while plunged in darkness, except for some low-intensity lights fastened to her clothes. At any one moment, the instantaneous visual array reveals only a random assortment of lights. But it is a familiar fact that when you watch this person move and act, it is quickly apparent that it is a person that you are watching, and indeed other

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facts about the person, such as their age and sex, may be readily apparent (Johansson 1973; Runeson and Frykholm 1983). Here you can use the demonstrative, 'that woman', and your use of the term depends on temporally extended observation; a momentary observation would yield only the random array of lights. Or again, suppose you consider someone who is playing a guitar and thinking, 'This guitar is going out of tune', so pausing to adjust the tuning. Here it is essential to the whole operation that the demonstrative 'this guitar' refers to something of which you have visual, tactual, and auditory information. The problem now is that on the common factor approach, when you consider what is involved in keeping track of the object across time, or across sensory modality, it seems that it will have to involve different sensory presentations that, moment by moment, or from modality to modality, are being used to interpret the demonstrative. These sensory presentations cannot in themselves guarantee that you are succeeding in keeping track of the thing from modality to modality, or from moment to moment. After all, on the common factor account, you could have exactly the same sensory presentations whether or not there was an object there at all; and certainly you could, on this view, have the same sensory presentations even though you were not in fact managing to keep track of a single object, but were encountering different things from moment to moment, or from modality to modality. The problem now is not existence but uniqueness: the problem is not that there may be reference failure, and nothing being talked about, but too many objects which are candidates for being the reference of the term. (The parallel would be with a logical constant whose rules for use underspecify the meaning of the term, so that there are different truth-tables which would all validate those rules for use.) In consequence of this, there are certain basic patterns of inference involving demonstratives whose correctness cannot be grasped by someone interpreting the demonstrative by means of conscious attention to the object, if 'conscious attention' is conceived on the common factor model. For example, there is the Temporal Case, in which the two premises state knowledge which depends on you having kept track of a single thing: That woman is running; That woman is jumping; Hence, that woman is running and jumping. Recognizing the validity of the inference requires that your experience should make the sameness of the object transparent to you; but, on the common factor conception, that is precisely what your experience of the object cannot do. On the common factor conception, your experience of the object would have been exactly the same whether there was one woman

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there throughout, or many, or none. So your experience in itself, on the common factor picture, can provide no guarantee of the sameness of the object throughout. Similarly, consider the Cross-Modal Case, in which the two premises depend on you having kept track of a single object from sensory modality to sensory modality: This car is going quite slowly; This car is rattling; Hence, this car is going quite slowly and rattling. Again, the validity of the inference cannot be guaranteed by conscious attention to the object, as conceived on the common factor model, because that would not be enough to secure the existence and uniqueness of the car in question. Experience of the object, conceived on the Relational model, in contrast, does have the capacity to make the validity of these inferences comprehensible to us; it makes existence and identity over time and across sensory modality transparent to us. Of course, the Relational View has to acknowledge that consciousness of the object, across time or across sensory modality, depends on using fallible cognitive mechanisms. It may seem to you that you have kept track of just one thing when in fact you have not. Perhaps one object was substituted for another in the twinkling of an eye, or the guitar you were listening to was not in fact the one you are holding. But that does not show that you are in the same conscious state whether or not it is the same object; rather, it shows that it may be impossible to tell, simply by having the experience, which sort of experience it is—whether it is one that involves a single object, or if it is, rather, an experience that involves a multiplicity of objects. In the case of inferences involving extended observation of the object, or access to the object through different sensory modalities, there is a reliance on the visual system's capacity to bind together different features of the same object across time or across sensory modality. But in order to explain our grasp of the validity of the inferences involved in the Temporal or Cross-Modal Cases, it is not enough merely that there should be this reliable work of binding going on at some sub-personal level. It must be transparent to the subject that it is one and the same thing that is in question, across time and across sensory modality. So the upshot of the binding has to be an experience involving the object in which the identity of the object is transparent to the subject. This must not be thought of as a matter of the subject having a further representation to the effect that it is one and the same object there over that period, or in different sensory modalities. The whole point of saying that the object itself is a constituent of the experience is to finesse such ques-

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tions about how the object is being represented; otherwise, as we saw, we face considerable difficulty in explaining how the conception of the object itself, as a substantial thing, can be made available to the subject by experience of the object. Rather, what we can say is that the subject's experience can make it manifest to the subject that it is one and the same object that is in question over a period of time, and that the possibility of such a state is explained by the possibility of the underlying information-processing. This is not to say that the subject can claim to know the falsity of various sceptical hypotheses (for example, relating to unobserved multiple substitutions of one object for another over a brief period). For the subject might not be able to differentiate his current experience from the experiences he would be having were the sceptical hypotheses true. But given that the subject is experiencing the same object over a period, he may nonetheless have the right to engage in inferences which trade on identity across time or across sensory modality. It may be, also, that the role of binding parameters in the case of a canonical confrontation with the thing is just to make apparent the categorical unity of the thing. That is, the particular binding parameters used by the visual information-processing system may have the function of exhibiting the object as a categorical unity, when we consider the impact of this style of binding on the content of the subject's experiences.

7 The Explanatory Role of Consciousness 1. Consciousness as Higher-Order Thought I am pursuing the question: how must we think of experience of objects, if experience of an object is to be what provides you with your knowledge of the reference of a demonstrative? When we are given any analysis of what consciousness is, one way in which we can test such an analysis is by asking: if this is what it is to experience an object, could that be what explains your knowledge of the reference of a demonstrative? Suppose we look briefly at the account of consciousness as higher-order thought provided by David Rosenthal (1997). According to Rosenthal, a mental state is conscious just in case it is accompanied by a non-inferential, non-dispositional, assertoric thought to the effect that one is in that very state. So, in particular, suppose we ask what the difference is between a conscious perception and a perceptual state which is not conscious. In general, says Rosenthal, a perceptual state's being conscious consists in its having two sorts of properties: sensory qualities—such as sensory redness, in the case of vision, or throbbing, in the case of a pain—and the property of being conscious. A state can have sensory qualities but fail to be conscious, because there is no accompanying thought to the effect that one is in that very state. According to Rosenthal, that is exactly what happens in cases of blindsight. The blindsighted subject has the perception with the sensory qualities, but does not have the higher-order thought to the effect that he is in that very perceptual state. Of course, this higher-order thought need not itself be conscious; for the higher-order thought to be conscious you would need to have a further thought, about that higher-order thought, and in general we do not usually attend to our own higher-order thoughts. So it is in virtue of your unconscious higher-order thought, to the effect that you are having a particular perception, that the perception itself can be said to be conscious. Is this the kind of description of consciousness that would allow us to

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see how consciousness of a perceived object could be what explains knowledge of the reference of a demonstrative? On this view, consciousness of the perceived object would be a matter of (a) perceiving the object, and (b) that perception being a conscious perception. What makes the perception conscious is that you have a higher-order thought to the effect that you are having that perception. But the theory has to be developed somewhat. Which aspects of the perception are conscious will depend on exactly which higher-order thought you have about your perception. This is how Rosenthal explains the way in which acquisition of new concepts can affect your conscious experience. Gaining new concepts means that you can have a wider range of higher-order thoughts about exactly which perceptions you are having, so that a wider range of aspects of those perceptions can be conscious. So how is the fact that the perception is a perception of that very object to be reckoned into consciousness? The only way in which we can get that effect, on Rosenthal's theory, is by saying that the higherorder thought you have, to the effect that you are having a perception, is a thought that your perception is a perception of that very object. The higher-order thought itself, then, must use a perceptual demonstrative referring to the object. The immediate problem now is that this notion of 'consciousness of the object' seems to provide us with nothing in the way of an explanation of how it is that we have knowledge of the reference of the demonstrative. 'Consciousness of the object' consists in perceiving the object together with having a thought to the effect that one is perceiving that very object. But 'having a thought to the effect that one is perceiving that very object' presumes that you understand the demonstrative vised to refer to the object; that is the only way you have of singling out the object you are identifying. So this account simply presupposes the phenomenon we are trying to explain. That is, it simply presupposes knowledge of the reference of the demonstrative, and cannot explain how you have knowledge of the reference of the demonstrative. It would, incidentally, by no means be an adequate response to this point to say that we must, instead of higher-order thoughts, appeal to the 'qualia' or sensational properties that the perception has, in explaining what it is to be conscious of an object. For that move does not of itself let us see why consciousness of the object should be what explains the capacity to think demonstrative thoughts about it. To give an analogy: there are the bases on which we find out about whether something is carrying an electric charge (is it plugged in? and so on). And there are the consequences we draw from a judgement that something is carrying an electric charge (it should work fine if we switch it on now). You might grasp all these procedures, without knowing anything about what electricity actually is.

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Straight off, if that is your condition, it would not at all be alleviated by giving you an electric shock, so that you can find out about the qualia associated with electricity. Similarly, suppose we consider the blindsighted subject, who is using something like the ordinary ways of finding out about whether a line is horizontal or vertical, and so on, and something like the ordinary ways of reaching for and grasping an object in his blind field. He does not know which object he is thinking about. Consciousness of the object is what would make the difference. But how could consciousness of the object be what mattered? On the 'qualia' picture, it does not seem that it could help at all. All consciousness provides, on this picture, is knowledge of, as it were, the kind of shock that the object can produce; it does not provide any grasp of which thing it is.

2. Use vs. Knowledge of Reference: Functionalism In general, as we have seen, we can distinguish between knowledge of the reference of a term, and knowledge of how to use the term. Knowledge of how to use the term includes the ability to use propositions involving it in deductive reasoning, and it includes knowledge of how to verify propositions involving the term and knowledge of how to act on the basis of propositions involving the term. On a classical view, these patterns of use are not arbitrary. You use the term in the way you do because you know what it stands for. Your use of the term is causally explained by your knowledge of what it stands for. Moreover, the way in which you use the term is justified by your knowledge of what it stands for; the pattern of use that you make of the term can be justified or criticized by appeal to your knowledge of the reference of the term. This means that there is an immediate danger for any attempt to provide a functionalist analysis of consciousness of objects. The problem is that one natural form for a functionalist account of experience of objects to take is this: experience of the object, you might say, is on a functionalist analysis no more than the ability to verify propositions about the object, or to act suitably on the basis of propositions about the object. All it comes to, that you have experience of the object, is that you can make suitable use of your representations of the object. If, however, our framework is correct, that kind of functionalist analysis of what it is to experience an object would already be making a mistake. We need the notion of experience of an object in explaining how it is that we know the reference of a demonstrative. And knowledge of the reference of a demonstrative is what explains the use that you make of the term; you use the term the way you do, because you know what it stands for. But on

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this functionalist analysis, experiencing the object is the very same thing as having a collection of dispositions to use a demonstrative term in various ways. So we would lose the explanations. We would lose the right to say that use of the term is explained by knowledge of reference, which in turn is explained by experience of the object. This does not mean that I am giving a functionalist analysis of what it is to be conscious of an object. I am saying that consciousness of an object does have a functional role to play; and any characterization of what it is to be conscious of an object must acknowledge that consciousness of objects has that explanatory role. But this view stands in opposition to the idea that all there is to being conscious of an object is being able to use the demonstrative term correctly. On the contrary, since consciousness of the object has to be what explains your ability to use the demonstrative term correctly, it cannot be identified with the ability to use the demonstrative. This is not to say that functionalist analysis is altogether impossible, but it is not going to be easy to find a functional characterization of experience of the object which will acknowledge the point that experience of the object is what explains the pattern of use that you make of a demonstrative term, rather than merely identifying experience of the object with the tendency to engage in that pattern of use. Your experience of the object has to be what ultimately explains your ability to verify propositions about that thing, and to act on the basis of propositions about that thing. Suppose that, in this light, we consider Daniel Dennett's early 'Cognitive Theory of Consciousness' (1981), in which he famously presented a flow-chart for consciousness. Since we are specifically concerned with experience of objects and its role in our understanding of demonstratives, what particularly concerns us are the relations between the areas Dennett labelled 'Perceptual Analysis', 'M' (a short-term memory store), 'Control', and ' PR' (an area that confirms which speech-acts to execute). The centre of the system is dialogue between Control and M. The idea is that Control may in effect interrogate short-term memory for the answers to questions in which it is interested (the reasons for the interest not themselves being explained in this model); short-term memory has input from both perceptual analysis and a problem-solving module. The answers that Control receives from short-term memory may in turn lead to activation of PR, so that there is in the end production of speech. Dennett's view now is that this characterizes all that there is to being conscious. In particular, consciousness of objects would be a matter of having input from perceived objects as part of the content of short-term memory (Dennett 1981: 169). The common-sense objection to this model is stated by David

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Chalmers: ' it tells us nothing about why there should be something it is like to be a system undergoing these processes' (Chalmers 1996: 114). Dennett's reply to this objection is not difficult to see. It is that there is something it is like to be a system undergoing these processes. According to Dennett, 'we find ourselves wanting to say all these things about what is going on in us; this gives rise to theories we hold about how we come to be able to do this—for instance, the notorious but homespun theory that we "perceive" these goings on with our "inner eye", and that this perception grounds and explains the semantic intentions we have' (Dennett 1981: 166-7). The idea that there is something left out by the model is just a mistake. So long as the debate remains at this point there is simply no way of making progress. A similar point applies to Dennett's characterization of consciousness in Consciousness Explained (Dennett 1991). This, too, is a description, albeit a more complicated description, of how perceptual input can ultimately control the production of speech. Dennett's opponents think it is simply obvious he has left something out; Dennett himself thinks all that has been 'left out' is something that theorists mistakenly postulate as the basis of introspection. The only way to reach a point at which we can adjudicate the issue is by asking why we need the notion of consciousness at all. I have been arguing that we need the notion of consciousness in explaining how it is that we have knowledge of the references of demonstrative terms. Knowledge of reference in turn has to explain the use that we make of demonstrative propositions: how we verify them and how we come to act on the basis of them. So when we look at a characterization of consciousness, we have to ask whether what is being described could play this explanatory role. Now the model Dennett describes obviously contains enough machinery to constitute an ability to verify demonstrative propositions, and could be extended to include the ability to act on the basis of demonstrative propositions. But that grasp of use is not to be identified with consciousness of the object; it is a consequence of consciousness of the object, rather than being identical to it. So is there anything in the model that could provide the explanation of this grasp of the use of the demonstrative? The only other feature we have in the model is the ability to provide introspective reports of what one is seeing and so on; but these reports will typically themselves involve the use of demonstratives, and hence, just as in the case of Rosenthal's theory, they cannot be what explains our capacity to use the terms. There is, therefore, nothing in this kind of model that can be thought of as providing the knowledge of reference that grounds our use of demonstrative terms. Consequently, we have to conclude that consciousness of objects has indeed been missed out here.

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I have said that experience of the object is what provides knowledge of the reference of a demonstrative, and that this experience of the object is in turn what causes and justifies the use of particular procedures to verify and to find the implications of a demonstrative proposition. As we saw, that is already enough to challenge a simple functionalist analysis of 'experience of the object', which directly equates experience of the object with the ability to verify and to find the implications of propositions about the thing. But we can further ask: what is it about experience of the object that allows it to play this causing and justifying role? In particular, we can ask: what characterization do we need of the content of experience if we are to understand how it can play this causing and justifying role? I want to propose that we experience properties as categorical, rather than merely as complexes of dispositions, and we experience objects as categorical, rather than merely as complexes of functional connections. And this is one of the reasons why experience has the role that it does. We do not experience objects merely as: things which can be found out about thus and so; and we do not experience objects merely as: things which can be acted on thus and so. We experience objects as the categorical grounds of the possibility of verification thus and so, and as the categorical grounds of the possibility of action thus and so. That is why experience of the object provides a knowledge of reference that can cause and justify the use of particular procedures to verify and to find the implications of a demonstrative proposition. We can give a rough summary of the view of the content of experience that we need here by saying that experience should be regarded as experience of the categorical. This is a condition on any analysis of the phenomenal content of experience. For future reference, let me state this as the Intrinsicness Condition: The Intrinsicness Condition: Experience is experience of the categorical. We can think of property of an object, such as roundness, as issuing in the possession by the object of a complex of dispositions, such as a tendency to roll in suitable circumstances. And we can think of object identity as grounding a complex of dispositions, such as a tendency to transmit marks over time. The Intrinsicness Condition says that experience of objects and their properties is in general experience of the categorical, rather than merely experience of the related complexes of dispositions. In section 4 of this chapter, I will argue that the Intrinsicness Condition demands what I earlier called a Relational View of experience. First, though, in section 3 I want to say something more about what the Intrinsicness Condition is and why it seems compelling.

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Why do we need the notion of the phenomenal character of experience? We have to look at the role that the notion plays in our reflective thinking, we have to ask what the point is of the notion. For example, if we are presented with an analysis of the phenomenal character of pain, we have to remember that pain is awful: we have to remember that pain is a source of concern and that we think it right to try to nullify pain where we can. If we are told, for instance, that being in pain is a matter of being in a particular kind of representational state, we have to ask why being in such a representational state should be awful; we have to ask what it is about this kind of representational state that means we should try to nullify it. I have argued that we use the notion of experience of an object—or more precisely, conscious attention to an object—in explaining how it is that we have knowledge of the reference of a demonstrative. As we have seen, this point by itself means that we cannot endorse the view of consciousness as higher-order thought, or the conception of consciousness provided by a simple functional characterization. But there is still a further question to ask. That is: why should it be experience of the object that is playing this explanatory role? What is it about the notion of experience of an object that means it is suited to explaining our knowledge of reference? To understand this, we have to look more critically at the notion of knowledge of the reference of a demonstrative. What is it to know which object is being referred to by the use of a demonstrative? I will sketch the answer I propose in this paragraph and then fill it out in the body of this section. We can distinguish between the functional role of a concrete object and the categorical basis of that functional role. That is, we can distinguish between (1) the range of effects provided when various inputs are given to a situation involving the concrete object—characterizing these is characterizing the functional role of the object—and (2) the categorical object itself, whose presence in the situation explains why these effects are yielded in the presence of the specified inputs. The reason why experience of the object can provide knowledge of the reference of a demonstrative is, I will argue, that it is experience of the object that provides you with your conception of the categorical object itself. It may be a helpful exercise to begin by commenting briefly on the distinction between the functional role of a property and the categorical property itself, the property which has that functional role. If an object has

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a particular shape, for instance, then in virtue of having that shape the object is in a complex dispositional state. Shape combines with the other characteristics of the object to yield the behaviour of the object. So, for example, a round thing will roll, but only if it is made of a rigid material, of a sufficient density, and suitably propelled. A full characterization of the functional role of roundness would of course be quite complicated, but you can see in principle how it would go. We could simultaneously give functionalist characterizations of other characteristics of concrete objects, such as rigidity and density. Yet we would not ordinarily think of shape properties as exhaustively characterized by their functional descriptions. We would ordinarily regard shape properties as the paradigmatic categorical properties of objects. Roundness is the reason why the thing tends to roll if suitably propelled and so on; it is the intrinsic ground of the complex functional state described. Why does it seem so evident to us that we have this conception of shape as a categorical property of the object? I think that the reason it seems so evident is that we take experience of shape properties to be confronting us with the categorical properties that underlie the object's tendencies to various behaviours. Experience of shape properties is what explains knowledge of what the shape property is. It is experience of the shape that confronts us with the categorical property, and thereby explains our grasp of the concept of shape as categorical. If this is right, then perceptual experience has a theoretical role to play. Experience of the world is what explains our grasp of the concepts of observable properties. So for any description of the phenomenal character of experience of shapes, we can ask whether phenomenal character, so described, could be what explains our grasp of the concepts of the categorical properties of objects around us. For example, an analysis on which experience of shapes is a matter of having sensations of a particular sort would evidently fail us at this point. All that having sensations would do is to provide you with knowledge of yet another of the dispositional characteristics of roundness: that round objects tend to produce this kind of visual sensation when seen in suitable light. Merely having the sensation could not explain how it is that you have the conception of the categorical property of roundness. I want to propose that there is similarly a sense in which experience of the object confronts you with the identity of the categorical thing itself. Let me explain what I mean by this, by setting out why we need the notion of the identity of a macroscopic object. What can we causally explain by appealing to the identity of a macroscopic thing? I think that there are two types of phenomenon we use the notion of 'this particular object' in explaining. First, objects have tendencies to propagate causal influence over time. We could say:

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Suppose the object would, in the absence of interactions with other objects, remain uniform with regard to characteristic Q over a period of time. Then a mark—a modification of Q into Q'—is transmitted over the period if the object has Q' at all points throughout the period without additional interventions. (Salmon 1984:148)

And we can say that an object at a later time is capable of bearing marks transmitted by the way it was earlier. This is a doubly counterfactual formulation: whether we have a case of mark transmission depends on how things would have gone had it not been for the original marking interaction. And the later object has the potential for mark transmission from the earlier object. It doesn't matter if there actually are any marking interactions; what matters is what would have happened if there had been any. In the case of an ordinary physical object, we would usually suppose that these counterfactuals are not barely true; that sameness of the object over time is what explains this internal causal connectedness. Suppose that while at school you carve your initials on a desk. When you revisit years later, there they still are. In this case, the identity of the object over time seems to be the categorical ground of its potentiality to sustain this kind of marking interaction. The reason why the marks are there is that it's the same desk. If this is right, then sameness of an ordinary object over time is what causally explains the potential of the object for mark transmission over time. We need the notion of a categorical object, whose categorical identity can be the ground of its complex of dispositions to interact with other objects. The second type of phenomenon in explaining which we use the identity of macroscopic objects has to do with the tendency of macroscopic objects to produce ranges of correlated effects. For example, one person addressing a group of people may produce a range of effects in them: there may be a shared sense of lassitude, or on the other hand intense intellectual excitement, after such an encounter. What explains the correlation in the effects produced is, in part, that it was one and the same person addressing all these people. These explanations, of mark transmission over time, or of correlated effects at a time, by appeal to the identity of a macroscopic object, are in a sense independent: that is, they are not merely promissory notes for some more fundamental microphysical explanation. They are complete as they stand. Hilary Putnam (1975) remarked long ago that when we explain the inability of a square peg to get through a round hole by appealing to the rigidity of the materials used and the fact that the cross-section of the peg is greater than the diameter of the hole, this explanation is complete as it stands; it is not merely a promissory note to be redeemed by an excursion

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into microphysics. Similarly, grasp of the categorical identity of the object enables you to give high-level explanations of mark transmission and the presence of correlated effects which are complete as they stand, and do not depend upon the possibility of their being deepened by shifting to a microphysical level. Someone might propose a functionalist account of the identities of objects; that is, you might propose that we can regard ordinary mediumsized concrete objects as being exhaustively described by their functional characterizations. It seems unlikely, though, that we will in fact be able to formulate the required functional characterization of physical objects in such a way as to reflect accurately the ways in which we ordinarily think about physical objects. On this approach, we have to try to reflect all the distinctions we make about sameness and difference of object in terms of the functional characterization alone. So, for example, we have to say that what makes it true that this tree now is the same as the tree I observed yesterday, is, for instance, the possibility of this tree bearing marks transmitted by the earlier tree—that if I carved my initials on the tree yesterday there they will be on the tree today. However, if we are not allowed to take the identity of the object as given in determining which marks are being transmitted, then we may find that all kinds of cases count as mark transmission in which we do not have identity of object. For example, if a forger copies a painting, then the marks on the forgery are there because of the markings of the original; but that does not make the forgery into the original painting. Or again, we can imagine that some objects might lose their marks easily; when you mark them they simply reset themselves to their initial condition. In general, we would ordinarily think of these functional considerations about the relations between earlier and later objects as providing evidence for sameness or difference of object, rather than as actually constituting sameness or difference of object. We would think that sameness or difference of object is a categorical fact. We would think that sameness of object is the reason for the correctness of various counterfactuals, such as the counterfactuals relating to mark transmission. Seeing my initials carved on the tree is evidence for thinking that it is one and the same categorical object again. But on the functionalist approach to physical objects that we are considering, there is no way of explaining how we could have formed such a conception of the physical object as categorical; physical objects have the status merely of posits invoked to explain experience. How is it that we have this conception of the identity of a macroscopic object, as the categorical ground of these dispositions to mark transmission over time and for 'common cause' functioning? I am arguing that it is experience of objects that provides us with our knowledge of them as

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categorical. It is experience of objects that provides us with our knowledge of the object as the basis of the potentials for mark transmission and for functioning as a common cause of correlated phenomena. This is why experience of the object is the canonical way in which we have knowledge of the reference of a demonstrative term. When we experience an object we do not perceive it simply as a collection of potentialities for mark transmission over time, and so on; we think that we are confronted with the categorical ground of the potentiality for mark transmission over time. We think that what we experience is the reason why there is this capacity for mark transmission. We ordinarily take it that experience provides us with our conception of the categorical properties and objects in our surroundings, and this is the reason why experience of the world seems to be used in our grasp of demonstratives. 1 can bring out the main point in one further way, by looking at a connection between the analysis of blindsight and Gibson's (1979) notion of an affordance. Suppose you had a blindsighted subject who lacked awareness of the contents of his blind field, but had a great deal of visual information about them and could act on the objects in his blind field just as rapidly and accurately as an ordinary subject. What would this subject be missing? Suppose this subject has an object in his blind field, say, a lamp. Why should we not say that this subject is in a position to understand the demonstrative, 'that lamp'? Of course, the subject can formulate descriptions such as 'whatever is in my blind field' that might uniquely identify the thing. But why should we not say that the subject can interpret the demonstrative 'that lamp' in just the way that we ordinarily do, without having to form descriptions singling out the thing? When we ordinarily make reference to an object we can see, experience of the object seems itself to provide us with knowledge of which thing we are talking about, without there being any need to formulate descriptions applying to it. Why shouldn't the visual information that the blindsighted subject does have about the lamp be capable of sustaining an interpretation of the demonstrative in just the same way? 1 think we can immediately say that the blindsighted subject may grasp many of the potentialities for action provided by the object. That is, if you ask the subject to try to reach for the thing, for example, the subject may well reach in the right direction, with his hand appropriately configured to pick it up. We can even go further, and suppose that the subject could guess which movements to execute to produce light. In Gibson's terms, the blindsighted subject could be said to have information about many of the 'affordances' provided by the object; an 'affordance' being something that the object will provide you with if you act suitably on it. So, for example, a glass of water affords drinking, and a chair affords sitting. An affordance

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is a dispositional characteristic of the thing, a tendency it has to yield a certain result if treated in a particular way. On the analysis of blindsight suggested by Milner and Goodale (1995), this would, I think, be exactly the right way to describe what the blindsight patient has. As we saw in Chapter 3, Milner and Goodale distinguish between an 'action' pathway and a 'perception' pathway in vision. The 'action' pathway is in general remote from consciousness, but holds the information used in the visual control of action. Roughly, much of what Gibson said about affordances seems to apply to the 'action' pathway; the 'action' pathway determines the affordances provided by the object. The 'perception' pathway, in contrast, is what sustains visual experience of the object. In blindsight, according to Milner and Goodale, the primary visual cortex is damaged, so neither the 'action' nor the 'perception' pathway receives input from it. But the 'action' pathway, unlike the 'perception' pathway, does still receive input from several other visual structures. So the blindsighted patient can grasp many of the Gibsonian affordances provided by the object, without yet having conscious visual experience of the thing. Gibson seems to have thought that the affordances provided by an object are all that we ever see. This view is hard to sustain. Once, when I visited Warwick University Psychology Department, someone told me the following story. One year, pigeons started nesting in the concrete interstices of the multi-storey car parks in the university. Presumably, according to my informant, pigeons perceive these Gibsonian affordances directly. These would immediately look like good nesting places. But it had never occurred to humans that it was so. These affordances are not perceived by humans. But it is not as if the matter is entirely opaque to us. For though we cannot perceive the affordances directly, we can see the reasons why these interstices would be good for nesting. We do not see the affordance itself; we see the ground of the affordance. This should be quite puzzling, on Gibson's view. Gibson seems to have thought that ordinary conscious vision, in whatever species, provides knowledge only of the affordances the environment provides for that species. So a cat chasing a bird up a tree, for example, sees only what the tree affords it, the cat; the cat does not see what affordances the tree provides for the bird. If this were right, we should only be able to see that the car parks afford car-parking, and their potential for nesting should be as inscrutable to us as it is to a cat. But that is not how things are. Or again, suppose, for example, that an unfamiliar piece of apparatus appears on a workbench. I have no idea what this thing is for. I don't know if can touch it—maybe I will be electrocuted, or the thing will blind me, if I do that. Or maybe it is simply the latest kind of television, or a paper weight. So I don't see it as affording anything in particular. In that

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case, by Gibson's theory, the thing should be simply invisible; I should be able to see it only when I am told what it is for. But that is not a persuasive conclusion; it seems perfectly obvious that we can see things without knowing what they can be used for. Consider looking at the stars in the night sky. Apparently some people can use them for navigation, but I have to say I would not know where to begin on that-—I have never even been able to identify the constellations. The stars afford me nothing, except maybe aesthetic pleasure; I have no potential for using them in action, I do not know how to begin acting on them. But they are nonetheless visible, despite not affording anything in Gibson's sense. So the view that visual experience is confined to affordances seems hard to sustain. The natural view to oppose to Gibson is that visual experience does not provide us with knowledge of affordances. It provides us with knowledge of the categorical properties of objects which are the reasons why the objects have the affordances they do. This is particularly compelling when you consider shape properties, such as the shapes of the concrete interstices. It surely is plausible that ordinary experience of the shape of an object does not provide you merely with the endless opportunities for various types of action made possible by its having that shape. It confronts you with the categorical shape property itself, the reason why the object provides all those opportunities. A blindsighted subject with an intact visuomotor system plainly does perceive the affordances of the objects around her; she may be able to drink from a glass and eat from a plate. And the affordances may be all that the subject perceives; it may be that Gibson's picture does indeed apply to such a subject. But what is the subject missing? If the subject reaches and grasps successfully, the subject nonetheless does not know why the reaching and grasping has been successful. That is the real reason why such a subject, no matter how fast, accurate, and reliable she may become, is still said to be 'only guessing'. All the subject has is the fact of success in action, without any understanding of why she has been successful. The subject has been right in thinking that there are these affordances there, but does not know why the world has afforded just this and that. If, for a moment, the subject is allowed conscious experience of the blind field, what that conscious experience provides is knowledge of the reason why her actions have been successful; knowledge of the reason why those affordances were there. What the blindsighted subject lacks, and what is provided once there is experience of the object, is perception of the reason why the object affords the various actions that it does. Someone who has conscious experience of the glass and the plate experiences the categorical ground of those affordances; what conscious experience provides is knowledge of the reason why just that reaching and grasping would be successful. If this is correct,

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though, our analysis of what experience is has to acknowledge that experience of the world is what explains our grasp of what the world is intrinsically like. Experience of the object has to explain how it is that we can gasp demonstratives referring to the object as referring to a categorical object, not merely a collection of potentialities. This means that, given any description of the phenomenal character of experience of objects, we can ask whether experience, so described, would be capable of explaining our grasp of a demonstrative referring to the thing. A simple illustration of how this requirement can be violated is again provided by the idea that experience of an object is a matter of having sensations produced by the object. Merely having sensations could explain how it is that you have the conception of the object as a hypothesized cause of those sensations; having sensations could explain how it is that you can identify the object as having a disposition to produce those sensations. But it could not provide you with knowledge of the categorical thing itself, the thing which is causing those sensations. But that is exactly what happens when you rely on your experience of the object to interpret a demonstrative referring to that object. So the picture of experience as the having of sensations once again does not seem to be tenable. These points put significant weight on our conception of what it is to experience an object. If experience of the object is to be what explains our grasp of the object as categorical, then we cannot think of experience of the object as consisting merely of grasp of a demonstrative thought about the object; it has to be what explains our capacity for demonstrative thought about the thing. So experience of the object should not be regarded as consisting in grasping a thought about the object, 'in the mode: vision', as we might say. Rather, consciousness of the object has to be a more primitive state than thought about the object, which makes thought about the object possible by revealing the object to you. I will argue that we have to think of experience of the object as a primitively relational state, with the object itself figuring as a constituent of the experience. We have to regard experience of the object as reaching all the way to the object itself, and thereby providing us with the conception of that categorical object.

4. Representationalism It seems to me, then, that the need to acknowledge what I earlier called the Intrinsicness Condition, that experience is experience of the categorical, argues in favour of what, in the last chapter, I called a Relational View of experience, on which the qualitative character of a visual experience is

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constituted by the objects and properties viewed. We can contrast the Relational View with Representationalism (Dretske 1995; Tye 1995). The Representationalist View of experience aims to give a naturalistic account of what it is to experience a property or object. There are two parts to the Representationalist View. There is, first, the idea that all aspects of experiential content are representational. Secondly, there is the idea that we can give a causal analysis of representational content. Representationalism, so described, is a matter of driving further one of the views I discussed in the last chapter, on which the representational content of experience has to be what is responsible for the explanatory role of experience. In giving a causal analysis of representational content, there will be many types of causal relation to which we could appeal. (For some influential types of causal analysis, see Dretske 1981, Fodor 1990, and Millikan 1984. For an overview, see Loewer 1997.) For the moment, though, we can begin with the following formulations, and introduce complications as required. So far as the representation of properties is concerned, the guiding idea is that the prototype of all representation is one state of affairs being causally correlated with another, so that one can serve as a sign of the other. So the idea is that brain states, in particular, can be causally correlated with external states of affairs, in that a brain state may be reliably produced by just one type of external condition, and so serve as a sign that the external condition obtains. Similarly, a brain state may represent a particular object, by being a reliable sign of the presence of that thing. It is a critical point that the causal connection which the causal theory takes to provide experience with its content should be taken to hold between some phenomenon in the world and a brain state, rather than being a matter of the external phenomenon causing the experience itself. Within the context of the Representationalist programme, one reason for this is obvious. If the experience itself were caused by an external phenomenon, and this causation were what provided the experience with representational content, then experience would have to be regarded as possessed of intrinsic, non-representational features. It would be in virtue of bringing about an experience with particular intrinsic, non-representational features that an external phenomenon could be said to be represented by that experience. But then we would have already lost the first of the Representationalist's theses: the thesis that experience is exhausted by its representational content (Dretske 1995: 36-7; also Lycan 1990 and Tye 1991). On the Relational View I discussed in the last chapter, the phenomenal content of the experience of an ordinary observer is constituted by the qualitative character of the view the observer is currently enjoying: which objects and properties are there in the scene, together with the viewpoint from which they are being observed.

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At this point, though, you might wonder whether there is a significant difference between the Relational View and Representationalism. Notice to begin with that whichever view you hold, you have to acknowledge that there are causal conditions on what we can be said to experience. It would not be credible to suppose that we might have experience of objects or properties which are not causally affecting us in any way, and which never have causally affected us in any way. As a first shot at describing the kind of causal connection that is required for there to be experience of an object, we might try the following. When you have experience of an object, that experience will have a certain functional role, and that functional role may be realized by a brain state. For the experience to be experience of an object, that object must have played a role in bringing it about that you are in that brain state. For future reference, let me write this out as the Causal Condition: The Causal Condition: When you have experience of an object, that experience will have a certain functional role, and that functional role may be realized by a brain state. For the experience to be experience of an object, that object must have played a role in bringing it about that you are in that brain state. Someone who takes the Relational View will endorse the Causal Condition; someone who takes a Representationalist View will endorse the Causal Condition. What difference is there between them? The proponent of a Relational View, having acknowledged the Causal Condition on what an experience can be said to be an experience of, can hardly object when the Representationalist attempts to use the Causal Condition to define a notion of 'representation'. Attempts at defining such a notion are in themselves unexceptionable. What is problematic is the further step: to attempt to characterize the explanatory role of experience in terms of this notion of representation. The Representationalist is committed to saying that it is in virtue of its representational content that experience can play its explanatory role. But just how could a representational content of experience explain our knowledge of the reference of a demonstrative? On the face of it, there are just two options here. First, you might suppose that the subject grasps the representational content of her experience, and then uses that understanding of representational content to interpret ordinary demonstratives. This strategy does not seem promising. For we have no account of how the subject is supposed to understand the representational content of experience. Either this content is grasped without the benefit of any further appeal to her experience of the object, in which case we need some explanation of how the explanatory role of experience can be set aside in this case. Alternatively, the subject's grasp of

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the representational content of her experience does have to be explained by appeal to her experience of the object, in which case we are embarked on a regress. There is, therefore, overwhelming pressure on the Representationalist to find a different account of the way in which the representational content of one's experience can explain one's knowledge of the reference of a demonstrative. And the natural move is to appeal to the functional relations between the representational contents of one's experiences, one's other propositional states, such as beliefs and desires, and one's actions. But as we saw in discussing Dennett's functionalism, this approach cannot acknowledge the role of experience of the object in providing knowledge of the reference of a demonstrative. At best, it provides a description of the ways in which one goes about verifying and acting on the basis of demonstrative propositions, rather than a characterization of the knowledge of reference which causes and justifies one's use of particular procedures to verify and to act on the basis of demonstrative propositions. As we saw, the fact that experience of objects can provide a knowledge of reference which will cause and justify the use of particular procedures for verification and action is related to the fact that the phenomenal content of experience meets the Intrinsicness Condition—that experience is experience of the categorical. We can bring out this relation by remarking that the Representationalist might respond to the objection I have just raised by disputing the Intrinsicness Condition. (In Chapter 12, section 4, when I review this argument in a different context, we will see that in fact the Representationalist seems committed to this response; the Representationalist cannot acknowledge the Intrinsicness Condition.) That is, the Representationalist might say that we do not experience categorical, substantial objects; in experience we only ever encounter collections of dispositions. Suppose the Representationalist maintains that there is no more to our experience of an object than experience of it as something whose properties can be verified thus and so, and which can be acted on thus and so. Then there is no question of experience yielding a knowledge of reference which could cause and justify the use of particular procedures for verification and action: the subject's grasp of the representational content of her perception just consists in a tendency to use those procedures for verification and action. Proponents of a causal theory of content have sometimes seemed quite sympathetic to such an approach. If we ask whether it is the dispositional or the categorical that is causing the brain state, then it seems evident that we do not have to choose: the dispositions are present because the categorical objects or properties are present, and each has a role to play in explan-

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ation. But the question for the Representationalist is whether it is the categorical or the dispositional that is being represented by the system. On the face of it, there are two different views you could have of what this kind of causal theory delivers as the representational content of an experience: (1) The experience represents the properties as dispositional and the objects as collections of functional connections. (2) The experience represents the properties and objects as categorical, as the grounds of various complexes of dispositions. These are quite different views. On view (1), experience represents the world only, as it were, up to functional isomorphism. That is, suppose there were an environment which was, from a functional or dispositional point of view, structurally just like our actual environment, including the structure of its impacts on the brain. Suppose, for example, that you are currently watching a game of tennis, so your environment consists of the tennis players and the ball. The simplest way to imagine a functional analogue of this environment is to suppose a brain inside a complicated vat, which has internal structures that correspond to, for example, ordinary tennis balls and tennis rackets, in that the causal impacts that the tennis rackets can make on the ball have their structural analogues in the causal impacts that two types of internal vat-configuration can have on a third type of vat-configuration. And suppose that this parallel in causal structure is actually quite far-reaching, so that all the items that we ordinarily encounter, and the causal relations among them, in so far as they ever affect us, and their causal relations to us, all have their structural analogues in the patterns of causation among internal states of the vat and their causal relations to the brain occupying the vat. Then, according to view (1), our experience does not differentiate between our environment and the environment found in the vat. According to view (1), experience represents the world only up to functional isomorphism, so our experiences do not differentiate between our actual environment and the environment found in the vat. Of course, the causal theory of representation was introduced in connection with Twin Earth cases, in which the locally known functional characteristics of two stuffs—water and XYZ, for example—may be the same. The representations of those in an environment featuring water may nonetheless be different in content to the representations of those in an environment featuring XYZ. But this point still leaves it open that in either case, the stuff being represented is still represented as a complex of powers, some of which may not be known by the subject, rather than being represented as the categorical basis of a collection of powers. The microphysical characteristics of water, or of XYZ, will typically be characterized using

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dispositional notions, such as the notions of particles ultimately defined by the laws governing their behaviour. As I said, the mere existence of a causal condition on representational content will not differentiate between view (1) and view (2). We can think of the representation as being caused by a disposition just as well as we can think of it as being caused by the categorical. All we have, to differentiate between view (1) and view (2), is what the subject makes of the representation. Does the subject interpret the representation as relating to the dispositional or as relating to the categorical? All that we have to appeal to, as constituting the subject's interpretation of the representation in one way or another, is the pattern of functional relations in which the representation stands to other representations and ultimately the actions of the subject. But it is very hard to see how the existence of such a pattern of functional connections could constitute the subject's interpreting the representation as relating to the categorical, rather than the dispositional, characteristics of the external stimuli. For the pattern of functional connections is determined only by the dispositional characteristics of the external stimuli. If you varied the intrinsic nature of the objects around the subject, but kept their dispositional characteristics constant, the very same pattern of functional connections would still be appropriate for the use of the subject's perceptual representations. And the actions of the subject would also be of the same type, in responding to and manipulating the affordances of the external stimuli. So on a Representationalist view, we seem to have no motive for going beyond view (1), to suppose that the subject is representing the categorical. On one reading, Hilary Putnam's famous 'Proof (Putnam 1981) that we can't all be brains in a vat depends on just this 'dispositional' interpretation of the causal theory of content. Sceptical worries are often formulated as questions about my right to take it that my perceptions are caused in the way I think they are. Perhaps, the sceptic says, my perceptions are caused in some quite different way: by the machinations of a malevolent demon or the operation of the vat-tending machinery. The sceptic's idea is that the qualitative content of my experience could be as it is, however the experiences were being caused. Putnam's point, in opposition to this kind of scepticism, is that the way in which my perceptions are caused will affect the contents of my thoughts. And however my perceptions are caused, the contents of my thoughts will be correlatively affected in such a way that they come out true. So I will always be right when I say, 'I am not a brain in a vat'. That, in a nutshell, is the Proof. On the reading I am proposing, Putnam's idea here is that the vattending machinery will be functionally isomorphic to the everyday world. On this interpretation, the point is that on a causal theory of represen-

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tation, the world is represented only up to functional isomorphism. So if we consider a brain in a vat, its representational system may still be stating truths about its functionally defined environment. In support of this, you might argue that it is hard to see how brain states could be causally sensitive to anything more than the dispositional. For if we held the dispositional constant, but varied the categorical, the brain would still respond in the very same way. So how could you justify saying that the brain state is sensitive to anything other than the dispositional? We might say that this argument is an argument for the 'dispositional interpretation' of a causal theory of content. (Of course the argument is not conclusive, since the categorical objects and properties are playing a role in the causation of our states, just because they underlie the dispositional properties; but the causal theory of content itself is unlikely to provide the rationale for resistance.) The reason Putnam's Proof is intuitively so unsatisfactory is that we ordinarily take experience to provide us with knowledge of far more than merely the functional structure of the medium-sized world. We take ourselves to have knowledge of the categorical objects and properties around us. We ordinarily think we know what the world is like. If the world is that way, it is not a bit like a vat. So if you are told that were you to be in a vat, all your thought-tokens would be systematically reinterpreted so that they came out true, this is not likely to seem reassuring enough. The world would still not be the way you think it is. From this perspective, Putnam's Proof is not reassuring. It only emphasizes the conclusion that, on the dispositional interpretation of a causal theory of content, we have no conception at all of what the world is like. Wildly different scenarios, on which perceptions have massively different external causes, are all quite consistent with having a representational system within which you accept only truths. I can put the point like this. Consider the various scenarios in which the contents grasped by the brain all, on Putnam's account, express truths: the case in which the brain is hosted by an ordinary human being going about ordinary business, the case in which vat-tending machinery for that brain is all that there is, and the case in which there are endlessly many different brains all plugged into a single central vat. In each of these cases, there are different categorical properties and objects in the environment of the brain. What is in common between these cases is only this: that the environment of the brain has sufficient functional structure to support the use of language by the brain. All that the brain's use of language guarantees is that the world has that minimum of functional structure. On the dispositional interpretation of a causal analysis of content, that is all that your representational content can be informing you about: the functional structure of your environment. That

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is why we have the guarantee that your representations will generally come out true, because in each of the alternative scenarios, the world does have that functional structure. But what you would have commonsensically hoped for is some intimation that the world is the way you think it is. And you do not get that reassurance by being told that one way or another, your representational system is expressing truths. That is the intuitive reservation about Putnam's Proof. When you think it through, it is actually a reservation about the dispositional interpretation of a causal theory of content, precisely because the dispositional interpretation gives no role to consciousness in providing us with our conception of what the world is intrinsically like. We can accept Putnam's Proof only if we accept that we have no conception of what the world is like, only a set of representations which one way or another will be interpreted so as to come out true, whichever way the world is. On a Relational View, in contrast, we have to appeal to the ideas of categorical properties and categorical objects in characterizing the content of experience. And I think it is instructive here to contrast Putnam's Proof with the Relationalist response to the sceptic. The sceptic's idea is that the qualitative character of a subject's experience could be as it is whether the subject was in a world of trees and oceans, or in a vat. If the qualitative character of the experience was the same, whichever scenario—the trees and oceans, or the vat—was realized, then it is hard to see how the qualitative character of experience could be providing knowledge of intrinsic objects and their characteristics. The categorical properties of trees and oceans are quite different to the categorical properties of a vat—even if there is some sense in which the two are functionally isomorphic. So it is hard to see how subjectively indistinguishable conscious experiences could be providing knowledge of both ranges of categorical properties, in the two scenarios envisaged. There seem to be just three possibilities. One is that neither the experiences of the ordinary subject nor the experiences of the vat subject provide knowledge of categorical objects and properties; rather, in the first instance, all that the experiences provide is knowledge of the types of sensation that the objects and properties tend to produce. As we have seen, this view cannot acknowledge the explanatory role of experience. The two remaining possibilities are both consistent with the Relational View. The second option is that you might argue that the experiences of the ordinary subject and the experiences of the vat subject would after all be qualitatively different, because of the differences in the qualitative characters of their surroundings, and that both sets of experiences could provide knowledge of categorical objects and their properties. Finally, it may be that the experiences of the ordinary subject and the experiences of the vat subject are again qualitatively different, but that the experiences of

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the ordinary subject do provide knowledge of categorical objects and their properties, whereas the experiences of the vat subject have to be regarded as hallucinations produced by the activity of the vat machinery, which cannot provide knowledge of any categorical objects or properties. On the Relational View, the phenomenal character of experience is thought to depend not just on the intrinsic states of the relevant brain, but on which objects and properties there are in its surroundings. So a human subject and a brain in a vat would, on this view, have qualitatively different experiences, because there are different categorical objects and properties in their surroundings. The point here is emphatically not that brains in different surroundings will be acted on differently by different objects, so that they come to be in different intrinsic states, and consequently sustain different types of conscious experience. The position, on the Relational View, is rather that even though the brains are in the very same intrinsic states, they are sustaining different types of conscious experience, in virtue of the fact that there are different things in their surroundings. This difference in conscious state is not to be thought of as a matter of the states being given some 'high-level' description in terms of the objects in their surroundings, with there being a 'lower-level' description of them as intrinsic conscious experiences on which they are qualitatively the same. The position is rather, on the Relational View, that at the most basic level of description of the conscious experience, at which we are simply trying to say what the content is of the two types of experience, the experiences are qualitatively different, simply in virtue of the fact that there are different objects and properties in the environment. 5. Traditional Empiricism on the Explanatory Role of Experience I think it is illuminating here to look at the parallels and contrasts between the views we have been discussing and Locke's characterization of the phenomenal content of experience. For Locke certainly aims to acknowledge the explanatory role of experience. On his view, we grasp the concepts of material objects and properties because we have experience of those objects and properties. But how does Locke characterize the phenomenal content of experience? Locke holds a causal theory of the representational content of experience. On his view, simple ideas of perception are signs of their usual causes, whatever they are. We have the simple ideas we do, just because they serve as reliable signs of external phenomena. It is not, he thinks, that we generally reflect on the matter particularly; so it is not that we ordinarily explicitly think of external phenomena as powers to produce experiences

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in us. Rather, we simply use the simple ideas of perception in making our ways through the world. But in fact we are using those simple ideas as signs of their regular causes. So he is ascribing a representational content to those ideas, and giving a causal analysis of how it is that they have that content. Consider a sceptical hypothesis, such as the hypothesis that my experiences of redness are not caused by redness but by something else, or the proposition that my experiences of squareness are not caused by squareness but by something else. Locke's answer to this is that simple ideas 'conform to their archetypes', are 'real', 'adequate', or 'true' (1975: IV. iv. 4; II. xxx. 2; II. xxxi. 2; II. xxxii. 14). His point is that since, on his view, the simple idea is merely a sign only of its regular cause, whatever that is, and the word given meaning by its association with that idea therefore stands only for the regular cause of that idea, whatever it is, the sceptical hypothesis amounts to the hypothesis that the regular cause of a simple idea is not what the idea signifies; but whatever the regular cause of an idea is, that just is what the idea signifies. Here is Locke putting the case: simple Ideas, which since the Mind, as has been shewed, can by no means make to it self, must necessarily be the product of Things operating on the Mind in a natural way, and producing therein those Perceptions which by the Wisdom and Will of our Maker they are ordained and adapted to. From whence it follows, that simple Ideas are not fictions of our Fancies, but the natural and regular production of Things without us, really operating upon us; and so carry with them all the conformity which is intended; or which our state requires; For they represent to us Things under those appearances which they are fitted to produce in us; whereby we are enabled to distinguish the sorts of particular Substances, to discern the states they are in, and so to take them for our Necessities, and apply them to our Uses. Thus the Idea of Whiteness, or Bitterness, as it is in the Mind, exactly answering that Power which is in any Body to produce it there, has all the real conformity it can, or ought to have, with Things without us. (1975: IV. iv. 4)

I should emphasize that Locke's point here is about simple ideas generally; the last sentence of the quotation applies to all simple ideas of perception, not just to ideas of secondary qualities. If we put the upshot of this discussion in contemporary terms, and ask, 'How do I know that I am not a brain in a vat?', where the point of the question is that if I were a brain in a vat, the regular causes of my perceptions would be other than I take them to be, the answer is that my words just do stand for the regular causes of my perceptions, whatever they are. So it is a priori that I am not a brain in a vat. Locke's view thus seems to share with Putnam the dispositional interpretation of a causal theory of content, and his argument at this point seems to be a form of Putnam's Proof that we can't all be brains in a vat, which I discussed in the last section. Locke, however, does not believe that we have no conception of what the

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world is intrinsically like; he thinks that we do have the conception of categorical objects and their properties. But his causal theory of perceptual representation cannot explain how we have this conception, so he introduces a further dimension to his account of phenomenal content. In introducing this further dimension, Locke exploits the fact that on his view, the causation on which perceptual representation is held to depend does not hold between the external phenomenon and a brain state, as it did with the views we discussed in the last section. Rather, on Locke's view, the relevant causal relation holds between the external phenomenon and the perceptual experience itself. Consequently, the perceptual experience itself must be held to have intrinsic, non-representational characteristics. Experiences are signs of external phenomena in virtue of the fact that particular intrinsic experiential characteristics function as reliable signs of particular external phenomena. The simple ideas of perception are reliable signs of their causes in something like the way in which smoke is a sign of fire. The problem Locke is facing is that although my ideas are signs of their causes, I do not yet know what any of those causes are like. If all I ever get is smoke, how do I know what fire is like? In the last section, I was in effect arguing that some version of this problem will in the end face any version of a causal correlation view of content, even one that takes the causal relation to hold between external phenomena and brain states. How can effects provide you, the subject, with any conception of what their causes are like? But since Locke thinks that experiences themselves have intrinsic, nonrepresentational characteristics, he makes a move that is not open to the Representationalist. The move Locke makes is to appeal to his notion of 'resemblance'. Some ideas, the ideas of primary qualities, intrinsically resemble their causes. Those ideas do show what their causes are like. Ideas of secondary qualities, on the other hand, do not resemble their causes. They represent the world perfectly accurately, but they do not show you what the world is intrinsically like (1975: II. xxxii. 15; cf. II. viii. 15). Now Locke's notion of resemblance is generally mocked. One possibility is that 'resembles' should be interpreted in representational terms—the world is the way represented—with the notion of representation still being interpreted in terms of the causal theory. And then we have made no progress towards understanding how experience can explain the subject's grasp of categorical properties and objects. Alternatively, 'resemblance' requires that the intrinsic properties of the experience should be like the categorical properties of the object. The idea is that experience can play its explanatory role by being within the thinker's subjective life, yet possessed of intrinsic characteristics which are just like the categorical properties and objects of which the thinker has to form an understanding.

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It is this second reading of Locke that is the crucial one, at this point in the dialectic. But within Locke's own framework, the move seems untenable. The intrinsic characteristics of experience have to play a double role: they have to be caused by the material objects and properties, and they have to be intrinsically like them. But it is hard to see how there could be anything which played both roles. Whatever it is that the material objects and properties are causing, it is hard to see how it could be something which is intrinsically like those objects and properties. We seem to be faced with the idea of an absurd duplication of the material world in some other area. It is because of this that Locke's notion of resemblance is usually mocked, and because of this that Berkeley's retort, that an idea can be like nothing but another idea, seems perfectly just. Suppose, however, that we drop the notion that the intrinsic characteristics of experience are caused by the categorical objects and properties being seen. Suppose instead we think of the intrinsic characteristics of experience as constituted by the categorical objects and properties being seen. We can characterize the phenomenal content of experience only by saying which 'view' the subject is enjoying. Then we are indeed in a position to understand how the phenomenal content of experience can explain our grasp of what the world is intrinsically like. On this picture—on the Relational View—you simply cannot ask the question that is so pressing for a Representationalist, namely: 'How is the subject representing what she sees?' The reason the question is so pressing for the Representationalist is that, as we saw in the last section, all that there is for the Representationalist to appeal to in answering that question is the use that the subject makes of the representation, and that cannot of itself constitute a grasp of anything more than the dispositional. On the Relational View, in contrast, it makes no sense to ask how the subject is representing what she sees. You can ask from which position the subject is viewing the scene, and you can ask whether the subject is an ordinary observer or if there are idiosyncratic factors affecting the nature of her experience. But seeing the categorical object is not a matter of consciously representing it, so there is no question to be asked about the nature of the representation. Rather, we can think of conscious attention to the object as being itself the categorical ground of the subject's dispositions to use particular procedures in verifying, or in acting on the basis of, demonstrative propositions about the object. And this conscious attention to the object is no more exhausted by the dispositions it grounds than the categorical ever is, in general, exhausted by the dispositions it grounds.

8 Joint Attention In this chapter and the next, I want to set out some extensions of the approach developed so far. They really are extensions of the approach: they are not implications of what I have so far said, or foundations for it. But having provided an analysis of an individual's understanding of presently used perceptual demonstratives, it seems reasonable to ask how this approach might be developed to apply to the various distinctions we might draw relating to an understanding of someone else's use of a perceptual demonstrative, and currently used demonstratives referring to remembered objects. I begin, in this chapter, with the role of joint attention in an understanding of someone else's use of a demonstrative. 1. Understanding Someone Else's Perceptual Demonstratives My topic in this chapter is, then, once again, the way in which we understand perceptual demonstratives: terms like 'that mountain' or 'that book', used to refer to currently perceived objects. We use these terms in expressing perceptual-demonstrative beliefs and intentions, as when I say, 'I'm going to climb that mountain', or 'I've just found a mistake in that book'. I want, in particular, to focus on the way in which I understand someone else's uses of demonstrative terms. That is, I want to focus on the characterization of my knowledge of someone else's demonstrative beliefs and intentions. It has for some time been recognized that demonstrative propositions have a pivotal place in our ordinary thinking. By observing objects, we get knowledge first of demonstrative propositions concerning those objects; observation is in the first place a way of verifying demonstrative propositions. And if you are to act intentionally on an object, by reaching for it or grasping it, for example, then usually you need to have and use a demonstrative way of identifying that object. If I want to pick up the box that contains the money, for example, I can do it only when I know the demonstrative identity, 'That box is the one with the money'. Since demonstrative propositions have a pivotal place in our ordinary

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thinking, a knowledge of someone else's demonstrative thoughts will have a pivotal place in an understanding of that person's thinking. Knowledge of the other person's demonstrative thoughts will be essential to an understanding of what the other person is finding out from observation, and what actions the other person will perform—which box the person will pick up, for instance. But how are we to characterize our knowledge of someone else's demonstrative thoughts? One component in an understanding of someone else's demonstrative thoughts will be knowledge of the causal roles of those states: what causes a demonstrative belief or intention, for example, and which other states or actions it can cause. It is only because you know the causal roles of the other person's demonstrative thoughts that you can use this knowledge in explaining and predicting their actions, for example. So how do you have knowledge of the causal roles of someone else's demonstrative thoughts? For the theory theory, grasp of the causal role of psychological property is a matter of having tacit, knowledge of a theory articulating the causal role of the property (cf. e.g. Stich and Nichols 1995). For the simulation theory, grasp of the causal role of a psychological state is owed to a capacity that you have to simulate possession of that state (cf. e.g. Gordon 1995). You can, in pretence or play or imagination, take on psychological states which are not your own, and in imagination follow through on the consequences of being in that state. This thinking is 'offline' in that its upshot is not permanent, and it is decoupled from action. It provides you with a grasp of causal structure which puts to work the fact that your own states have a particular causal structure, rather than any representation of that causal structure. There is pressure on the theory theorist to weaken the notion of 'tacit knowledge of a theory' so that it becomes difficult to distinguish his view from the simulation theory. Suppose we consider the question whether someone is representing the following aspect of causal role: a belief that if p, then q, and a desire that q, will result in a desire to bring about p. Suppose that on various particular occasions our subject is confronted with the question what the causal upshot will be of having a belief that if p, then q, and a desire that q. On these occasions, our subject takes it that the upshot will be a desire to bring about p. What does it take for our subject to have tacit knowledge of the general principle, underlying those particular judgements? One approach is to take it that this is a question about the causal basis of the subject's judgements about the particular cases (Evans 1985b; Davies 1989). The simplest response is to say that the general principle is tacitly known by the subject if there is a single common cause for all of these particular judgements about causal upshot by the subject. The problem with this approach here is this. Suppose the subject himself has a

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tendency to move from a belief that if p, then q, and a desire that q, to a desire to bring about p. And suppose that this tendency of the subject is systematic. That is, there is a single underlying common cause for all the times the subject makes this move in his own thinking. Now suppose that the subject makes judgements about causal role by running simulations. Then whenever he runs a simulation of having a belief that if p, then q, and a desire that q, he concludes that this will cause a desire to bring about p. And by hypothesis, there is a single common cause for him reaching that result on all these occasions. So by our straightforward definition of 'tacit knowledge', this subject, by running simulations, counts as having tacit knowledge of causal role. The issue between the theory theory and the simulation theory has been lost. Nevertheless, I do not want to pause too long over how we are to separate the theory theory and the simulation theory. I want, rather, to point out that there is a further dimension to knowledge of someone else's demonstrative thoughts. There is more to knowledge of someone else's demonstrative thoughts than knowledge of the causal roles of those thoughts. There is, in addition, a normative dimension. Given that someone's demonstrative thought actually has a given causal role, we can always ask whether it ought to have that causal role. We can ask whether these inputs really are enough for it to be right to form such a thought in response, and whether, given that you have such a thought, that really does make it right to draw such conclusions or execute such actions in consequence of having that thought. The theory theory and the simulation theory do not of themselves explain how there can be this normative dimension to your understanding of someone else's demonstrative thoughts, in addition to your knowledge of the causal roles of those thoughts. Of themselves, the theory theory and the simulation theory only offer views about the format in which you have knowledge of the causal roles of someone else's thoughts. I am focusing specifically on the perceptual demonstratives in demonstrative thoughts, so the question particularly concerns the normative aspect of demonstratives. So the question is, how do we know what the right causal role is for a demonstrative to have? How do we know what ought to be demanded of the input to a thought containing the demonstrative? And how do we know what the implications of a thought containing the demonstrative ought to be? The compelling answer is that we know these things by knowing the reference of the demonstrative. It is because you know which object the demonstrative stands for that you are in a position to assess the causal roles of thoughts containing the demonstrative. But when you understand someone else's expression of a demonstrative

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thought, as when they say, 'That dog is on the loose again', how do you know which thing the person is referring to? The natural answer is that you do it by perceiving the thing. But it is not enough that the thing is in your field of view; it might be in your field of view but quite unnoticed by you. You have to single it out visually. You have to attend to it. Understanding someone else's use of a perceptual demonstrative does not, though, demand only that you and the other person should both be attending to the same object. After all, it might be that you happen to be attending to the object anyway; that would not of itself mean that you knew what the other person was referring to. There are some distinctions we need at this point. First, there seems to be an ordinary sense in which I can be said to understand what you are saying and know what you are thinking, even if you are not so much as aware of my presence. Suppose that I am hiding in the bushes as you come out into the moonlight, and as you look around you soliloquize. You use demonstratives in your soliloquy, referring to, for example, 'that star'. There seems to be no reason why I can't understand what you are saying and know what you are thinking; I can see the star myself and I know that it is what you are talking and thinking about. Of course, there is a sense in which your perspective on the star will be a bit different from mine, since you are seeing it from a different position; but I can compensate for that, either by imagining how it would look from your perspective, or by explicit reasoning about what you can see. All this, without you even knowing that I am there. But it is often said that this kind of situation contrasts with ordinary communication, in which there is common knowledge of what is being said. The classical analysis of common knowledge, given by Lewis in Convention (Lewis 1969) is an infinite conjunction: a fact is common knowledge between you and me if we both know it, we both know that we both know it, we both know that we both know that we both know it, and so on. For example, if there is a carafe between us on a table, we may both be attending to the carafe, and we may both know that we are, know that we know that we are, and so on. I want now to look at what the relation might be between joint attention and common knowledge.

2. A Relational View of Joint Attention Joint attention requires an object to which to attend and two or more people to attend to it. In principle there seems to be no limit to the number of people who could be jointly attending to the same object, but for present purposes I will assume we are dealing only with the two-person case. So one canonical form for a report of joint attention is:

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x and y are jointly attending to z. We cannot, though, suppose that this will be the fully analysed form of a report of joint attention. For when a report of the form 'x and y are jointly attending to z' is true, it will be true in virtue, in part, of the individual psychological states of the two participants x and y. So we ought to be able to say just which psychological states of x and y matter here. And no doubt the analysis should impose the same conditions on x as on y; the two participants have to meet the same conditions for them to be jointly attending. I will say that an analysis is 'reductive' if it is possible to say which individualistic states of x matter here, without this already implying that there is joint attention involving x and another. In contrast, an analysis is 'relational' if ascribing the relevant psychological states to x already implies that there is someone with whom x is jointly attending. There is another issue here, which cuts across this contrast between reductive and relational analyses. Suppose that you are sitting on a park bench watching a swan and someone comes to sit beside you. Perhaps there is some rudimentary conversation. So you shift from solitary attention to the swan, through a condition in which both you and your neighbour are coincidentally watching the swan, to full joint attention. The issue is whether this transition should be thought of as affecting the intrinsic nature of your perceptual experience of the swan. On what I will call a 'non-experientialist' view, your perceptual experience is just the same whether you are engaged in solitary attention to the swan or engaged in joint attention to it. What is distinctive of the case in which you and another are jointly attending is that (a) you are monitoring the direction of the other person's attention, and (b) one of the factors controlling the direction of your own attention is the direction of the other person's attention. Any account will have to find some place for these 'monitoring and control' elements in joint attention. The nonexperientialist view holds that these elements are external to the perceptual experience of attention itself. On what I will call an 'experientialist' account, in contrast, there is a shift in the nature of your perceptual experience itself when we shift from solitary attention to joint attention. Within experientialist accounts, we can distinguish between relational and reductive analyses. On a Relational View, joint attention is a primitive phenomenon of consciousness. Just as the object you see can be a constituent of your experience, so too it can be a constituent of your experience that the other person is, with you, jointly attending to the object. This is not to say that in a case of joint attention, the other person will be an object of your attention. On the contrary, it is only the object that you are attending to. It is rather that, when there is

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another person with whom you are jointly attending to the thing, the existence of that other person enters into the individuation of your experience. The other person is there, as co-attender, in the periphery of your experience. On the Relational View of experience I discussed in earlier chapters, the object of which you have experience is not a cause of your experience, because it is actually a constituent of your experience. So, too, in a case of joint attention, on a Relational View, the other person will not be one of the factors bringing about your experience, because the other person will be one of the constituents of your experience. Of course, the object attended to, and the other person with whom you are jointly attending to that object, will enter into your experience in quite different ways. An experientialist account can accept that there are monitoring and control dimensions to joint attention. Joint attention as such surely requires the causal coordination of attention. There are various notions of joint attention we can characterize that have to do with the way in which attention is controlled. The core of all these notions is that you and I are causally coordinating our attention onto the same object. It might be that we achieve attention to the same object through my slavishly attending to whatever you attend to, though you pay no heed to what I am attending to. Or it might happen that 1 attend to whatever I like and you track along behind me. But it can also be that our attention is reciprocally controlled: that you and I each keep track of what the other is attending to, so that we both work to ensure we attend to the same thing. Putting the notion of causally coordinated attention like this may make it sound as though we will have joint attention to an object only in the cases in which the object itself is of no intrinsic interest, so that it would not draw your attention to it of itself; you are each attending to it only because someone else is attending to it. But, of course, there can be more than one causal factor behind your attention to the object; it can be both partly stimulus-driven and partly driven by appreciation of what the other person is attending to. The important point, for the notion of causally coordinated attention, is that what the other person is attending to should be one of the causal factors making you attend to that thing. So far, causal coordination of attention could be a fairly low-level matter, involving only sub-personal mechanisms so that both parties keep focused on the same thing. To fill out the experientialist account, then, we could say that for it to be true that x and y are jointly attending to z, x and y must be coordinating their attention onto z, in that one of the factors sustaining x's attention on z is that y is attending to z, and one of the factors sustaining y's attention on z is that x is attending to z. This coordination of attention may involve the use of sub-personal mechanisms, rather than explicit, personal-level thoughts about the direction of the other person's attention, or explicit

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intentions to attend to whatever the other person is attending to, as on a non-experientialist model. On an experientialist account, what is distinctive of joint attention, at the subjective level, is that the other person enters into your experience. There surely are causal conditions on this happening. We could say: Causal Conditions on Joint Attention: If x and y are jointly attending to z, then x's experience of perceptual attention will have a certain functional role, and that functional role may be realised by a brain state. For x's experience to be an experience of jointly attending, with y, to z, both of the following conditions must be met: (a) z must have played a causal role in bringing it about that x is in that brain state, and (b) the fact of y's continued attention to z must be one of the factors causally sustaining x's continuing to attend to z. On a non-experientialist account, in contrast, the monitoring of the direction of the other person's attention involves personal-level perception and judgement about the other person, and bringing your own attention into line with the other person's involves explicit intention and planning. On a non-experientialist view, though, the experience of attending to the object is intrinsically the same whether it is solitary or joint attention. On the Relational version of the experientialist view, the individual experiential state you are in, when you and another are jointly attending to something, is an experiential state that you could not be in, were it not for the other person attending to the object. The other person enters into your experience as a constituent of it, as co-attender, and the other person could not play that role in your experience except by being co-attender. So when it is true that 'x and y are jointly attending to z', it will on the Relational experiential view be true that x has the experience of jointly attending, with y, to z. And from this ascription of a psychological state to x, it follows that x and y are jointly attending to z. Of course, it can happen that you think you are involved in joint attention when you are not. You and I might start out jointly attending to one of the fish in a pond, but at a certain point, having for a long period taken myself to be jointly attending with you to that fish, I might find that you have silently slipped away, perhaps long ago. In that case, on a Relational View, I did not have kind of experience I took myself to be having. I took it that you were a constituent of my experience, as co-attender to the fish, when in fact you were not. It would also be possible to have a non-relational, or as I earlier called it, reductive version of the experiential view. On this account, when we are describing the psychological states in which x and y must be, individually,

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when x and y are jointly attending to z, we can describe x's states without presupposing that y exists, and we can describe y's states without presupposing that x exists. Of course, in giving a full analysis of what it is for it to be true that 'x and y are jointly attending to z', the reductionist may have to appeal to causal relations between the direction of x's attention and the direction of y's attention. At that point, the analysis will indeed presuppose the existence of both x and y. It remains true that on the reductionist account, the relevant psychological states ascribed to x in the analysis will not themselves presuppose the existence of y, and similarly the psychological states ascribed to y will not of themselves presuppose the existence of x. So those psychological states can be described individually without presupposing that the subject is engaging in joint attention with another. In contrast, as we saw, on a Relational account the other person is a constituent of your experience when you are jointly attending to something, and present in the capacity of co-attender, so on this account a characterization of the individual subject's psychological state does after all presuppose that this individual is engaged in joint attention with another person. Which, if any, of these pictures of joint attention is correct? I think we have to be quite explicit here about why we need the notion of joint attention at all. It is, after all, not needed for knowledge of the reference of someone else's demonstrative. I can understand your soliloquy in the moonlight perfectly well even though you have no idea I am there, so there is no question of us jointly attending to anything, except in the minimal sense that we must both be in fact attending to the same thing in interpreting your use of a demonstrative such as 'that star'. So to determine which picture of joint attention we want, we still have to explain why any such picture is required, since there is a basic understanding of other people's demonstratives that can be achieved without the benefit of joint attention.

3. Coordinated Attack If I am to know which demonstrative thought you are having, there has to be some way in which it is indicated to me which thing you are thinking about. If you are expressing your thought to me, using a demonstrative term, there has to be what Kaplan (1989b) called the demonstration accompanying the demonstrative—a pointing gesture, some descriptions indicating where to look, maybe a sortal term, and so on. Suppose we consider a case in which the demonstration is a little bit unusual. Suppose that you and I are both sitting in front of the same big screen, but in separate

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compartments, so that we cannot see or hear each other directly, though we can type messages onto the screen. And the screen contains a number of differently coloured circles. You type onto the screen, That circle is the target'. How do I know which circle you are referring to? To let me know which circle you are attending to, you have a set of buttons which will light up lamps in my compartment. To signal that you are attending to the green circle, you push the green button and the green lamp lights up in my compartment. Then I know that you are attending to the green circle. This should not be thought of as a descriptive identification of the object, though, but an attention-orienting demonstration (if you prefer, we might consider an apparatus of electronic arrows which point to the object). The only problem is that the electronic apparatus only functions about 50 per cent of the time; the signal only gets through about 50 per cent of the time. So although I know that you are attending to the green circle, you do not know that I know that, since you do not know whether your message got through. What I need, to let you know that your message got through, is an acknowledgement button, so I can light a lamp in your compartment confirming receipt of your message. Once you get that, you know that I know you are attending to the green circle. But again, the electronic apparatus only works about 50 per cent of the time, so I do not know whether you got my acknowledgement. You have to be able to confirm receipt of my acknowledgement; then I will know that you know I know you are attending to the green circle. And again, the apparatus only works about 50 per cent of the time. And so on. Just to be fully explicit about this, the electronic apparatus never sends an incorrect message; it either works or sends no message at all. And you and I have to interest in sending wrong messages. So any message we get is accurate. Suppose you and I are playing a war game, and we have to coordinate our attack on a single target. If we do manage to agree on the target, then victory is certain, but it will be a disaster if only one of us attacks; anything is better than that scenario. You type up on the screen, 'Let's attack that one at noon', pushing the green button to demonstrate to me which one you mean. The green lamp goes on in my compartment, so I know which one you have in mind. Does this make it rational for me to attack at noon? The problem is that you do not know whether your message has got through. So you do not know whether I will attack, so it is not rational for you to take the chance of attacking alone. So I do not know that you will attack, which makes it irrational for me to attack. I can try to improve the situation by pushing my acknowledgement button, but I will not know whether the message has got through, and you will know that I don't know that, so we will still be sitting tight. And so on; no finite iteration will

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allow us to manage the coordinated attack that is available to us and will secure victory (Rubinstein 1989). The trouble is that we can in practice achieve success in coordinated attacks. If you and I are sitting side by side, not in booths, but in an ordinary situation, it could really be fully apparent to us that we will succeed. But how can we have achieved this? Michael Bacharach sums up the standard response, given by Lewis (1969) and Schiffer (1972), as follows (he is discussing the case in which two people are sitting at a table with a carafe in full view between them): A normal human will not only see the carafe, but will also see the normality of the other co-present normals; lastly, normality has the reflexive property that it is part of being normal to know the perceptual and epistemic capacities of normal people ... These characteristics of normality imply that in the carafe situation an inferential process is set in motion which leads asymptotically, if the agents are logically omniscient, to common knowledge. (Bacharach 1998: 309)

But we have to acknowledge that agents are not usually logically omniscient. Since a rational attack by either or both of us seems to require that we have the infinitary knowledge, it seems to follow that we could never be in a position to attack. You might say that what all this shows is that it would not, in an ordinary situation, without the booths, ever be rational for you and me to launch a coordinated attack on the basis of one of us saying, 'Let's attack that one!'. Perhaps at best there is a thought, 'Well, we'll have to do something sooner or later', that might drive you to take the risk. But this really would be irrational, since we are considering a case in which there are known to be no time-limits on effective action, and the pay-off structure is that mismanaged attack means disaster while a successful attack yields only a significant but limited reward. The trouble is that it seems perfectly evident that even with that pay-off structure in place, in the ordinary case, without the booths, a coordinated attack on the basis of the demonstrative utterance, 'Let's attack that one!', could be quite rational. Intuitively, in an ordinary case, with you and me looking at the screen and no booths, everything is out in the open to such an extent that we can rationally attack. How can that be? This is the puzzle raised by Coordinated Attack. Suppose we go back to considering the ways in which we might analyse the report, 'x and y are jointly attending to z'. Suppose we consider the non-experiential view, on which what this requires of x is that x should be (a) attending to z, and (b) monitoring the direction of y's attention and having the direction of y's attention function as one of the factors causally determining the direction of x's own attention. It seems evident that on this view the puzzle is insoluble. The mere fact that x is attending to z does not

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of itself mean that anything is out in the open. And when we add the monitoring and control conditions to that, it seems evident that x would need, from monitoring y, to achieve infinitary knowledge of what they both know about the direction of their attention to z, by the argument above. Similarly, if we consider the reductive version of an experientialist view, it seems evident that again, on this view, the puzzle of Coordinated Attack will be insoluble. The subject x will still have to achieve infinitary knowledge of their joint attention in order to make the attack rational. It does seem to be different on what I called the Relational version of the experiential view. On this view, what the subject in an ordinary context begins with is experience of the object to which she is attending, with the co-attender present as a constituent of the experience. This kind of relational experience is simply not available to the players in the booths. No matter how many iterations they go through, the end state will never be such a relational state, with the other person figuring as co-attender in one's experience. But on this view, the availability of the relational experience in the ordinary case is what makes it possible for us, in the ordinary case, to be rational in executing a Coordinated Attack. There are two challenges that this view has to face. The first is to check whether being in the relational-experiential state it describes could provide anything more than n-level knowledge of the situation, for some particular finite n. The further challenge is this: suppose we can establish that being in the relational-experiential state transcends n-level knowledge, for any particular n. We need to determine whether that is because the relationalexperiential state merely provides the basis for n-level knowledge, for any finite value of n. That is, if the situation is merely that the logically omniscient subject could derive infinitary knowledge from the relationalexperiential state, then we have not progressed beyond the idea of an appeal to normality set out in the quotation from Bacharach above. I begin with the first challenge, which we can address inductively. Suppose someone claims that being in the relational-experiential state can provide only knowledge of what the other person is attending to; that it can provide only level-1 knowledge. We can see that the significance of the relational-experiential state goes beyond that, by reflecting that if x is in such a state, with y present, as co-attender, as a constituent of the state, then it follows that y too must be in such a relational-experiential state. So y has the experience of attending to z, jointly with x, and on that basis y can know that x is attending to z. And x knows that y has such an experience. So x is in a position to have the level-2 knowledge that y knows that x is attending to z. Hence, x's relational-experiential state is not exhausted by its implications for level-1 knowledge. Suppose now that, for some finite n,

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we agree that x has n-level knowledge of the situation. Then on the basis of y's relational experience, y too has n-level knowledge of the situation. And x can know this. So x can achieve n + 1 level knowledge of y's knowledge of the direction of x's attention. The derivational possibilities of the relational-experiential state do not have a finite bound. Now the second challenge comes. Does this show anything more than that the relational-experiential state can serve as the basis on which a logically omniscient subject—perhaps given auxiliary knowledge of the context (that y's experiences do yield y knowledge)—could derive infinitary knowledge? If not, then we have made no progress beyond the appeal to 'normality'. I think that this challenge has not yet been met; to meet it we have to consider just what it means to say that in x's experience, y is 'present as co-attender', that y too is a constituent of the experience. I think that so long as we think of the role y is playing in the experience as something that we have to understand in broadly representational terms, then this challenge really is lethal. For when you think of the experience in representational terms, all that is happening is that y has been introduced as a constituent of x's experience, but we have as yet been told nothing about how the relationship between x and y is being represented within x's experience. And when we ask what relation is being represented, it seems entirely obscure how that relation, whatever it is, could be anything more than the provision of a basis on which n-level finitary knowledge could be derived, for arbitrary n. I think that the problem here is the Representational View of experience, and it is, indeed, just to counter the Representational View that the Relational account takes the co-attender to be a constituent of the experience. Suppose that we consider for a moment the case of ordinary, solitary attention to an object you can see. Suppose that your eye is resting on a scene— say, a garden—and your attention is now on one plant, now on another. What change does it make to your experience when you shift from highlighting one plant to highlighting another? On a Representationalist account, the difference must be a difference in the representational content of your experience. But it seems quite evident that there need be no such difference in representational content. The tree seems no greener than it did before you attended specifically to it, for example. And although in some cases the shift in attention will result in your obtaining more information about just that tree, as we saw that is not definitive of the attentional shift; a covert shift in attention will not typically lead to any enrichment of your representation of the object. The change, when you shift attention from one plant to another, has to do rather with the basis of the functional role of your experience of the object. When you attend specifically to it, you are in a position to harvest knowledge from it, and to act specifically on it.

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Suppose now we consider the case in which another person enters the content of your experience, not now as the object of your attention, but as your co-attender: not as the thing to which you are attending, but as the person with whom you are attending to a specific object. There is again no reason to think that this shift, from solitary attention to having the other person enter your experience as co-attender, should be thought of as a shift in the representational content of your experience. Rather, there is a shift in functional role. If the other person enters your experience as coattender, then you and the other person are now in a position rationally to engage in joint projects with regard to the object, whether Coordinated Attack, joint investigation of the object, or some other project, such as fighting over it or jointly moving it. This is not in itself a representational change; there is no representation of your relation to the other person, and the way in which the other person seems to you to be may be exactly the same as it was before you became involved in the exercise of joint attention. To repeat remarks I made earlier, I am here only saying that attention and joint attention have functional roles; I am not saying that they are exhausted by those functional roles. Rather, attention and joint attention should be regarded as the categorical bases for the kinds of project we can carry out, whether those projects are solitary or joint verification and action. In either case, being in the state confronts one with the rational basis for one's actions. As we saw, this picture does not seem to be available on either the non-experiential or the reductive views of joint attention; only the relational-experiential account can sustain this non-representational analysis. There is an analogy here between the puzzle of Coordinated Attack and Lewis Carroll's famous puzzle of Achilles and the Tortoise (Carroll 1895). Having crossed the line first, Achilles claims to have beaten the tortoise, a claim the tortoise disputes. But, says Achilles, 'If I crossed the line first, then I won; and I did cross the line first'. The tortoise agrees to that, but resists the conclusion that Achilles won. All right', says Achilles, 'but you must agree that if it's the case that if I crossed the line first, then I won, and if it's the case that I crossed the line first, then I did win. Moreover, it is the case that if I crossed the line first, then I won. And it is the case that I crossed the line first.' The tortoise agrees to all that. 'So I won!', says Achilles. But here the tortoise disagrees. Setting up the problem in this way can make it seem that what the tortoise really needs to appreciate the validity of Achilles' inference is some infinitary knowledge; and the puzzle then is how we can rationally engage in inference without having such infinitary knowledge. But this generates the puzzle only by supposing that our appreciation of logical validity must be a matter exhaustively of the

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representation of logical rules. Similarly, the puzzle of Coordinated Attack is generated by supposing that the relations between the two joint attenders x and y must be a matter of how, in experience or thought, they represent their relations to one another. What I am proposing is that, on the contrary, in both cases we have to go beyond these appeals to representational states, and consider the categorical basis of what the subjects can do. Rational transitions do not always have to be underpinned by explicit representations of their rationality. I am, then, proposing that we should think of joint attention as a more primitive phenomenon than common knowledge; but that joint attention can nonetheless have something of the force, in rendering an action rational, of infinitary common knowledge. The suggestion I want to make is that we can view joint attention as a primitive phenomenon of consciousness; just as the object can be a constituent of your experience, so, too, it can be a constituent of your experience that the other person is, with you, attending to the object. What I am suggesting is that joint attention, so conceived, could of itself have the force usually envisaged for infinitary common knowledge in rationalizing action, and that this explains how we can in practice succeed in tasks such as Coordinated Attack, for which no finite level of mutual knowledge is sufficient. You might point out that Coordinated Attack scenarios can arise in many different cases, not just those involving perceptual demonstratives. The classical cases, indeed, would involve commanders on a battlefield, out of earshot of one another, exchanging messages by means of faulty equipment. And the kind of appeal to joint attention that I am proposing would be out of place in such cases. But the puzzle of Coordinated Attack does not arise in such cases either. The puzzle arises only because it seems evident that in the cases involving a perceptual demonstrative, things are in fact sufficiently out in the open that Coordinated Attack could be rational. Then the puzzle is to understand how that could be, in the absence of infinitary knowledge. In the non-perceptual cases, however, it does not seem at all obvious that Coordinated Attack would be rational in the absence of infinitary knowledge. So there is no need to explain how Coordinated Attack might after all be rational in such a case. I have been talking about the bearing of joint attention on our understanding of each other's perceptual demonstratives. It is easy to feel that the causal coordination of attention, which I have emphasized as an element in joint attention, though plainly of practical importance, does not play any role in an account of communication involving demonstratives, because of the following kind of case. Suppose that you and I look out of our windows at a dog barking in the moonlight. We are attending to the same thing, but this does not count as joint attention because we may not

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even be aware of each other's existence. But suppose, as we lean out of our windows, that you and I catch sight of each other. Perhaps you and I have quarrelled, so that the mere fact that you are looking at the dog has not the slightest tendency to dispose me to continue looking at it. The fact that you are looking at the dog may actually dispose me somewhat to look away, but in fact I remain fascinated by the commotion. So it is not that you are causing me to attend to the dog, or that I am causing you to. There is no 'coordination' between us. I would be attending to the thing whether or not you existed. If, as we look out of our windows, you say to me, 'That dog is barking', I will on the face of it have no trouble in interpreting your remark, which thing you are talking about, or what aspect of it you are commenting on, even though there is no coordination of the control of attention. But this case is only one step away from the case in which I hear you soliloquizing while hiding in the bushes. It is not a case in which we have full openness of communication; we are not yet in a position to launch a coordinated attack on the dog. The case of the dog in the moonlight is a much more unusual case than it might at first appear, because it really has to be a case in which there is zero causal coordination of attention. And that is not at all what would usually happen, even in the case of the quarrelling neighbours. Once you have any interest, however slight, in interpreting the other person's remark, there would ordinarily be some moves towards causal coordination by you; and similarly if the other person has any interest in being understood. The case in which the auditor has no interest whatever in whether he is attending to the same thing as his neighbour, and meanwhile the neighbour is speaking without any interest in whether her audience is able to interpret her correctly, is far removed from ordinary communication, and cannot be used to establish that causal coordination is not necessary in ordinary communication. 4. The Role of Consciousness I said that joint attention to the object is needed if you are to communicate openly with someone else, using a perceptual demonstrative. It is striking that joint attention to an object generally involves both parties being conscious of the object. Recall James's definition of attention: 'it is the taking possession by the mind, in clear and vivid form, of one out what seem several simultaneously possible objects or trains of thought. Focalisation, concentration of consciousness are of its essence' (James 1890:403-4). On this common-sense understanding of the notion, attention is a phenomenon of consciousness. It is a modification of the conscious life: your

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experience is different when you attend to one object from when you attend to another object. Joint attention, I am proposing, we should think of as a further special modification of consciousness. Suppose you think about the subject in a blindsight experiment being asked to report on, say, the orientation of an object in the blind field. The experimenter can see the object perfectly well; the experimenter is consciously attending to it. There is also a sense in which the subject is attending to the object, even without being conscious of it. The subject is selectively reporting on the orientation of just that object, and if he reaches for the object or points to it he is selecting information from just that object to set the parameters for his actions. So even though he is not consciously attending to the object, there is a sense in which he is attending to it. There is even some causal coordination between the experimenter and the patient in their directing attention onto that object. Still, just because he is not conscious of the object, there is a way of understanding the experimenter's uses of perceptual demonstratives which is not available to the patient, when the experimenter says, for example, 'Can you point to that light?'. The patient can construct descriptions which he can use to interpret the demonstratives the experimenter uses, descriptions like 'the light at which the experimenter is looking', or 'the light the experimenter wants me to talk about', so it is not as if their meaning is entirely opaque to him. But the ordinary way of understanding someone else's use of a perceptual demonstrative does not require you to construct such a description. Ordinarily, you interpret someone else's use of a perceptual demonstrative just by being conscious of the object yourself. The joint attention we need to interpret each other's perceptual demonstratives in ordinary communication involves conscious attention to the object. I said that the reason we need conscious attention to the object in order to have knowledge of each other's demonstrative thoughts is that conscious attention is what supplies us with grasp of the normative dimension of the thought. It is because there is conscious attention to the object that you can assess the causal role that the other person assigns to the thought. Conscious attention is what supplies your knowledge of the reference of the thought. And it is because you know the reference of the thought that you can assess the evidence that led the other person to have that thought, and the actions or further reasoning which the other person will be engaged in as a consequence of having that thought. And you have knowledge of the causal role of the thought as a result of either your capacity to simulate the other person, or your having tacit knowledge of a theory about the causal roles that such thoughts have. There is no particular reason to think that your knowledge of the causal role of someone else's demonstrative thought is itself conscious. It is true

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that simulation is often thought of as a way of generating verbal reports or conscious expectations about how someone will behave or how they may have come to their current condition. But this need not be the main or most primitive use of the capacity for simulation. In a recent paper, John Greenwood suggests that 'the characteristic output of simulation may be non-verbal (and perhaps non-conscious) anticipation (or expectation) of behaviour, rather than the verbal prediction of behaviour' (Greenwood 1999:48). The suggestion is that this use of the capacity for simulation, in anticipating and responding to other people, may be what the system evolved to do, and may be more primitive and indeed more accurate than the linkage of the system with our conscious life and capacity for verbal report. Similarly, someone who thinks we have tacit knowledge of a theory of mind need not think that the theory has as its most primitive use the verbal reporting or the generating of conscious beliefs about the causal roles of other people's thoughts. In a general way, we can distinguish between the causal relations that hold among the psychological states of a single person, and the causal relations that hold between the psychological states of different people. Ordinary social interaction involves a grasp of both. Ordinary social interaction requires you to grasp both. Ordinary social interaction requires you to grasp facts about the dynamics of psychological states within a single person, such as the idea that one person's desire that q, and belief that if p, then q, may lead that person to desire that p. And ordinary social interaction requires you to grasp that if two people want an apple, and there is only one apple, that may lead to conflict. The simulation theory and the theory theory, as usually formulated, relate only to grasp of the causal relations among the psychological states of a single person. Simulation will tell you about the dynamics of the psychological states only within the person being simulated, not about the causal relations holding between the psychological states of different people. Similarly, the theory theory, as usually formulated, will say something about the dynamics of the psychological states of a single person, but not about the causal relations between the psychological states of different people. The natural way to develop Greenwood's suggestion is to say that the ability to simulate someone else has its most primitive role as input into the individual's capacity for social interaction: for collaborative activity, resolution of conflict and so on. This does not require that the use of simulation should itself be a conscious activity; it may be use, itself unconscious, of a system which feeds into the practical skills of social interaction. Similarly, tacit knowledge of a theory of mind might be thought to have its most primitive use in helping to guide the practical skills involved

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in social interaction. Of course, it may later be possible to make this knowledge available for conscious report, though we may be fallible in our attempts to make this kind of knowledge explicit. The role of conscious joint attention will be to secure it that we have conscious access to the objectives of our interactive tasks, whether they are collaborative or competitive. This will mean that we have the basic knowledge of objectives which is required if we are to be capable of conscious criticism or assessment of the processes we are using to reach these objectives; knowledge of the processes being provided by simulation or theory.

5. Joint Attention and Other Minds It is sometimes said that joint attention is fundamental to knowledge of other minds. But it is, on the fact of it, hard to see how that could be so. On the one hand, you might begin by operating with a very thin, pared-down notion of 'joint attention', on which it consists merely in an ability for spatial coordination of gaze: that is, that the direction of attention of one individual can be causally affected by the direction of attention of another. In this sense, 'joint attention' is a capacity that is certainly possessed by animals who can follow the direction of one another's gaze. Joint attention in this sense—which is much weaker than any notion I have been considering—seems too impoverished a notion to provide any purchase on the conception of other minds. Michael Tomasello (1995) has argued that there is a richer notion of joint attention than this, and that there are two ways in which it goes beyond this primitive notion. First, joint attention in the full sense requires that both individuals should know that they are attending to the same thing, and that each must know that the other knows this. There must be mutual knowledge that the two parties are attending to the same thing. Second, each individual intends that the other should attend to the thing in question. In effect, Tomasello provides what I earlier called a nonexperientialist account of joint attention. For the moment, suppose we set aside difficulties about the notion of 'mutual knowledge' that Tomasello is working with. The present point is that once we have this rich notion of joint attention, it is not so obvious how it can have any fundamental role to play in our knowledge of other minds. If joint attention requires mutual knowledge (whatever that is) that we are attending to the same thing, it seems to presuppose a great deal in the way of knowledge of other minds; people capable of such mutual knowledge presumably already know a great deal about how other people operate, and are just applying this

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general knowledge to the special case of attention. Again, intending that the other person should attend to the thing in question already presupposes that you are capable of the deliberate manipulation of someone else's attention, which again seems to presuppose more in the way of knowledge of other minds than it can explain. Presumably we would here be dealing with a general capacity for manipulation of one or another aspect of the other person which is simply being applied to the special case of attention here. So again it does not seem that joint attention in this rich sense could be part of the foundation of our knowledge of other minds. So we seem to have a dilemma, oscillating between the thin notion of joint attention as spatial coordination of gaze, which does not seem capable of explaining very much about our knowledge of other minds— certainly animals with no knowledge of other minds at all might be capable of spatial coordination of gaze—and the rich, non-experientialist notion of joint attention, which seems to presuppose quite a rich knowledge of other minds, and does not seem to be capable of explaining how we come by such knowledge. Does the relational-experientialist view of joint attention that I have set out in this chapter offer a way through this dilemma? It seems to me that it does not. Simply saying that the other person may be present, as co-attender, as a constituent of your experience, does not explicitly involve that the subject is exercising knowledge of other minds. But it would be quite implausible to say that such an experience of joint attention could be in some sense the foundation of your knowledge of the psychological states of the other person. Rather, you could not be in the relational-experiential state unless you could grasp that its significance was, among other things, that the other person was also in such a relational-experiential state. So even to be in this kind of experiential state of joint attention presupposes some understanding of other minds. It is worth bearing in mind, however, that there is more to an understanding of psychological states than knowing (a) which states oneself and other people can be in, and (b) the kinds of causal relations that can hold among the psychological states of a single individual, whether oneself or another. There is, in addition, the kind of relation that can hold between the psychological states of different people. Knowledge of this kind of relation cannot be reduced to either (a) or (b) or both. One basic type of such knowledge has to do with what Trevarthen (1979) called 'primary intersubjectivity', which begins with the synchronization of expression by parent and child, the ways in which the expression of one individual can affect the expression of another. But the move to joint attention behaviours opens up a vast range of possibilities for collaboration or

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competition, and a new repertoire of causal relations that can hold among the psychological states of different people. It seems likely that the real importance of joint attention in our grasp of other minds lies in its role here, as an essential factor in one's practical grasp of the causal relations between other people's psychological states and one's own.

9 Memory Demonstratives Having looked at the case of joint attention, I turn now to the second extension of the approach to perceptual demonstratives I have been recommending, to the case of memory demonstratives. 1. Experience of the Past Object Memory demonstratives are made available by memory of events. There are a number of distinctions we can draw among types of event memory. For example, we can distinguish between memory of repeated events— 'that walk we took so often last summer'; memory of extended events— 'that trip to the coast'; and memory of episodic events—'the time you cut your finger'. It is striking that each of these types of event memory may involve conscious imagery, appropriate to the type. I may have an experiential memory of the walk that does not relate to any one occasion, but draws on many; or a series of images which relate to different aspects of the trip, as well as memory of your cry of pain. Each of these types of experiential memory can sustain memory demonstratives referring to objects. I may refer to 'that tree', which was part of the walk, 'that cottage', which figured in the trip, or 'that knife', which divided the flesh. It seems likely that memory is hierarchically organized among the types of event memory. The nesting of an experiential memory in a hierarchy of event memories can provide the temporal and spatial context for the remembered object. If I try to locate 'that knife', with which you cut your finger, I can do it by saying I am remembering the knife as it was while we were out walking during that trip to the coast (Barsalou 1988). Psychologists working on memory distinguish between memory with awareness and memory without awareness, conscious and unconscious memory, or explicit and implicit memory. Straight off, it seems that memory demonstratives depend on conscious memory. In unconscious memory, the past affects the subject without there being any conscious recollection. There is a famous anecdote from Claparede which illustrates the distinction. He shook hands with an amnesic woman, having hidden a

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pin in his hand. The next day she refused to shake hands with him, although she had no conscious recollection of the earlier encounter. She said, 'Sometimes pins are hidden in people's hands' (Kelley and Jacoby 1993). This woman was evidently not in a position to understand a memory demonstrative referring to 'that pin'. The central problem we have to address, in explaining how memory demonstratives work, is to characterize the role that consciousness of the past object plays in knowledge of the reference of the demonstrative. You might suppose that the role of the image is to provide descriptive conditions which must be met by an object for the term to refer to it. The image will provide what we might call pictorial conditions on what the object must be like for the term to refer to it— the sort of object, its colour, size, shape, and so on. The image will not of itself provide any information about the time and place at which the object has to have met these pictorial conditions. The image needs a context, specifying the time and place. The time and place need not be specified using any particular canonical system for specifying times and places. They may be given in terms which relate to one or another memory narrative, locating the time and place with respect to other remembered events and places. Something like this approach, treating the demonstrative as having its reference fixed by a descriptive condition, seems to be the only one possible for demonstratives referring to future objects. Suppose you are in your usual cafe. You have ordered a coffee. All that is sustaining you through the next few minutes is the thought of the arrival of the coffee. You know exactly what it will look like when it comes. You have a vivid image of it. That cup', you say, 'will taste good.' There seems to be no particular reason to deny that this image could sustain a demonstrative referring to the future cup. But it does seem that this could only be by fixing a descriptive condition which an object must meet in order to be that cup. I am not considering a case in which you know which particular cup will be brought to you, and have a memory of it. Rather, since this is your usual cafe, you know in general what the cups look like, so you know what your next one will look like, and you use that knowledge in forming your image. And you have knowledge enough to provide a context for the image—you know roughly when and where the cup will arrive. So you have enough to have a descriptive condition uniquely identifying that cup. And the only way the demonstrative 'that cup' can have a reference is by having as referent whatever cup best fits that descriptive condition. There is an evident contrast here between memory images and images of future objects. Suppose that someone, your sister, say, is trying to remind you of the oddly shaped window in your childhood bedroom. 'It was circular, with spokes running out from the centre, like the wheel of a ship', she says. As she talks, you form a vivid image of the window. The image may be

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correct, detailed, and reliable. Even at this stage, it seems that you could, on the strength of the image, form a demonstrative, 'that window'. Still, you cannot be said to remember the window. It may be, though, that as your sister continues talking, she finally succeeds in jogging your memory, so that eventually you say, 'Aha! Now I remember!' (Ayer 1956: 146). After the shift, your image of the window may be exactly the same as before. There need be no pictorial change in the image. And it may be no more reliable than it was before. But this non-pictorial shift, whatever it is, marks the transition from your merely having an accurate, reliable, conscious image of the past window, to your consciously recollecting it. What differentiates images of past objects from images of future objects is that in the case of future objects, such as my projected cup of coffee, only the first of these two elements is ever available. I can form an accurate, reliable image of my future cup of coffee. But I am irredeemably stuck at that stage, and there is no such thing as my moving to the second stage and saying Aha! Now I have it!' (except in the altogether irrelevant sense in which I might make that remark when the coffee finally arrives). On one analysis, what this shows is that there are two elements in conscious recollection of the past window. One element is having an accurate, reliable, conscious image of the thing. The other element is whatever it is that is gained by the non-pictorial shift. One analysis of the situation is that the second element is an experienced shift in the causation of the image. What difference, if any, does this make to the kind of demonstrative that the image can sustain? On the face of it, you might think it does not make a lot of difference. Of course, since there is now an experienced causal link between the image and the past object, there can be a causal dimension to the way in which reference is fixed. But a causal link was there anyhow in the case in which I form the image in response to the description given by my sister. In that case, there is still a causal link between my image and the past object, although it is one that goes by way of my sister's memory rather than my own. And that causal link is one which is again quite apparent to me. So when, in this case, I use the demonstrative 'that window' to refer to the window of which I have formed an image, there may well be a causal dimension to the way in which the reference of the term is fixed. So there does not yet seem to be a radical difference between the demonstrative I use in this case, and a memory demonstrative. The causal links to the object which serve to fix the references of the two types of demonstrative will be somewhat different in detail. In one case the causal link goes by way of another person, in the memory case it does not. But that difference of detail is all there is to it. You might wonder if there is not a more radical difference between, on the one hand, the case in which the reference of the demonstrative is fixed

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by a purely descriptive condition and the case in which the reference of the demonstrative is fixed by a causal chain which goes by way of another person, and, on the other hand, a memory demonstrative. The first two, it is natural to feel, are only dubiously cases of demonstrative reference at all. With the memory demonstrative we come to a quite different case: here we have a kind of direct connection between the present subject and the past object which means that we have demonstrative reference proper. I think this is a natural reaction. The problem is to explain what the radical difference is, in the case of memory demonstratives. Do we not, in all these cases, just have conscious imagery, which may or may not have one or another kind of causal link to an object? You might respond to this, though, by saying that there is in the case of memory proper more to consciousness of the past object than that. What the 'Aha!' of memory proper signals is not an experience of causation, but a shift from merely having a conscious image to being directly conscious of the past thing itself. To use Russell's term, it signals a shift to being directly acquainted with the past object. It is this kind of direct awareness of an object that alone is capable of supporting demonstrative reference proper. 2. Decentring and the Introduction Rule for a Memory Demonstrative So much, for the moment, for consciousness and knowledge of the reference of a memory demonstrative. Let us consider what an introduction rule for a memory demonstrative might look like (I explained the parallel notion of an introduction rule for a perceptual demonstrative in Chapter 2, section 4). In general, memory exploits broadly logical links between differently tensed statements made at different times. For example, the statement, 'Yesterday it rained', made on Tuesday, is true if and only if the statement, 'Today it is raining', made on Monday, is true. The two statements are truth-value linked. Our ordinary use of memory exploits the existence of these truth-value links. What happens, in our ordinary use of memory, is that you shift from the judgement, 'Today it is raining', made on Monday, to the memory judgement, made on Tuesday, 'Yesterday it rained'. This procedure depends on the existence of logical connections between differently tensed judgements made at different times. We find this exploitation of truth-value links also in our use of memory demonstratives. Suppose you see someone standing in a shop doorway during a downpour and you think, "That man is drenched'. The following day, remembering the scene, you think, That man was drenched'. This is a memory demonstrative judgement, and in making it you exploit its being

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truth-value linked to the earlier demonstrative judgement. The truth-value link here is between a present judgement such as 'That (remembered) man was drenched', and a past present-tensed judgement such as That (perceived) man is drenched'. In this case, even to articulate the truth-value link, we have to be considering the connection between two different types of demonstrative, memory demonstratives and perceptual demonstratives. So the introduction rule for a memory demonstrative will be something like: That (perceived) man is drenched [judged on Monday] That (remembered) man was drenched [judged subsequently] The transitions we make over time, from one tensed judgement to another, are in effect temporally extended inferences. They play a similar role, in our understanding of tense, to the role that introduction and elimination rules play for a logical constant. On a classical realist account, however, we do not simply make these moves: our grasp of the truth-conditions of the propositions involved is what causes us to make these transitions, and it justifies us in making these transitions. I am talking here about grasp of the truth-conditions of judgements made at different times. So what is involved is what I will call 'temporal decentring'. By temporal decentring I will mean the capacity to understand tensed judgements, or statements, made at times other than the present. We have to separate different types of skill involved in a grasp of tense. We have to distinguish between diachronic aspects of one's grasp of tense, which have to do with how one thinks over time, from synchronic aspects of one's grasp of tense, which have to do with one's ability to think in tensed terms at a particular time. Memory, as I have described it so far, exploiting the truth-value links, has to do with diachronic aspects of grasp of tense. Decentring, on the other hand, is synchronic. It has to do with your capacity, at some one time, to understand tensed statements which may have been made at any of a variety of times. (For a review of the notion of temporal decentring as it figures in the psychological literature, see McCormack and Hoerl 1999.) If, at some moment, you are to understand the logical link between two differently tensed statements made at different times, then you will have to exploit the understanding you have, at that moment, of those two statements made at different times. It is almost a tautology that your understanding of the logical link between statements made at different times will have to exploit your capacity for temporal decentring. How does my knowledge of the reference of the memory demonstrative 'that (remembered) man' play its role in justifying me in making the transition over time, from yesterday's judgement 'That (perceived) man is

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drenched' to today's judgement 'That (remembered) man was drenched'? I think it helps to begin on this by thinking first about my own understanding of a perceptual remark I made yesterday. Suppose, for example, that yesterday I was standing in the doorway writing in my journal as the stranger walked in. And I wrote, 'That man is drenched'. Today, looking at the remark in my journal, how am I to interpret it? How do I, from today's perspective, understand yesterday's perceptual demonstrative? You might say that understanding yesterday's perceptual demonstrative is actually impossible. As I used it yesterday, my use of the term depended on my then current perceptions. But those perceptions are gone forever, and so I have no way now of understanding the demonstrative I used yesterday. If this is correct, then there is no way in which temporal decentring can justify my use of the transition from 'That (perceived) man is F' to 'That (remembered) man was F'. We would find ourselves compelled to make these transitions, but lack any comprehension of why they were correct. A parallel for the situation would be that I find there is a logical connective '*', which I simply do not understand, though I used to understand it and back then I accepted a proposition of the form 'A*B'. Now, I find myself compelled, for no reason I can give, to make the transition from this judgement 'A*B', to the conclusion A. In this case I think we would have no hesitation in saying that my making the transition from the judgement A*B', which I do not understand, to the conclusion A, which I do understand, is not rational, and that the conclusion A cannot be knowledge. But this is exactly parallel to the situation in which yesterday's perceptual demonstrative is no longer comprehensible to me, but I find myself compelled to move from yesterday's judgement to the conclusion, 'That man was drenched'. If yesterday's perceptual demonstrative is no longer comprehensible to me, then the transition is not rational and the conclusion is not knowledge. So if we are to acknowledge the status of memory as a form of knowledge, we have to find some way in which I can now be said to understand yesterday's perceptual demonstrative. The simplest approach is to try to recall my perceptions as I stood in the doorway. But this just is memory imagery. My current understanding of yesterday's perceptual judgement will have to rely on just the same memory imagery as is relied on by my understanding of today's memory-based judgement, 'That (remembered) man was F'. So my knowledge of which thing was in question in yesterday's perceptual judgement automatically grounds my use of the current memory demonstrative. It provides me with a guarantee that it is one and the same thing that is in question both times. At this point, though, you might say the problem has simply been shifted back a stage. Through decentring we have found a connection between my present understanding of yesterday's perceptual judgement, and my

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present understanding of today's memory judgement. And the connection does seem to be enough to validate my making the transition from yesterday's judgement to today's judgement. The problem now, though, is that we seem not to have any connection between the way in which I now understand yesterday's perceptual judgement, on the basis of memory imagery, and the way in which I understood it yesterday, on the basis of perception. You might ask whether there really has to be any such linkage. Could we not say that there is an incommensurability between the ways in which we understand the perceptual judgement at different times, but still insist that we do grasp the justification for our ordinary procedures; that decentring is enough to justify our exploitation of the truth-value links? If we have that, what more is needed? The trouble with this is that the way we actually use memory does seem to demand a commensurability between the way in which we understand a perceptual judgement at the time at which it is made, and the way in which we subsequently understand it. We think that whether the current memory judgement is knowledge depends on whether the earlier perceptual judgement was epistemically sound. In making the earlier judgement and in making the current judgement, you were aiming at truth both times; and your success in the earlier enterprise affects your prospects of success in the later enterprise. But if your ways of understanding the proposition at different times were incommensurable, there would be no way in which the two enterprises could be connected. So, to respect the way in which we do use memory, we have to find a linkage between my current understanding of the memory demonstrative and the way in which I understood it earlier. If memory imagery were one style of representation, and perception another style of representation, with no commensurability between the two, then it would indeed be impossible to find any connection between my current understanding of a past perceptual demonstrative and my past understanding of it. For I would be using incommensurable styles of representation in the two interpretative exercises. Of course, conscious recollection causally depends on past perceptions. But the point we have reached is that there has to be a linkage between the content of my present conscious memory, and the contents of my past perceptions. This linkage has to be what we exploit in the decentring that justifies the use we make of memory demonstratives. 3. Surface vs. Deep Decentring We can draw an analogy between temporal decentring and spatial decentring. Spatial decentring is the ability to grasp the egocentric positions

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of things from someone else's point of view. Let me say something first about the strategies that are available for spatial decentring, and then consider a parallel distinction between strategies for temporal decentring. First, a distinction between two different ways of thinking about egocentric space. The notions 'above', 'below', 'right', 'left', 'in front', and 'behind' are usually called 'egocentric' notions, the idea being that they define positions with respect to the subject: the perceiver and agent is taken to be the origin of the frame of reference, and places are identified by their spatial relations to that subject. But there is a basic distinction that we have to draw here between what I shall call relational and what I shall call monadic egocentric spatial notions. Relational egocentric notions are those that we use when we say, for example, 'He is sitting on my left', 'The chasm yawned before him', 'Look behind you', and so on. These notions specify the person whose right or left, up or down is in question. They are two-place notions: 'x is to y's left', 'x is below y', and so on. Now in stating the spatial content of vision, we do not seem to need these relational notions. We do not need the general conception of something's being to the right or left of an arbitrary subject. Rather, we need the more primitive monadic egocentric terms. These are notions such as 'x is to the right', 'x is below', and so on. An animal could quite well have spatial vision even though it did not have the relational egocentric notions; it could not represent anyone else's left or right, only its own. But it is not even as if its vision makes explicit the spatial relations that things bear to it; it is not always itself an object in its own visual field. Its vision represents things as 'to the right' or 'above'; it does not seem correct to say it represents things as 'to my right' using the relational notion, because of the lack of generality in whose right or left can be represented. And the same seems to be true of ordinary human vision. It represents things as 'to the right' or 'above' using the monadic egocentric notions, rather than the relational terms. I said that spatial decentring is the ability to grasp the egocentric positions of things from someone else's point of view. To decentre, one obvious way to proceed is to use relational egocentric notions. That is what we are doing when we say, 'It's behind you!', and so on. You have the problem of representing what the indexical spatial facts are from a position other than the position you currently occupy. From where you are, the path is ahead and the farm is to the right. But, you might say, using the relational egocentric notions, 'The path is to Sally's left and the farm is ahead of her'. This explicitly represents the place decentred to as Sally's position, and relates the places of various things to her. But there is another possibility. You might decentre using the monadic spatial notions. This is what you would do if you formed an image of the scene from Sally's position. The spatial content of the image is given in monadic spatial terms; that the

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image is from Sally's position is not itself part of the content of the image. You are forming the image as part of the project of grasping the indexical facts from Sally's viewpoint, but that this is the project is not itself part of the content of the image you form. To say that, you have to step back from the formation of the image, and use some other method of representation. So the decentring here involves a two-level construction: at one level there is the imagistic representation of the monadic egocentric facts, and at the other level there is the statement of which position it is that is being decentred to. Why should we bother with this kind of two-level construction? The point of this kind of decentring has to do with our need to use ways of presenting the world that involve a viewpoint only implicitly, where the viewpoint from which the world is being described cannot be made part of the description. These ways of presenting the world include perceptions or imagistic presentations, where which person is having the image is not itself part of the content of the image. So if you are to use these ways of presenting the world to indicate how things stand from viewpoints other than your current one, you will need a two-stage construction. At the first stage you describe which viewpoint is going to be presented, and at the second stage you use the implicitly viewpointed system to describe how the world is from that viewpoint. The two stages cannot be collapsed together, because the implicitly viewpointed system will resist any attempt to make it incorporate an identification of which viewpoint is being described. An understanding of the relational egocentric concepts seems to depend on the ability to engage in decentring involving this kind of twolevel construction. To understand the notion of something's being 'above Sally' or 'below Sally', you need some grasp of up and down as notions relating to orientation in the gravitational field. There is an external physical magnitude which up and down relate to. To understand the notion of something's being 'in front of Sally' or 'behind Sally', you need some grasp of in front and behind as notions relating to bodily asymmetries—that we can see in one direction and that we are better placed to act with respect to what is in front of us than with respect to what is behind. There is no external physical magnitude here, only the bodily asymmetry. So far, then, it seems possible to understand the relational egocentric notions without any appeal to the two-stage construction. The problem comes when we consider 'right' and 'left'. This does not reflect some external physical magnitude, but nor does it relate to some bodily asymmetry. If you are told what constitutes 'up' and 'down', 'in front' and 'behind' for Sally, how are you to go about determination of Sally's right and left? The only thing you can do is use the two-stage process: form the image of how things are from Sally's perspective, using your knowledge of what is up, down, in front, and

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behind for Sally to orient the image, and use your prior grasp of monadic right and left to determine what is to Sally's right and left. So an understanding of the relational egocentric notions seems to be constituted by an ability to use the monadic notions together with the capacity for the twostage decentring process. I shall call the two-stage decentring process 'deep decentring' and contrast it with the decentring process which uses only the relational egocentric terms, which I shall call 'surface decentring'. Let us now look at the temporal case. Suppose you consider a tensed statement made at a time other than the present, such as 'That (perceived) man is drenched'. And suppose that you know the time at which the statement was made, using a time specification from a suitable temporal framework. How are you to use the time specification to interpret the statement? The analogue of using relational egocentric notions would be to use complex tenses; but suppose we just use the simplest approach here in decentring. This is simply to delete the use of the present tense, and replace it with the time-specification. So you might have something like, 'That (perceived) man is drenched at noon on Monday'. Just to try to make it unmistakable what process I have in mind here, notice that this interpretation process loses information. By the time the process is complete, the fact that we were dealing with a tensed sentence at the outset has been lost. So you might try to meet this point by keeping a log of the process, so that you record that you began with a tensed sentence. Notice, though, that if you approach temporal decentring in this way, there seems to be no obvious route by which the link between the present memory demonstrative and the past perceptual judgement, as you understood it then, could be made apparent to you simply by your having an understanding of the memory demonstrative. There is, though, another way in which you might go about the interpretation process in temporal decentring. The process I just described is surface decentring. The process I am about to describe is deep decentring. This is, again, a more complex, two-stage construction. In the first level of the construction, you adopt the hypothesis, or the supposition, or the pretence, that it is now noon on Monday. Then, in the second level, you consider, within the scope of the hypothesis, the sentence, 'That (perceived) man is drenched', as a sentence which is currently being uttered. There is no need for any further interpretation of the sentence. This procedure exploits the fact that in my current use of tense, I do not need knowledge of the time to interpret the tenses I use. I might have lost all track of what the time is, and I still understand perfectly well what my tensed utterances mean. That is why it makes sense to raise such questions as 'What time is it now?', Is it still January?', and so on. That such questions make sense exploits the fact that I do have a current temporal

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location, that these sentences are being uttered at determinate times, but I can understand them without knowing what those times are. In contrast, to understand a use of tense at another time than the present, I do need to know the time of utterance. In this second way of understanding a use of tense at some time other than the present, tense is used, not mentioned, in the final understanding one reaches. One reaches imaginatively to the past time and, within the context of the imaginative project, thinks the tensed thoughts. This way of understanding a past use of tense is deep decentring. You might think of it on analogy with consciously imagining the mental states of another person than yourself; this is imagining the properties of another time than the present. The question I left hanging earlier was the relation between my current understanding of a past perceptual demonstrative and my past understanding of it. This seems to turn on the relation between my current memory imagery and my past perception of the object. But it seems possible to think of the relation like this: that grasp of the memory demonstrative just consists in deep decentring to the past time, the time at which the past perceptual demonstrative was used. We can think of knowledge of the reference of a memory demonstrative as actually provided by deep decentring to the past time. To understand the memory demonstrative is to simulate the time at which a past perceptual demonstrative could have been used. If you think of knowledge of the reference of the memory demonstrative in this way, then I think you can see how it could validate the use of the kind of introduction rule I mentioned for memory demonstratives. The crucial point is that deep decentring is not simply a matter of knowing how to verify or to find the implications of the demonstrative proposition. It actually provides you with knowledge of which thing is being referred to. It is what causes, and justifies, your use of the particular methods that you use to verify or find the implications of judgements involving the demonstrative. 4. A Relational View of Memory Suppose that your local garage is staffed by a number of people who come and go over the years, and that to varying degrees you have minor exchanges and conversations with many of them, although rarely if ever do you reach the point of finding out anyone's name. Years later, with your feet up on the verandah, you may suddenly recall one particular mechanic, and think: 'I' wonder what became of him? That man once told me he always went on holiday to Plymouth. And I once saw that man in a fight

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with a thief.' Here we have fairly pure uses of a memory demonstrative, 'that man', referring to someone who may by now be dead. It seems evident that, as I put it in Chapter 5, section 4, in this case we can have 'trading on identity' in inferences involving uses of the memory demonstrative, 'that man'. That is: from the two premises, for example: 'That man always went to Plymouth on holiday', and 'That man was once involved in a fight with a thief, you can immediately infer that someone who always went on holiday to Plymouth was once involved in a fight with a thief. You do not need a further premise explicitly asserting that it is the same man in question both times; the proposition 'That man is that man' is simply an instance of the logical law of identity, and there is no need for any such premise to be invoked for the argument to be valid. Nonetheless, consider the past perceptual judgements from which these memory judgments may derive. As you stand waiting for your car keys and listening to the mechanic's holiday plans, you think, 'That (perceived) man always goes to Plymouth on holiday'. Perhaps a few hours later, perhaps a year later, you come upon the scene just as a robber tries to escape from the garage, and you think, 'That (perceived) rnan is in a fight with a thief. But here the identity judgement is not trivial. It may no doubt be easy enough to recognize him as the same man again, for an ordinary subject such as yourself. But the identity judgement 'That man (perceived as you wait for your car keys) is identical to that man (perceived as you come upon the struggle with the robber)' is not merely an instance of the logical law of identity; it needs some empirical skill to verify that identity proposition, even if it is only the use of an ordinary ability to recognize people when you see them again. How can this have happened? The use of the memory demonstrative in the two memory judgements is just the same, so that the trading on identity is legitimate, whereas the memory judgements derive from two quite different perceptual judgments, in which different perceptual demonstratives are used, so that trading on identity is not legitimate. How can it have happened that a single memory demonstrative is the descendant of two quite different perceptual demonstratives? In the last section, I said that we should think of the memory experience that you use in interpreting a memory demonstrative as involving deep decentring to a past perception. I think that what our current problem shows is that we should not in general think of this deep decentring as involving decentring to a past perception which you actually had. Memory images are not simple copies of past perceptions. If they were, there would indeed be a puzzle about how a single memory-experience could simultaneously be a copy of two quite distinct past perceptions. But rather than being simple copies of past perceptions, memory images are reconstructed

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from compilations of past perceptions. This is immediately apparent when you reflect even on the contrast between the course of your perceptions as you enter a room—jerky, rapidly switching from shot to shot, disorganized—and your imagistic memory a few moments later of your entry to the room, which is a smooth, carefully edited, coherent sequence. The constructed character of memory imagery—the fact that we cannot view the memory image as a simple copy of an earlier perception—also shows up in the fact that many people, reporting the contents of their memories of scenes in which they played a part, report that they have a third-person image of themselves as one among the people in the scene, rather than remembering the scene from their own past point of view (Nigro and Neisser 1983). Finally, there may be no one past perception from which your current memory image derives. Suppose you are asked, 'Do you remember that woman who sold flowers by the railway station?'. You may well be in a position to understand the memory demonstrative here, but there may be no one past perception from which your current memory image of that woman derives—it may be that your memory imagery of that woman, which you use to interpret the demonstrative, is in effect a compilation from many past perceptions of her, which you could not now separate. Nonetheless, memory images are still linked to past perceptions. It sometimes seems to be supposed that memory is somehow discredited by the fact that it has this reconstructive character, as if the point of the reconstruction were inevitably to distort your memories of how things happened. Of course there can be distortion. But the point of the reconstruction is more typically to keep your memory images on track; to ensure that they are credible images of what actually happened. In effect, what you are doing is constructing an image of the past scene which could have been the content of an accurate perception of it, whether or not there was just such a perception. What I am proposing, then, is that we should think of memory experiences in general as involving deep decentring to possible, rather than actual, past perceptions. By saying this, I am not arguing that the remembering subject can simply invent any kind of past perception—that would obliterate the distinction between memory and imagination. Rather, the range of possible past perceptions in question is quite tightly controlled, principally by the subject's own past perceptions of the scene. The remembering subject is decentring to past perceptions which an ordinary observer could have had of the remembered scene. Earlier I said that the introduction rule for a memory demonstrative would be something like: That (perceived) man is drenched [judged on Monday] That (remembered) man was drenched [judged subsequently]

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What I am suggesting now is that judgements involving memory demonstratives need not typically depend on an actual application of this rule. Judgements involving memory demonstratives may typically depend, rather, on the subject being in a position to judge that there could in principle have been a correct use of this rule, in the past situation. When, in the disciplined way I suggested, the subject forms a memory image of the past scene, in effect what is happening is that the subject is deep decentring to a possible past perception, which could have been used as the basis for the formation of a past perceptual-demonstrative judgement which would serve as the input to a correct application of the introduction rule. This is, of course, a quite general point about introduction rules. To establish a proposition of the form, 'A or B', the standard introduction rules would suggest that you must have established A or established B. But you do not always have to proceed in that way. It will do if you can establish that in principle, you could have established one or the other, even though you did not in fact establish either. Similarly, the fact that the standard introduction rule for a memory demonstrative requires that you have established a suitable past perceptual-demonstrative judgement does not imply that the only way to establish the memory demonstrative judgement is to have first established the relevant past perceptual-demonstrative judgement. It is enough if you can establish that, in principle, you could have established a suitable past perceptual-demonstrative judgement. But that is what ordinary memory experiences, formed in the usual, epistemically sound ways, do establish: they allow deep decentring to a suitable past perceptual-demonstrative judgement. Does this approach favour the two-component view of conscious recollection over the direct acquaintance view? At first it may not seem that a direct acquaintance view could acknowledge any need for deep decentring in understanding a memory demonstrative, since acquaintance was thought of as a primitive relation between the present rememberer and the past object, which would not be mediated by any representation of past perceptions. On a two-component view, on the other hand, the current conscious image just serves as the basis for deep decentring. The current conscious image is a potential perceptual image, and knowing the temporal and spatial context for the image just provides for the second phase of deep decentring. So the two-component view of conscious recollection and the view of grasp of a memory demonstrative as involving deep decentring seem to support one another. The argument for a Relational View of perceptual experience that I emphasized in earlier chapters was that only the Relational View can acknowledge the role of experience in making the categorical object itself available to the subject. But that argument cannot apply directly to the case

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of memory demonstratives: a memory of a perceptual confrontation with the past categorical object need not itself be a confrontation with the categorical object. Still, the points I have just been making do show that grasp of the memory demonstrative requires the existence of the past object. Since the use that we make of memory demonstratives depends in general on compilation of images, the correctness of your current use of the memory demonstrative will depend on whether you have compiled together perceptions that are indeed all perceptions of one and the same object. So your grasp of the memory demonstrative will depend on its being true that there is just one object from which your current memory derives. And that in general will not be something that can be guaranteed by the contents of your memory images or perceptual images alone—they could be exactly the same whether they derived from one object, a number of objects or no objects at all. Whether your grasp of the memory demonstrative can justify the use you make of it will depend what objects there are around you. So since grasp of the memory demonstrative has to validate your using the demonstrative as if there is just one object in question, your having grasped the memory demonstrative at all will depend on the existence and uniqueness of the thing from which your memory images derive. A view which would accommodate all of these points would be one on which (a) your current experience, in memory, of the past object, reaches all the way to the past object itself. That is, just as on Russell's original theory, the memory experience includes the past object as a constituent, so that there is a sense in which the existence and uniqueness of the object referred to is apparent to the subject. Nonetheless, (b) there is a further aspect to your current experience of the past object, the 'way' in which the past object is given to you, which does provide you with the capacity for deep decentring to a past perception of the thing. For memory demonstratives, just as for perceptual demonstratives, there will have to be some 'bundling' principle—the analogue of a binding principle—that is what memory uses to put together the information true of a single object. And that will define the 'way' in which the past object is given in memory. 5. Top-Down vs. Bottom- Up Memory Demonstratives There are two reasons why perceptual demonstratives seem to be fundamental to our grasp of concepts and language. One is that they play a basic role in our understanding of observational concepts, which are first introduced and explained in the context of propositions involving perceptual demonstratives. The second reason is that perceptual demonstration seems

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to be fundamental among the types of singular reference. It does not itself depend on the availability of other types of singular reference; but other types of singular reference, such as our use of proper names, seem to depend on their connections to perceptual demonstratives. Do similar points apply to memory demonstratives? Do they have any claim to be fundamental to our grasp of concepts and language? Do memory demonstratives have any role in explaining observational concepts? On the face of it, the answer seems to be that they can play a role in explaining observational concepts, but that they need not do so. For example, if you are trying to explain to me what 'Wedgwood blue' is, you might say, 'Remember that room we were in yesterday? Those walls were Wedgwood blue'. But this does not give memory any special place in the explanation of observational concepts. It. can play its role here only because of its link to perception; only because when I say 'those walls' I am deep decentring to perception of those walls as they were yesterday. Are memory demonstratives fundamental among the types of singular reference? I think that here we have to make a contrast between different ways in which a memory image might be constructed. In one kind of case, you have a clear objective in constructing a memory image, which is defined by some non-demonstrative designator such as 'Jerry Lee Lewis'. Suppose I am trying to remember what Jerry Lee Lewis looks like. I construct an image of him, using the stored information I have. Once I have a vivid image, I might say, 'That man is probably dead by now', using a memory demonstrative. But there does not seem to be any sense in which this memory demonstrative is any more fundamental than the name, 'Jerry Lee Lewis'. The judgement, 'That (remembered) man is Jerry Lee Lewis', is a priori. In contrast, perceptual demonstratives seem always to achieve reference independently of our capacities to identify objects descriptively, or to recognize them. So a judgement like 'That (perceived) man is Jerry Lee Lewis' is always empirically grounded rather than being a priori. In the case in which I form an image of Jerry Lee Lewis, the objective in constructing the memory image on which the memory demonstrative depends is specified using a non-demonstrative designator. We might call such memory demonstratives, 'top-down memory demonstratives', because there is a top-down specification of the intended referent governing the construction of the memory image. There are also, however, 'bottom-up memory demonstratives'. Suppose we return to the scenario on which you and 1 are standing talking in a shop doorway during a heavy rainstorm, and as we talk, a bedraggled figure stumbles into shelter. The next day you say to me: 'Do you remember that man in the shop doorway yesterday? He was really drenched.' In this case ! understand your use of the demonstrative by consciously recollecting that bedraggled figure. My

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formation of the memory image here is not top-down, in the sense that I have an objective in forming the memory image which can be specified using a non-demonstrative designator; though you are certainly supplying me with retrieval cues. My aim is simply to form an image of the scene in the doorway, and consequent upon that, I can refer to that individual as 'that man'. There is in this case no designator D such that I express a priori knowledge when I say 'That (remembered) man is D'. So this is a bottomup memory demonstrative. The use of bottom-up memory demonstratives does not seem to depend on the use of any other types of singular reference. So in that sense they might be said to be basic. They do not yet, however, seem to have any claim to being fundamental, in the sense in which perceptual demonstratives are fundamental. That is, we do not yet have any reason to think that other types of singular reference depend on the use of memory demonstratives. The most intriguing and problematic line of thought here was once again set out by Russell. Explaining the need for experiential memory of past objects, Russell wrote: But for the fact of memory in this sense, we should not know that there ever was a past at all, nor should we be able to understand the word 'past' any more than a man born blind can understand the word 'light'. Thus there must be intuitive judgements of memory, and it is upon them, ultimately, that all our knowledge of the past depends. (Russell 1967: 115)

We can imagine someone who claims to have no experience of the past, in Russell's sense. This person might be able to construct memory narratives which reliably reflect the course of events. The question raised by Russell's remark is whether there is not here a sense in which this is just empty talk. (Similarly, someone born blind might, one way or another, manage to use a colour vocabulary reliably; but he would have no grasp of colour concepts and this would just be empty talk.) Certainly, it is hard to see how someone who had precognition, but no experiential memory, could have the concept of the past. But although it has some immediate plausibility, it is not easy to see how you would make out a detailed case for Russell's view here. Moreover, this view immediately raises a problem. As I said, we do not have experience of the future in the sense in which we have experience of the past. But we certainly have the concept of the future. Why should there be this asymmetry between past and future? If you think that we do need experience of past objects in order to have the concept of the past, you owe an explanation of why we do not need experience of future objects in order to have the conception of the future.

10 The Anti-Realist Alternative So far, I have been arguing that knowledge of the reference of a demonstrative referring to a currently perceived object is provided by your conscious attention to the object. I argued that conscious attention to the object provides a knowledge of reference which causes and justifies the pattern of use that you make of the demonstrative. In the last two chapters, I have been looking at how we can extend the approach to joint attention and memory demonstratives. The traditional objection to this Classical View is that there is no such thing as knowledge of reference, over and above the use that we make of a term. All it can come to, that you know the reference of a term, is that you know how to use the term. This line of thought has been pressed hard by Michael Dummett; I will consider his arguments on this point in section 2 of this chapter. So long as we think in terms of the Classical View, of there being such a thing as knowledge of reference, we could suppose that the use of language has ends which it may attain more or less successfully, and that the justification or criticism of a way of using language would appeal to whether or not it achieves those ends. Without the notion of knowledge of reference, it is not easy to see how standards of correctness are to be set. If there is only the use, and no knowledge of reference with which the use must keep faith, how can there be any such thing as a right or wrong use? The guiding idea in Dummett's The Logical Basis of Metaphysics (Dummett 1991) is that our total linguistic practice involves a multiplicity of principles for getting from one state to another, a multiplicity of transition rules. There are principles which we use in verifying statements, and principles which we use in drawing consequences from statements. And for the linguistic practice to be in order, all the various principles we use must be in harmony with one another. In that book, Dummett's concern is with the demand for harmony between the introduction and elimination rules for a logical constant. Given a particular set of introduction rules, we do not want the elimination rules to allow us to derive unwarrantedly strong conclusions, but we do want them to allow us to derive all the conclusions we are entitled to. And

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as so often, this discussion of logical constants provides an illuminating model for discussion of perceptual demonstratives. So I will set out the account of logical constants in section 1, then look at how it would apply to demonstratives in section 3.

1. Harmony for Prepositional Constants Suppose we have an introduction rule for each logical constant. This tells us when a statement with that constant as its principal operator is justified, in terms of the conditions under which the sub-sentences are justified. Call an argument canonical if it begins with atomic sentences as premises and uses only these introduction rules. Then we can say that an arbitrary argument, perhaps with complex premises, is valid if, given canonical arguments for its premises, we could construct a canonical argument for its conclusion. Using this procedure, we could justify the elimination rules for the logical constants. For example, given the introduction rule for 'A&B', any canonical argument for 'A&B' will let us derive a canonical argument for A and a canonical argument for B, so the elimination rules are justified. We can also have a procedure which takes the elimination rules as basic. An arbitrary argument will then be valid if any atomic consequence that could be drawn from its conclusion, using only the elimination rules, could already be drawn from its premises, using only the elimination rules. We can use this idea to evaluate proposed introduction rules. For example, suppose we have the usual or-elimination rule, taken as given. Consider now the usual or-introduction rule. The upshot of any application of the introduction rule will be a statement with 'or' as its principal operator, to which we can apply the elimination rule. But any conclusion that we get by applying elimination rules here could also have been obtained by applying elimination rules to the premises of that application of the introduction rule; and that validates the introduction rule. This gives an extremely powerful way of justifying or criticizing the use of a term. For example, suppose we consider the new logical constant '*', for which I stipulate that the rules of inference are as follows. The elimination rule is:

[A]

0

[B]

C

¥ C

A*B

C In other words, if from A together with other premises 0 you can derive C, and if from B together with other premises ¥ you can derive C, then you can

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derive C from 0, ¥, and A*B alone. This is the same elimination rule as for 'or'. And the introduction rule for '*' is:

A

B A*B

In other words, to establish A*B you need to have both A and B. So this is the same introduction rule as for 'and'. It is not hard to feel that things are not well with this pattern of use. If you are going to be so reserved about what you infer from A*B, why should you be so demanding about what you require to establish it? And if so much is required to establish A*B, why do you have to be so cautious in what you infer from it? The problem here is not that you are going to find some contradiction. It is really more basic than that. You do not know what someone is saying when they make a statement of the form 'A*B'. Suppose someone you trust implicitly says to you, 'Your talk was terrific * it's raining again'. Should you be pleased? On the one hand, you know that he wouldn't have said that unless he had established both 'Your talk was terrific', and 'It's raining again'. That might lead you to conclude your talk had not been so bad after all. On the other hand, though, you cannot infer A from A*B; that is what it means, that the elimination rule is the same as for 'or', rather than 'and'. So you know that you have no licence to infer that your talk was terrific, even though you accept his statement. So what has he said to you? Dummett's diagnosis of the problem here is that the introduction and elimination rules are not in harmony. Given the introduction rule, you could validate stronger elimination rules: since you had to establish A and to establish B to establish A*B, any canonical proof of A*B would provide a canonical proof of A and a canonical proof of B, so you could validate the elimination rules, from A*B to infer A, and from A*B to infer B. Alternatively, if you took the above elimination rule for '*' as given, you could validate a weaker introduction rule. Suppose that from A*B (together with premises 0 and ¥), you can infer C, using the elimination rule. That means you must be able to derive C from A (together with 0). So any conclusion you draw from A*B, using the elimination rule, could already have been derived from A itself. That is enough to validate the introduction rule, from A itself to infer A*B. And this is less demanding than the above introduction rule. Similarly, you could validate the introduction rule, from B itself to infer A*B. Consider now the case of classical negation. The elimination rule is, from not-not-A to infer A. That will validate the introduction rule, that

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from A we can infer not-not-A, and that is all; it does not show how to validate any other introduction rule. The introduction rule we want, for classical negation, is that if, from A as hypothesis, we can derive not-A, then we may discharge the hypothesis that A and conclude not-A. Can we take that introduction rule as given, and use it to justify the elimination rule? Evidently not: to obtain the premise of an application of the elimination rule, not-not-A, we need to derive not-not-A from the hypothesis that not-A. But that does not of itself give us a way of deriving A by use of the introduction rules alone. So it does seem that by this criterion, the classical rules for negation are not in harmony with one another. It is at this point that we see most simply and vividly the difference between an approach in terms of harmony and the Classical View. On the Classical View, there really is no demand for harmony, and the introduction and elimination rules have to separately keep faith with the truth-table for the constant, rather than standing in any particular relation to one another. So on the Classical View, the problem with '*' is not that the input and output rules are not in harmony with one another, but that you cannot write a truth-table for '*' which will validate just these rules. Any truthtable which validates one of the rules will fail to validate the other rule. On a Classical View, the case of negation is quite different. Here there is a truth-table which plainly does validate the classical introduction and elimination rules; and on the Classical View, that is all that matters. Whether the rules are in harmony with one another is neither here nor there. The whole thrust of the anti-realist critique of the Classical View, though, is to sweep aside the idea of knowledge of reference as providing something with which use must keep faith, and to hold that the only normativity we can find here is in the demand that the different aspects of use be in harmony with one another. So, on the anti-realist view, '*' and classical negation are each as bad as the other. On Dummett's approach, for classical negation to be coherent, the introduction and elimination rules must be in harmony with one another. He does not, however, immediately draw the strong conclusion that classical negation is not coherent. All we have established so far, after all, is that we cannot, merely by reference to the rules themselves, see them to be in harmony with one another. Therefore, Dummett says, these rules cannot of themselves explain the meaning of negation; they do not provide enough for us to see that the use of the term is coherent. It remains possible, though, that there are non-logical principles, relating to the specific meanings of the specific sub-sentences to which we apply negation, from which it follows that the inputs and outputs to negated judgements can indeed be

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seen to be overall in harmony. This remains, though, only an abstract possibility, and there is no particular reason to suppose that classical negation can indeed be validated in this way; it would be hard to know where to begin. It seems reasonable to ask whether there is on a Classical View any role for harmony in justifying or criticizing the pattern of use that we make of a term. I have said that if we are operating with a classical picture, there is no reason to accept the demand for harmony; all we can ask of the transitions we make is that they be truth-preserving, or separately justifiable by appeal to the references of the terms involved. Where harmony plainly does matter is if we plan on giving only a syntactic explanation of a logical constant, if we are only going to give introduction and elimination rules for it in order to explain it, with no semantic foundation. A logical constant so understood is really just a trick to facilitate inference, and what we want to be sure of is that its use will do no harm; at the same time, we would like to be sure that we are getting as much as we can out of the device. The prooftheoretic account explains how to secure precisely that, though how exactly we apply the account may depend on some semantic presuppositions and ultimately upon a theory of meaning (Dummett 1991: 270). But this applies only to the case in which we are trying to rest with a purely syntactic account of the functioning of a constant. I do not think we can make anything of the idea of formulating criteria of harmony that would, as Dummett hopes, be purely syntactic, yet provide unconditional and quite general demands on any pattern of use, even for terms whose reference we know. The idea of justifying a pattern of use by showing it to be a conservative extension of some pre-existing practice only makes sense if we think of ourselves thereby showing we have remained faithful to the notion of truth that we have for the pre-existing practice. The natural interpretation of such a situation is that the extended language is not to be taken at face value: it does not deal with a separate domain of reality, but merely provides an instrumental way of organizing our thought in the pre-existing practice, which is where we find the hard facts. If it is to be a general demand on the use we make of terms, harmony cannot be understood as a relation holding simply between sets of transition rules; the question we must always ask is whether those transition rules are serving the purpose to which we put them. And we cannot understand what the point is of a set of inference rules without appealing to the truth-conditions of the statements involved. The upshot of applying the inference rules is assertion of the conclusion. And as Dummett himself has often said, truth just is that which is the aim of assertion.

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2. Dummett's Three Arguments Why should we settle for an approach in terms of harmony? What problem is supposed to arise if we think of the pattern of use that is made of a term as being caused and justified by the knowledge of reference possessed by the subject? Dummett presents three lines of objection to the idea that pattern of use is responsible to knowledge of truth-conditions. The first is that we cannot in general give any explanation of what it is to grasp the truthcondition of a sentence. This is particularly vivid, he says, in the case of undecidable sentences: sentences about inaccessible regions of space-time, such as the past and the spatially remote; sentences involving unbounded quantification over infinite totalities, such as all future times; and uses of subjunctive conditionals. Grasp of the truth-condition of such a sentence cannot be taken to be a capacity to recognize that it is true whenever it is true; there is no guarantee that one will be able to do that. But nor is it a matter of being able to state explicitly what the truth-condition is, since one cannot in general state the truth-condition of an undecidable sentence in other terms. These questions go well beyond the scope of the present discussion, which is focused on simple propositions about what we can observe. Even so, consideration of these further cases has to be grounded in an accurate account of the observational cases. It has to be grounded in the point that even in the observational case, reference and verification do not collapse into one another. Even in the observational case, we can give an account of what knowledge of reference, classically conceived, consists in. The challenge was to say what this knowledge of reference consists in, if it is more than an ability to use the proposition. But we have answered that question: this knowledge of reference is provided by conscious attention to the object. If we had only a functionalist characterization of conscious attention to objects, then Dummett's argument on this point would be, I think, conclusive. What does it come to, that you are consciously attending to an object? On a functionalist account, it comes to this: you are now in a position to verify propositions concerning that object—to answer questions about it—and to act on that object. But that just is a matter of the use you can make of the demonstrative. Conscious attention, so conceived, would not provide a standard to be met by your use of the demonstrative; it would not define the objective at which you were aiming in the use that you made of the demonstrative, in verification or action. We have seen, though, that there is no need to accept this functionalist characterization of conscious attention to an object. We do have to appeal to experience of the world in explaining how it is that we have the conception of objects and properties as categorical, rather than merely as

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complexes of dispositions. And conscious attention to the categorical object is not to be cashed as a matter merely of how you go on in your use of a demonstrative; if we think of conscious attention in these functionalist terms, we lose sight of how it could play any role in making available the conception of categorical objects and properties. All that conscious attention could provide, on a functionalist conception of conscious attention, would be the conception of the object as a complex of dispositions. I have argued in particular that we ought to think of conscious attention in relational terms, of the object itself as a constituent of the experience, rather than as merely being represented in one way or another. This makes it particularly vivid that the conscious state is not to be characterized simply in terms of an ability to verify or to act on the object. But even if you resist this conception of experience, you can still acknowledge the role of conscious attention in explaining why we make the use of the demonstrative that we do, rather than simply consisting in a tendency to use the demonstrative in one way or another. Secondly, Dummett argues that we cannot regard our capacity to verify and find the implications of statements as derived from our grasp of truth conditions. We cannot take knowledge of the meaning of a term as a matter of grasping an algorithm which instructs us how to apply it. The force of this line of objection is most easily seen in the case of the propositional constants. The argument is that even if you get past the first line of objection—that we cannot say what it is to grasp the truth-table for a propositional constant, other than it simply being a matter of knowing how to use the constant—there is no way in which knowledge of the truth-table could supply a foundation for your use of the logical constant. To derive the use of the term from the truth-table, you would already need to use logical inference in the derivation, either using the constant itself or some other constants to which the same point would ultimately apply (Quine 1976). Applied to demonstratives, the challenge is that even if you did manage to make a distinction between knowing how to use a demonstrative proposition and knowing the reference of the term, you could never connect the two up again. You would not be able to explain the connection between being able to verify or act on the basis of propositions involving the demonstrative and knowing the reference of the term. The reply to this objection is, however, immediate from our discussion so far. Conscious attention to the object can cause and justify your use of particular methods of verification of demonstrative propositions; this relation of 'causing and justifying' is all the connection we need. It is your conscious attention to the object that is causing particular information-

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processing procedures to swing into play to allow you to verify propositions about the object, or to act on that object. And the fact that you are consciously attending to just that object is what allows us to justify or criticise the particular information-processing procedures that have swung into play: it allows us to assess them in terms of whether or not they are successful in providing verification concerning or action on that particular object. Conscious attention defines the objective of the information-processing procedures. (For brief remarks on the parallel with the case of truth-tables and the propositional constants, see Chapter 5, section 5.) Dummett's third line of objection to the Classical View is an appeal to the need for our understanding of language to be shared, that we have the right to be sure that communication will not break down. The problem for the truth-conditional theorist is that he attempts to provide a foundation for that right, in our all associating the same truth-conditions with sentences. But this raises the question how we know that we all do associate the same truth-conditions with the same sentences, and at that point the truthconditional approach lets us down. As Dummett remarks, 'The right thing to say, from a Wittgensteinian standpoint, is that communication is in no danger of breaking down, and that this is one of the things of which we are entitled to be sure, but that our assurance does not rest on anything' (Dummett 1991: 311). Applied to the case of demonstratives, this third objection is that if we did manage to distinguish between being able to verify a demonstrative proposition and knowing the reference of the demonstrative, we would be left with the conclusion that no one knows what anyone else is talking about. All we can observe of each other are the ways in which we verify or act on the basis of demonstrative thoughts. Since conscious attention to the object, providing knowledge of the reference of the demonstrative, is supposed to be something over and above a capacity to verify demonstrative propositions or to act on the basis of demonstrative propositions, it follows, according to Dummett, that it is something of which we can have no knowledge in one another. In present terms, that amounts to the claim that you cannot know what other people are consciously attending to. And there seems to be no reason at all to believe that. Which objects the other person is attending to seems to be as fundamental and as evident as any facts about what uses he is making of the propositions he understands. Moreover, on the relational picture, it is the very same objects that he is attending to as I am attending to. So there is no mystery about the intrinsic nature of the other person's conscious attention. Certainly acknowledging the possibility of joint attention, as I described it in Chapter 8, does not depend on accepting a functionalist view of conscious attention.

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There is a point of strong agreement between Dummett's approach and the one I have been recommending. Both approaches agree that we should not view the patterns of use that people make of the concepts they possess as patterns of use whose justification is entirely unknown to those people. Rather, on both Dummett's approach and the one I have been recommending, there is a justification to be given for the pattern of use of a term, and an understanding of the term consists in a grasp of the justification for that pattern of use. The divergence between Dummett's approach and the Classical View is in the content of the justification and the way in which it is grasped. On my view, the inputs and outputs to the demonstrative judgement need not themselves be consciously available. Conscious attention to the object causes and defines the objective of the pattern of use, but that is consistent with my having no knowledge of what that pattern of use is. On Dummett's account, though, there is no such level of knowledge of reference, causing and justifying the pattern of use. There is only the pattern of use, which may or may not be harmonious. So if the thinker is to grasp the validation of the pattern of use, she can do it only by knowing what the pattern of use is. This already puts some pressure on Dummett's account, since it is by no means apparent that there is any psychological reality to the idea that the subject has an overview of the pattern of use of a demonstrative and a grasp of it as harmonious. The Classical View need not maintain that all patterns of use may be inharmonious. For example, on a classical account of 'and', the introduction and elimination rules really will be in harmony with one another, and anyone who uses inharmonious rules for 'and' will be making a mistake. But, on a Classical View, that is not because there is a fundamental demand for harmony. Rather, there being harmony in the pattern of use is a consequence, a by-product, of the demand that the introduction and elimination rules should each independently keep faith with the truth-table: that is, the rules should be truth-preserving, and the introduction rules should be as undemanding as possible consistent with truth-preservation, and the elimination rules should be as permissive as possible consistent with truthpreservation. Similarly, a Classical View of demonstratives need not maintain that the pattern of use of a demonstrative is in general inharmonious. Rather, if there is harmony in the use of a demonstrative, that is not fundamental, but a consequence of the fact that the introduction and elimination rules for the use of the demonstrative have independently to keep faith with the subject's knowledge of the reference of the demonstrative.

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The anti-realist may accept that the introduction rule for a demonstrative is: Feature F at location p That cup is F and the elimination rule is: That cup is F If you'd like F-ness, move towards whatever is at position p And the normative issue is whether the input and output rules are in harmony with one another. On the face of it, there is harmony here, since the binding parameter used in the introduction rule—'location p'—is the same as the binding parameter used in the elimination rule—'position p'. The same binding parameter will ideally be used in identifying the target of visual perception in verifying propositions about the object and in identifying the target of the visuomotor system for action on the object. As we saw in Chapter 5, this is a simplification of the rules of inference we can expect there to be for a demonstrative; but for present purposes, I do not think that the simplification affects the main points. Now, of course, a demonstrative such as 'that cup' is not itself a logical constant. So by Dummett's lights, it will be legitimate to suppose that harmony in the use of the demonstrative is secured as an empirical matter, by the kind of empirical considerations Dummett thinks a defender of classical logic might appeal to in trying to show that classical negation is after all harmonious. The non-logical character of demonstratives will emerge vividly the moment we think about the possibility of reference failure, or the empirical consideration involved in keeping track of a single object over time. But suppose we just focus on the question whether the ordinary subject has knowledge of harmony when using a demonstrative. We do not in practice operate in such a way that the parameters for action are set by the perceptual input that we use in verifying propositions about perceived objects. As we saw in Chapter 3, conscious perceptual illusions regarding a perceived object can leave intact your ability to act on that object. So even in the veridical case, there is no reason to suppose that the parameters for your actions on the thing are being set directly by your conscious experience of the object. We do not in practice regulate the inputs to and outputs from demonstrative propositions by appeal to one another. Rather, the inputs and outputs are each independently regulated by appeal to the object itself, onto which our experience locks by means of a complex binding parameter. So on Dummett's account, our practice in using demonstratives as we do is subject to criticism in the same way as our

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practice in using classical negation. In this case, it is not that the upshot of the process is necessarily the use of inharmonious rules. It is rather that such harmony as we find is a consequence of something more fundamental: namely, the introduction and elimination rules individually keeping faith with your conscious attention to the object.

4. The Basic Fragment Suppose we go back to the objection to classical semantics which says: we do not have any explanation of what it is to grasp the truth-condition of a sentence. In particular, we cannot explain what it is to have a conception of the truth of a sentence under which every sentence is, determinately, either true or not true. Dummett says the point is most pressing in the case of undecidable sentences, such as sentences about the past, or counterfactuals, or sentences about infinite totalities. The classical semanticist cannot explain knowledge of what it is for such a sentence to be true as a matter of being able to recognize the sentence as true when it is true, since in general there is no presumption that you will be able to recognize the truth of such a sentence. Nor can it be a matter of being able to paraphrase the sentence, since in general we cannot paraphrase the sentences we understand. Now, Dummett's argument at this point is often thought to be an appeal to a kind of behaviourism about meaning, and a lot of time has been spent on whether behaviourism about meaning can be correct. But the issue of behaviourism is not to the point here. For it would be consistent with behaviourism to suppose that we can appeal to the patterns of inference a thinker regards as correct in finding which notion of truth he grasps. It is not just that we can recognize the sentences we use as verified in particular cases, or that we can sometimes give paraphrases of them. We also use those sentences in logical reasoning. And, you might argue, which notion of truth we have for those sentences is in part determined by which rules of inference we apply to those sentences. So if we apply classical logic to the sentences of our language, that is partly constitutive of our grasping a classical semantic theory for it. There is an early reply by Durnmett to this response which I think illuminating to consider here. Dummett's early reply to this response is that the notion of truth must not be allowed to become, in this way, a mere posit, hypothesized only in order to validate certain inferences which we do regard as correct (Dummett 1978: 317-18). And it is easy to see the argument here. For this procedure seems to rob the notion of truth of any capacity to validate the correctness of particular patterns of inference. But the whole point of appealing to the speaker's knowledge of a semantic

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theory was to explain his ability to understand why the forms of inference he uses are correct. So what notion of truth do we have for the sentences of our language? In answering this question, we are not to appeal to the fact that we actually use various particular forms of inference. We have to look at the notion of truth we have for the atomic sentences of the language, and the notion of truth we have, established in our understanding of the atomic sentences alone, and then our grasp of that notion of truth can be presupposed by the semantic theory we construct for the logical constants we introduce. The key point in Dummett's argument now is: If we consider a fragment of a natural language lacking the sentential operators, including negation, but containing sentences not effectively decidable by observation, it would be impossible for that fragment to display features embodying our recognition of the undecidable sentences as determinately true or false... A very clear case would be that of the past tense in a language in which there were no compound tenses, and in which the past tense, considered as an operator, could not be subjected to any of the ordinary logical constants: in such a language nothing could reveal the assumption that each statement about the past was determinately either true or false. (Dummett 1978: 316-17)

The conclusion of this argument is that we simply do not have the notions of truth and falsity which are presupposed by classical semantic theory. Suppose for the moment—but only for the moment—that we grant that the basic semantic notions have to be established in a logic-free fragment of language. What does this tell us about the notion of singular reference? A language without logic would of course be very primitive. It is hard to see how there could even be singular reference. For there would be no quantification, and there would be no complex predication: it would be impossible to make inferences such as 'a is F; a is G; so, a is both F and G'. And without logically complex predicates, it is hard to see with what right we could claim to find singular terms in the language. All we would have would be feature-placing sentences, such as 'Rain!' or 'It was cold'. Many philosophers—Ayer, Dummett, Strawson, and Quine—have thought that there is a level of language use that is more basic than the level at which we have reference to objects. This is the feature-placing level of discourse, at which we have a use of predicates to report the presence of features in the environment, without any reference being made to objects of which these are features. To use an example from Strawson 1971, we can have a level at which a child can use the term 'Cat! to report the presence of cat, without having the distinction between one cat and two, or any understanding of the question whether the cat he is now encountering is one and the same as the cat he encountered earlier. The child might indeed use 'Cat!' as a mass term, and distinguish between the case in which there is only a limited

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amount of cat around and the case in which it has become unbearably catty, as it were. But that would not involve the child in singular reference. On this approach, our talk of objects depends on this more primitive level. Understanding of an atomic proposition 'a is F' depends on an understanding of it as following from a pair of statements, the subjectless identification-statement, 'This is a', and the subjectless feature-placing statement, 'This is F'. You have understood the atomic statement when you know how to verify it; and you verify it by the two-stage process of checking that what is before you is indeed a, and by checking that what is before you is indeed F. To get to talk of objects, according to Dummett, we have to explain 'when it is right to point in two different directions on the same occasion, and say "This is the same X as that"; and when it is right to say things like "That is the same X as the one which we saw on such-and-such a previous occasion'" (Dummett 1973: 572-3). There is a broad sense in which this is a constructivist view of singular reference. All of our talk about objects is constructed from talk at the more basic feature-placing level. So the notion of reference we get will not be the one used by a classical truth-conditional semantics. As I said, it is hard to see how you could have anything other than a verificationist or pragmatist account of our understanding of feature-placing discourse. And therefore it will be hard to see how you could have anything other than a verificationist or pragmatist conception of reference by this procedure. However, having reached this point in Dummett's argument, a reply is ready to hand. Dummett in effect offers a choice. On the one hand, we can think of reference to objects as defined in terms of talk at a more basic featureplacing level, and face the significant difficulties of (a) characterizing what conceptual resources are available at the feature-placing level (to take just one crucial issue, will talk of causation be available at the feature-placing level?), and (b) defining our ordinary talk of concrete objects in terms of whatever conceptual resources are thought to be available at the featureplacing level. It is not at all clear that this exercise could be completed. On the other hand, we can take the inferential patterns characteristic of singular terms as given, and postulate singular reference as what must explain the legitimacy of those familiar patterns of inference. This is the route that regards semantic characterizations of the language as involving the mere postulation of semantic value so as to allow favoured patterns of inference to be recognized as valid. But we do not have to take either route; we can resist the choice that Dummett offers. For we can regard knowledge of the references of a particularly basic class of singular terms, the perceptual demonstratives, as being provided by conscious attention to the objects referred to. On this approach, we do not have to construct singular reference from a more basic feature-placing level. But nor are we regarding the

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ascription of singular reference to a demonstrative as a mere posit to explain inferential behaviour. On the contrary, the knowledge of reference provided by conscious attention is at least as fundamental a datum as any supposed capacity we might have to use a logic-free fragment of language. 5. Spatial Reasoning and Mental Models This concludes my discussion of the relation between the approach to perceptual demonstratives in terms of conscious attention, and the anti-realist alternative. Dummett's programme also bears, however, on a topic we have touched on: our thought and reasoning about spatial properties and relations. So I want finally to look at the anti-realist picture of this case. As we saw in section 3 above, in discussing perceptual demonstratives, the strong point of agreement between Dummett and myself is that the ordinary subject does grasp the reason why certain transitions are valid and others not. There are then two types of dispute in which one might engage: (a) over which justifications can coherently be supposed to be available to the ordinary subject, and (b) over what strategies the ordinary subject is, as a matter of empirical fact, using to determine which transitions are valid and which are not. In section 3,1 argued that, in the case of perceptual demonstratives, the ordinary subject does not in fact use the kind of strategy that the antirealist recommends to determine which transitions are correct and which are not. Rather than aiming to match input and output directly with one another, the ordinary subject proceeds as follows. The subject aims to use the kind of input determined to be correct by the subject's own knowledge of reference—provided by conscious attention to the object—and the subject also aims to match output to that knowledge of reference. Conscious attention to the object provides knowledge of reference, which functions as a third element with which input and output must individually keep faith. So on issue (b), the anti-realist does not seem to provide an empirically correct picture of how subjects operate. And on issue (a), as we saw in sections 2 and 4, it is actually quite difficult to see what objection there is to the subject proceeding in this way. In this section, I want simply to indicate the ground we might have for rejecting the anti-realist's picture of spatial reasoning. To bring out what that picture is, though, I want first to look at one empirical account of how we do actually evaluate spatial reasoning. This is usually presented in the context of a classical account of the validity of spatial reasoning. But I will argue that the empirical findings—and indeed the empirical model—are, on the face of it, equally compatible with a proof-theoretic account of the

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validity of spatial reasoning. Once we fill out the anti-realist's account in this way, though, it will become evident that the anti-realist has serious difficulty in acknowledging that we can recognize one another to be all speaking and thinking about a single space. The anti-realist has to give a fundamental place to one's own grasp of an egocentric frame of reference, that leaves the subject apparently unable to formulate the conception of other people having their own egocentric frames of reference, on a par with his own. Anti-realism here leads to a kind of spatial solipsism. I begin, then, with the empirical investigation of the strategies that subjects use to determine whether transitions in spatial reasoning are correct. As we shall see, it is sometimes supposed that those strategies can only be strategies for determining whether those transitions are classically valid. In the next part of this section I will argue that this is not correct; those strategies could equally well be interpreted as strategies for determining whether the transitions are valid in the sense defined by the anti-realist, of being proof-theoretically correct. But reflecting on the picture to which this commits the anti-realist finally provides a deeper ground for rejecting the anti-realist's account. One task that you face as a cognitive subject in dealing with inferences in ordinary life is to determine which inferences are justified and which are not. A psychological theory has to describe the strategies that we actually use to determine which inferences are justified and which are not. So, following the distinction between classical and anti-realist views of the correctness of an inference, there are two different definitions we can give— model-theoretic and proof-theoretic—of the task that we have to accomplish. And then, once we have settled on a definition of which task it is that we are undertaking, there are various psychological theories possible of how we go about that task. (In effect, model-theoretic and prooftheoretic definitions of 'justified inference' are different task definitions at Marr's level 1, the computational level; different empirical theories of the strategies we use to accomplish those tasks are theories at Marr's level 2, the level of the algorithm (Marr 1982).) The mental models approach, developed by Johnson-Laird and his colleagues, is usually seen as a theory of the algorithm we use to determine which inferences are justified, in the model-theoretic sense. That is, the mental models theory is a description of how we actually go about determining which inferences are such that in any model in which the premises are true, the conclusion is also true. According to the mental models theory, there are three stages in determining whether a particular inference is justified. First, a 'model' of the premises is constructed, a 'model' in this sense being an analogue representation, in which a number

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of cognitive tokens bear relations to one another functionally isomorphic to the relations represented. Second, an informative conclusion is drawn, a proposition also true in that model. Third, there is a check to see whether there is any alternative model in which these premises are true and that conclusion false. This contrasts with a 'mental logic' approach, on which subjects apply inference rules to the premises, and the difficulty of an inference depends simply on the number of inference rules applied (for development and defence of this approach, see Rips 1994). The 'mental models' approach is usually supposed to be a description of an algorithm for finding whether inferences are justified in the classical model-theoretic sense, rather than being an algorithm for finding whether inferences are proof-theoretically justified. But we will see that this supposition is not compulsory. To see how the mental models approach works, consider the kind of empirical support that there is for the theory. Take, for example, the experiment performed by Byrne and Johnson-Laird 1989. This compares the relative difficulties of two problems: Problem 1 1. A is on the right of B 2. C is on the left of B 3. D is in front of C 4. E is in front of A.

Problem 2 1. B is on the right of A 2. C is on the left of B 3. D is in front of C 4. E is in front of B.

For both problems, the question set is: 'What is the relation between D and E?' In both cases, the answer is that D must be to the left of E. On a mental logic approach, Byrne and Johnson-Laird argued, Problem 1 should be harder than Problem 2, since it has a longer derivation than Problem 2. On a mental models account, however, the situation is the opposite. In Problem 1, only one model of the premises can be constructed, and in that model D is to the left of E. In Problem 2, however, there are two different models which could be constructed for the premises, depending on whether A is taken to be to the left or to the right of C. So unlike the case in problem 1, whichever initial model you constructed for the premises, at the third, falsification stage you will find that there is an alternative model of the premises, and you will have to check that in the second model, D is still to the left of E. So Problem 2 should be more difficult than problem 1, on a mental models approach. And indeed Byrne and Johnson-Laird found that 70 per cent of the answers provided by their subjects were correct for problem 1 and only 46 per cent for Problem 2. The whole point here is that construction of a mental model of the premises is taken to involve assigning A a definite location with respect to B. If the relative locations of A and B could be left indeterminate when constructing the model, that would be

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the best way to construct a model of the premises, and there would be no need for the construction of a second model. The need for construction of a second model arises only because of a presumption of determinacy. Johnson-Laird has always been quite explicit about the presumption of determinacy: A characteristic difference in the contents of mental models, images and propositional representations, concerns their specificity. Models, like images, are highly specific—a characteristic which has often drawn comments from philosophers. You cannot form an image of a triangle in general, but only of a specific triangle. Hence, if you reason on the basis of a model or image, you must take pains to ensure that your conclusion goes beyond the specific instance you considered. (Johnson-Laird 1983: 157)

As I said, it is easy to suppose that the mental models approach depends on classical semantic theory. However, we could interpret the mental models approach as explaining how it is that we do understand that any situation in which we can perceptually verify the premises of the inference is also a situation in which we could perceptually verify the conclusion of the inference. As Johnson-Laird says about the relation between mental models and imagery: images correspond to views of models: as a result either of perception or imagination, they represent the perceptible features of the corresponding real-world objects. In imagining, say, a rotating object, the underlying mental model of the object is used to recover a representation of its surfaces, reflectances and so forth, (Johnson-Laird 1983: 157)

A proof-theoretic justification of the types of inference above will have to show that any canonical proof of the premises guarantees that a canonical proof of the conclusion was available. We could then think of the role of mental models like this: we begin by imagining the kinds of perceptions that would verify the premises of a spatial inference. We consequently form a mental model of the configuration of objects involved, perhaps using an egocentric frame of reference. We then find whether it is possible for the model to generate the kinds of perceptions that would verify the conclusion. If it is possible for the model to do this, we then go back to find whether it is possible to construct alternative mental models on the basis of the perceptions which would verify the premises, and check whether any such alternative mental models can also be used to generate images of perceptions which would verify the conclusion. There is, then, no inexorable connection between a mental models approach to deductive reasoning, and a definition of logical consequence which is model-theoretic in the sense of the classical logician. Mental models theorists usually write as if their theory is a (Marr-level-2) theory of the

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algorithm being used to accomplish the task defined by a (Marr-level-1) classical logician using a classical model theory. But it is also possible to regard the mental models theory as a (Marr-level-2) theory of the algorithm being used to accomplish the task defined by a (Marr-level-1) account of logical consequence given in proof-theoretic terms. Consequently, we cannot take Johnson-Laird's findings to show of themselves that subjects are attempting to determine whether spatial inferences are classically rather than proof-theoretically valid. On the proof-theoretic interpretation of a mental models approach, it will have to give an especially fundamental place to egocentric frames of reference, because of their fundamental role in canonical proof of spatial propositions. So, for example, consider an instance of spatial reasoning which Dummett has often used, Euler's proof that anyone who crosses all the bridges at Konigsberg at least once must have crossed at least one of them twice. According to Dummett, the pattern of spatial reasoning here is justified as follows: An argument or proof convinces us because we construe it as showing that, given that the premisses hold good according to our ordinary criteria, the conclusion must also hold according to the criteria we already have for its holding . . . [W]e regard the proof as showing us, of someone observed to cross every bridge at Konigsberg, that he crossed at least one bridge twice, by the criteria we already possessed for crossing a bridge twice. (Dummett 1991: 219)

This implies that there is something basic about the ordinary egocentric frame of reference. The ordinary egocentric frame is what we use in ordinary perception, and spatial reasoning will typically involve beginning from the facts about the egocentric spatial locations and relations of perceived objects, and deriving ultimately further facts about the observable egocentric locations and relations of perceived object. A classical interpretation of spatial reasoning, in contrast, does not need to give any such fundamental place to the egocentric frame of reference, just because it does not give any fundamental place to the observational verification of propositions about spatial properties and relations. So there is no reason for the classical theorist to accept Dummett's analysis of Euler's proof. An alternative, classical diagnosis is that we are familiar with the conditions under which observation of an event is possible; we have some causal-explanatory understanding of how perception of events occurs. Armed with this understanding, we can find no reason why, if the traveller crossed a bridge twice, that should not be in principle observable. The analysis Dummett is suggesting in the above passage is quite different. On his analysis, the fact of the bridge being crossed twice is actually

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constituted by the possibility of observing it to have been crossed twice. That is the reason why the possibility of observing a bridge to have been crossed twice is guaranteed by the indirect proof, which uses observation of the traveller as having crossed each bridge at least once, together with Euler's proof. This second diagnosis is quite a radical anti-realist view. Of course, as Dummett points out, recognition of the possibility of indirect proof is a step towards realism and away from the extreme anti-realism which takes the obtaining of a fact to consist in our actually having a canonical proof of it. But it is still not realism. On this anti-realist view, the possibility of observing the fact to obtain is what constitutes the fact's obtaining. In contrast, according to the first diagnosis I suggested above, the possibility of observing the fact to obtain is grounded in the fact obtaining together with the conditions of observation being as they are. It seems to me that the emphasis that the anti-realist must put on the egocentric frame of reference ultimately means that the anti-realist cannot make sense of the fact that we all think of ourselves as occupying the same shared spatial world. I think we do have to acknowledge that the spatial prepositions, 'right', 'left', 'above', 'below', and so on are used with the same meanings in connection with any frame of reference; and the antirealist cannot explain how this could be so. Let me first make some remarks on how we use those prepositions. Linguists distinguish between deictic and intrinsic place-identifications (cf. e.g. Garnham 1989). Deictic place-identifications use the reference frame of the viewer to give the location of one object with respect to the location of another. One object functions as a landmark and the viewer's own reference frame is used to say where the other object is with respect to that landmark. So, for example, I might say that my pen is to the left of the computer. I use my own right and left in giving that place-identification, not the right or left of any other person or object, even though the pen and the computer may both be on my right, in effect, the viewer's own egocentric frame is projected onto the landmark object. In contrast, intrinsic spatial relations use the axes of another landmark object than the viewer to specify the location of a target object. So, for example, I might say that the computer is behind Bill and to his left. Here I am not using my own egocentric frame to say where the thing is, but rather using a set of axes centred on Bill. Of course, other objects than humans can sustain such a set of axes. For example, you might talk about what is in front of a car, or to the right of a chair. But not all objects will sustain all the usual prepositions: there is no saying what is the right or left of a golfball, for example. We could, though, make ad hoc stipulations, and in general, in a conversation

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in which reference is being made to particular locations using the basic spatial prepositions, setting up the frame of reference is a collaborative affair between speakers. You could accept that the simple spatial prepositions are used in connection with axes centred on other people, but still think that there is something basic about the use of these prepositions in connection with the thinker's own axes. This is one of the fundamental problems about our understanding of spatial concepts. The problem is: how can you make sense of the use of egocentric spatial terms in connection with an intrinsic frame of reference centred on an object other than yourself? This problem is formally analogous to the problem of other minds. Terms for mental states are used with just the same meanings in connection with different people; words for mental states have the same meanings whoever they are being applied to. Nevertheless, there is something basic about their use in connection with the first person. The problem is to understand how both points can be correct: how the words can be used in just the same way in the first person and in the third person, yet the firstperson use be basic. Similarly, we have to understand how the spatial prepositions can be used in just the same way in connection with different reference frames, while there is something basic about their use in connection with the thinker's own axes. Or again, there is a formally similar point to be made about time. Observational concepts such as 'red' or 'square' can be applied univocally to objects as they are at any time, past or future. But there is nonetheless something basic about the use of such concepts in present-tense propositions. Again, the problem is to understand how the terms can be used univocally in all contexts while a distinguished context is acknowledged to be basic. You might point out that ordinary vision can itself have a spatial content that has to be characterized using deictic or intrinsic spatial notions: for example, you may simply see that someone is standing in front of a train or to the right of a table. In a series of papers, Gordon Logan (1994, 1995, Logan and Sadler 1996) has argued that visual attention is needed to set up deictic frames of reference. To verify the deictic statement, 'A is on the right of B', you must visually select B as reference object, and exercise the visual skill of projecting your own egocentric axes onto B. This is an attentional skill, which involves the selection of the reference object and selection of which axes to project onto it. Similarly, canonical verification of statements using intrinsic frames of reference will involve visual selection of the reference object, and visual selection of the intrinsic axes of the thing. This again is the exercise of an attentional skill. But the exercise of this skill of visual attention depends on having the background, basic egocentric frame in which the initial locations of the relevant target and landmark

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objects are given; otherwise you could not set up the deictic or intrinsic frames at all. If we accept that the spatial prepositions are first explained and understood in connection with the basic egocentric frame of reference, the 'unseen' frame Wittgenstein talked about (cf. Chapter 3, section 1 above), then we need to know how it is that those very same prepositions can be used in the very same senses in connection with other frames of reference. You might try to appeal to an imaginative capacity that we have, to project yourself into the perspective of the other object whose axes are being used to set up the frame of reference. And in fact it is not implausible to suppose that we have some such capacity: if I am trying to imagine how the room looks to you, for example, I may well try to put myself in your place, as it were, and to determine the egocentric locations and spatial relations of objects from that perspective. This is the capacity for spatial deep decentring that I described in Chapter 9, section 3. So it might be said that this imaginative capacity is what allows one to understand the spatial prepositions as having just the same meanings, whatever the frame of reference. In effect, the suggestion is, what we have is not just the basic frame of reference but the capacity to recentre that frame onto another perspective. The difficulty is that this recentring is always recentring to another location, and that location has to be identified using the subject's basic frame of reference. This is particularly striking when you consider the case in which you are using an intrinsic frame of reference centred on another person, who is in turn able to use the spatial prepositions to describe the surroundings. You have not managed to understand the spatial prepositions in the same way that the other person is using them, even though the other person is trying to use the same frame of reference. On the proof-theoretic account, the hard facts about the spatial world relate to the possibility of observation, and any kind of spatial reasoning has to be justified by being shown to be a way of getting at the hard facts about what could or could not be observed. Or we could have a pragmatist version of the view, on which the hard facts about the world all relate to the possibility of action, and any navigational system has to be justified by its conservatively extending the capacities of the animal to act in response to perception. This may be the right theoretical view of some animal navigation systems. For example, consider the case of the navigating rat. Any navigational system the rat uses may be justified as being a conservative extension of its basic spatial observations. What the system has to do, and all it has to do, is predict just the observations the rat will have on pursuing one or another trajectory through its environment. There is no reason to suppose that the rat can be credited with anything other than the kind of

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picture of his environment that the verificationist or pragmatist describes; all there is to the world, for the rat, is the perceptions or actions it affords. For us, though, there is a much stronger sense in which we can grasp the existence of a space not centred on oneself: different speakers all understand the spatial prepositions in the same way, even if they are each using them in connection with their own basic frames of reference, and we have to acknowledge this commensurability of meaning across subjects. The problem with the proof-theoretic account of our grasp of the basic spatial frame of reference, then, is that it leads to a kind of solipsism: you cannot properly understand how the spatial prepositions can be used in connection with other frames of reference, in that in particular, you cannot grasp the meanings that other people give the spatial prepositions in connection with their frames of reference.

11 Indeterminacy and Inscrutability 1. Inscrutability of Terms In Word and Object, Quine articulated the thesis of indeterminacy of translation: that consistently with all the evidence, different, indeed incompatible, translation manuals could be set up for translating from a foreign language into the home tongue, and there be no fact of the matter to the effect that one rather than any of the other translation manuals is correct. To state the thesis, there has to be some view as to the database to which the translation manuals are responsible, and Quine introduced the notion of 'stimulus meaning' to be as explicit as possible about what the database contains: We may begin by defining the affirmative stimulus meaning of a sentence such as 'Gavagai', for a given speaker, as the class of all the stimulations (hence evolving ocular irradiation patterns between properly timed blindfoldings) that would prompt his assent. More explicitly ... a stimulation a belongs to the affirmative stimulus meaning of a sentence S for a given speaker if and only if there is a stimulation a' such that if the speaker were given a', then were asked S, then were given o, and then were asked S again, he would dissent the first time and assent the second. We may define the negative stimulus meaning similarly with 'assent' and 'dissent' interchanged, and the define the stimulus meaning as the ordered pair of the two. (Quine 1960: 32-3)

Quine continues: Stimulus meaning ... may be properly looked upon ... as the objective reality that the linguist has to probe when he undertakes radical translation. For the stimulus meaning of an occasion sentence is by definition the native's total battery of present dispositions to be prompted to assent to or to dissent from the sentence; and these dispositions are just what the linguist has to sample and estimate. (Quine 1960: 39)

'Gavagai' was Quine's example of an observation sentence; that is, roughly, a complete sentence, in that an utterance of it can be assigned a truthvalue, but that difference utterances of the sentence might have different truth-values, and there is widespread agreement through the community

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on which occasions to assent to the query, 'Gavagai?'; the notion of an observation sentence is more complicated than this quick account acknowledges, but the complications do not, so far as I can see, matter for present purposes (Quine 1960:40-6). The sentence 'Gavagai' has the same stimulus meaning as the English sentence 'Rabbit'; it is, as we might say, a cry with which rabbits are greeted. So far, according to Quine, there is no such thing as reference involved in the use of the sentence 'Gavagai'. For us to discern reference in the foreigner's use of a term, it is not enough for there to be its use as a oneword sentence with a definite stimulus meaning. The term also has to interact with what Quine calls the 'various auxiliaries to objective reference': articles and pronouns, singular and plural, the copula and the identity predicate. In particular, for a subject to be translated as using a term as a referring term, the subject has to be discerned to be able to answer such questions as 'Is this the same F as that?', 'Is this the same F I encountered yesterday or a different one?', and so on. Merely using the sentence 'Gavagai' as having a particular stimulus meaning does not yet imply that its use has been linked up to these auxiliaries to singular reference. Moreover, from the standpoint of the translator, there will be different ways in which the auxiliaries to singular reference can be seen as operating in the foreign language. As a consequence of this, Quine draws his conclusion of the inscrutability of reference: Stimulus synonymy of the occasion sentences 'Gavagai' and 'Rabbit' does not even guarantee that 'gavagai' and 'rabbit' are coextensive terms, terms true of the same things. Who knows but what the objects to which this term applies are not rabbits after all, but mere stages, or brief temporal segments, of rabbits? In either event the stimulus situations that prompt assent to 'Gavagai' would be the same as for 'Rabbit'. Or perhaps the objects to which 'gavagai' applies are all and sundry undetached parts of rabbits; again the stimulus meaning would register no difference. (Quine 1960: 51-2)

You might suggest that this shows only that something has been missed out in the definition of 'stimulus meaning'; we ought to be able to resolve the issue about the translation of the term 'gavagai', by looking closely enough at the situations in which it is used. Quine's response is as follows: Does it seem that the imagined indecision between rabbits, stages of rabbits, integral parts of rabbits, the rabbit fusion, and rabbithood must be due merely to some special fault in our formulation of stimulus meaning, and that it should be resoluble by a little supplementary pointing and questioning? Consider, then, how. Point to a rabbit and you have pointed to a stage of a rabbit, to an integral part of a rabbit, to the rabbit fusion, and to where rabbithood is manifested. Point to an

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integral part of a rabbit and you have pointed again to the remaining four sorts of things, and so on around. Nothing not distinguished in stimulus meaning itself is to be distinguished by pointing, unless the pointing is accompanied by questions of identity and diversity: 'Is this the same gavagai as that?' 'Do we have here one gavagai or two?'. Such questioning requires of the linguist a command of the native language far beyond anything we have as yet seen how to account for. We cannot even say what native locutions are to count as analogues of terms as we know them, much less equate them with ours term for term, except as we have also decided what native devices to view as doing in their devious ways the work of our own various auxiliaries to objective reference: our articles and pronouns, our singular and plural, our copula, our identity predicate. The whole apparatus is interdependent, and the very notion of term is as provincial to our culture as are those associated devices. The native may achieve the same net effects through linguistic structures so different that any eventual construing of our devices in the native language and vice versa can prove unnatural and largely arbitrary... Yet. the net effects, the occasion sentences and not the terms, can match up in point of stimulus meanings as well as ever for all that. Occasion sentences and stimulus meaning are general coin; terms and reference are local to our conceptual scheme. (Quine 1960: 53)

The point Quine is making here is that there are no hard facts about which of the foreign constructions to translate by means of the English apparatus of individuation; so long as we translate so as to preserve stimulus meanings, there is no further fact of the matter about what to translate as a singular term and what as a plural, what: to translate as the sign of identity and what to translate as a mere equivalence, and so on. As he puts it: hypotheses need thinking up, and the typical case of thinking up is the case where the linguist apprehends a parallelism in function between some component fragment of a translated whole native sentence and some component word of a translation of the sentence. Only in some such way can we account for anyone ever thinking to translate a native locution radically into English as a plural ending, or as the identity predicate'=', or as a categorical copula, or as any other part of our domestic apparatus of objective reference. It is only by such outright projection of prior linguistic habits that the linguist can find general terms in the native language at all, or having found them, match them with his own; stimulus meanings never suffice to determine even what words are terms, if any, much less what terms are coextensive. (Quine 1960: 70)

From this point Quine draws the conclusion of the inscrutability of reference: We could equate a native expression with any of the disparate English terms 'rabbit', 'rabbit stage', 'undetached rabbit part', etc., and still, by compensatorily juggling the translation of numerical identity and associated particles, preserve conformity to stimulus meanings of occasion sentences. (Quine 1960: 54)

The striking conclusion is that there is no fact of the matter as to what is

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referred to by the use of a term such as 'gavagai': it can be interpreted as referring to any of the above candidates, because by compensating changes in how we translate the apparatus of individuation, we can always preserve stimulus meaning. Similarly, there is no fact of the matter as to what is being referred to by our own term, 'rabbit'. The crucial point here is that reference to objects is not, on Quine's account, the fundamental point of contact between language and the world. The fundamental point of contact is rather between the observation sentence and the patterns of ocular irradiation which prompt assent to the sentence. Reference is a more sophisticated phenomenon, involving interaction between the observation sentences and the apparatus of individuation; and there is no uniquely correct answer to the question how the foreigner's apparatus of individuation should be translated into our own language (see Hylton 2000 for an instructive exegesis of Quine on this point).

2. Attention and Stimulus Meaning As will be evident, the whole thrust of Quine's position here is that the hard facts about meaning—the facts about stimulus meaning—can be characterized prior to consideration of the facts about what refers to what. Once that work of positioning is done, the dramatic thesis of the inscrutability of reference follows merely as an illustration of the main point. But is the main point correct? Can the facts about stimulus meaning be characterized prior to consideration of what refers to what? Suppose we begin with the question whether the stimulus meaning of a sentence can be characterized prior to considering the direction of the subject's attention. After all, patterns of ocular irradiation are all very well, but if I simply do not notice the relevant part of the scene I will not be in a position to answer your questions about the scene correctly, even if I have suitable patterns of ocular irradiation. Here is Quine's one attempt to address the point: In general the ocular irradiation patterns are best conceived in their spatial entirety. For there are examples such as 'Fine weather' which, unlike 'Rabbit' are not keyed to any readily segregated fragments of the scene. Also there are all those rabbit-free patterns that are wanted as prompting dissent from 'Rabbit'. And as for patterns wanted as prompting assent to 'Rabbit', whole scenes will still serve better than selected portions might; for the difference between center and periphery, which is such an important determinant of visual attention, is then automatically allowed for. Total ocular irradiation patterns that differ in centering differ also in limits, and so are simply different patterns. One that shows the rabbit too

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peripherally simply will not be one that prompts assent to 'Gavagai' or 'Rabbit'. (Quine 1960: 32)

This is, of course, wholly inadequate as an attempt to cope with the impact of variation in attention on stimulus meaning. It is a fact of common experience that something can be centred on the fovea and yet not noticed by the subject; we have the expression 'staring me in the face' for just the situation in which you are looking right at the object but do not notice its presence. And as I remarked in Chapter 1, the existence of covert shifts of attention, in which attention shifts without any movement of the eyes, head, or body, has been known at least since Helmholtz 1866/1925. For that situation too we have an expression, looking at it out of the corner of my eye'. Now each of these phenomena independently is capable of torpedoing the intended effect of Quine's definition of stimulus meaning. If I have a rabbit right in front of me, but simply do not notice it, despite having the right pattern of ocular irradiation, then I will not assent to 'Gavagai'. On other occasions, with the same pattern of ocular irradiation, I will assent to 'Gavagai', because I have noticed the thing. So the meaning of 'Gavagai' cannot be characterized simply by listing the patterns of ocular irradiation that will prompt assent to or dissent from the sentence. What prompts assent or dissent is visual attention applied to the input processed as a result of ocular irradiation. Similarly, I will not always dissent from 'Gavagai' if my pattern of ocular irradiation presents a rabbit in the periphery; if I am currently attending to the periphery of my visual field then I will assent to the query. Quine has a principled objection to any such appeal to the operation of visual attention: A visual stimulation is perhaps best identified, for present purposes, with the pattern of chromatic irradiation of the eye. To look deep into the subject's head would be inappropriate even if feasible, for we want to keep clear of his idiosyncratic neural routings or private history of habit formation. We are after his socially inculcated linguistic usage, hence his responses to conditions normally subject to social assessment... Ocular irradiation is intersubjectively checked to some degree by society and linguist alike, by making allowances for the speaker's orientation and the relative disposition of objects. (Quine 1960: 31)

But this plainly gives no particular reason to resist the explicit appeal to visual attention in defining 'stimulus meaning', as opposed to staying with mere patterns of irradiation. Notice to begin with that there is no suggestion in Quine that; ordinarily, speakers directly inspect one another's patterns of irradiation; it is only that there is 'in effect' such checking, by 'making allowances for the speaker's orientation and the relative disposition of objects'. An appeal to visual attention does indeed look 'deep

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into the subject's head', well beyond the pattern of hits on the nerveendings in the retina. But nonetheless, we do 'in effect' intersubjectively check the direction of each other's attention by taking into account each other's interests and what is salient in the context. And there can be no good reason to keep clear of 'idiosyncratic neural routings or private history of habit formation'. These will certainly be involved as determinants of what the subject will or will not attend to—what I find arresting you might pass over without noticing—but what matters from the point of view of meaning is what the upshot is of the subject's visual attention, given that the subject does attend to this or that aspect of the scene. Is the subject's attention not allocated to objects? And if the subject is attending to the objects in the scene, surely we can answer the question 'To which objects is the subject attending?'. And the answer we give to this question will be a contribution to characterizing the hard facts about meaning. We could interpret Quine as responding to some such idea when he says, in a passage I have already quoted: 'Point to a rabbit and you have pointed to a stage of a rabbit, to an integral part of a rabbit, to a rabbit fusion, and to where rabbithood is manifested'(Quine 1960: 52). The suggestion would be that visual attention is only ever allocated to places, rather than to objects, so that we could accommodate spatial attention within a revised definition of stimulus meaning yet still find an inscrutability in reference. There is no particular reason, though, why we should suppose that the allocation of visual attention to places is unproblematic when characterizing the hard facts about meaning, but that there is something problematic about the allocation of visual attention to objects. Why let in places but not objects? Of course there is such a thing as spatial attention, and as we saw in Chapter 2, spatial attention may play a basic role in solving the Binding Problem, and so making perception of objects possible. And, as I argued in Chapters 1-3, location may by being one of the binding parameters for an object provide the way in which the object is identified in conscious attention to it, when we want to answer questions about the object or act with respect to it. But there is no reason to think that location is the only binding parameter involved; indeed, there surely are further principles of binding involved in object perception (cf. Prinzmetal 1995). Anyway, if for some reason we were restricted to considering only spatial aspects of visual attention, the whole attempt to give a definition of stimulus meaning would be blocked at the outset. For it would be possible for a subject to have a particular pattern of ocular irradiation, to be attending to a particular place, but simply not to have noticed the object at that place. This is indeed the case of which we would ordinarily say, 'The thing was staring me in the face and I didn't see it'. In another case, the subject

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might have the same pattern of ocular irradiation, attend to the place, and discern the object there. There is evidently no answer to the question whether that pattern of ocular irradiation, together with visual attention to a particular place, would be in the affirmative stimulus meaning of the relevant observation sentence. The question has turned out to be ill-posed; it could not be answered as it stands. So we would have lost Quine's way of saying what the hard facts about meaning are. It might be argued that for attention to be allocated to an object, the subject must grasp and be exercising a relevant sortal concept. So we cannot take the facts about attention into account without presupposing that we know which sortal concepts the subject has at his disposal. But, this response runs, we were trying to find the foundations for ascription of a particular set of concepts to the subject. This kind of response is not as sympathetic to Quine as it might at first seem. For the point we have reached is that there is no way to state the hard facts about meaning without appealing to facts about visual attention. So if the appeal to visual attention has to be blocked, because it involves appeal to the subject's grasp of concepts, then Quine's project has to abandoned; there is no way of stating the hard facts about meaning. Actually, though, it does not sound right to say that visual attention to an object demands that you grasp the relevant sortal concept. As we saw in Chapter 4, sortal concepts are indeed typically involved in the orientation of attention: if I want you to look specifically at some aspect of the passing show, it will often be much the best way to orient your visual attention to use a sortal concept together with some kind of spatial indicator, whether verbal or by pointing, to orient your attention onto the right thing. But I do not need to know the sort of the object in question in order to be attending to it. You can have got it quite wrong about what sort of thing is there, but still succeed in drawing my attention to it by using a sortal concept that does not apply to the object, as when you say, 'Look at that clock!' and I say, 'It's not a clock, it's a sundial'. And my having my attention fixed on just that thing does not depend on my having the relevant sortal concept myself. Never having seen a sundial, and not even having the conception of such a thing, my attention may nonetheless be arrested by the sight of one; and it may be unquestionable that it is to the sundial that I am attending. I developed that point at much more length in Chapter 4. The present implication is that the allocation of visual attention to objects is a more primitive phenomenon than the application of sortal concepts to objects. Could we, without appealing to the subject's grasp of the relevant sortal concepts, distinguish between the case in which the subject is attending to a temporal stage of a rabbit and the case in which the subject is attending to a rabbit? It seems evident that we can do this. The subject attending to a

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temporal stage will simply stop attending at a certain point, when the stage has reached its end. In contrast, the subject focusing on a rabbit will keep on, even after the stage has terminated. Is there any distinction between visually attending to an undetached rabbit part and visually attending to the entire rabbit? Again, the question is no sooner asked than it is evident what the answer is. The subject visually attending only to the undetached rabbit part, and ignoring the rest of the rabbit, will notice blood only on the rabbit part and will not notice blood elsewhere on the rabbit; the subject attending to the whole rabbit will notice a sufficient quantity of blood anywhere on the thing. The subject attending to the rabbit part will be poised to act only on the part; the subject attending to the whole rabbit will not yet be able to act with respect specifically on any of the parts of the rabbit, but only on the rabbit as a whole. If the two subjects both fire a gun at the rabbit, it will be chance if the first one hits anything other than the particular undetached part, whereas it will be chance that the second one hits some particular part rather than any other part of the rabbit. And so on. The distinctions which Quine finds inscrutable are in fact all available at the level of conscious visual attention. This is a level more primitive than the level at which we have applications of concepts to objects. And as we have seen, Quine can hardly evade appeal to this level in his characterization of the hard facts about meaning; without it, the appeal to stimulus meaning can do no work. Finally, though this is not a point directly addressed in Quine's discussion at all, the notion of visual attention that we need here is the notion of conscious visual attention. Suppose, for example, that we have someone blindsighted, with a rabbit momentarily frozen in the blind field. We query the subject, 'Gavagai?'. It is in principle possible—that is, it is possible, consistently with this being unconscious visual stimulation—that the subject manages, at the level of visual information-processing, to attend sufficiently to be able to answer affirmatively. So the subject might find himself assenting to 'Gavagai?' without any conscious awareness of a rabbit. But this could not be the general case. Suppose that this happened more generally. Suppose that, without anyone having any glimmering as to how this came about, our visual systems, at some level remote from consciousness, became attuned to the presence of certain items in our surroundings— suppose we call them 'spooks'. Then we might find that we could achieve intersubjective agreement on when to assent to 'Spooks!' on the basis of visual information, without any of us ever having experienced these things. But this would evidently be a case in which none of us had the slightest idea what we were talking about. The hard facts about meaning are hard facts about our knowledge of meaning, and our knowledge of meaning depends on our capacities specifically for conscious attention to objects.

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3. Davidson on Inscrutability The point I have been emphasizing is that knowledge of the reference of a demonstrative is provided by conscious attention to the object referred to. With Quine, Davidson objects to any such idea. Davidson writes: The crucial point on which I am with Quine might be put: all the evidence for or against a theory of truth (interpretation, translation) comes in the form of facts about what events or situations in the world cause, or would cause, speakers to assent to, or dissent from, each sentence in the speaker's repertoire. (Davidson 1984a:230)

On Davidson's picture, the notion of reference makes no contact with evidence except by way of yielding theorems of the truth-theory which fit with our assent/dissent behaviour. As Davidson puts it, We don't need the concept of reference; neither do we need reference itself, whatever that may be. For if there is one way of assigning entities to expressions... that yields acceptable results with respect to the truth conditions of sentences, there will be endless other ways that do so as well. There is no reason, then, to call any one of these semantical relations 'reference'. (Davidson 1984b: 224)

On this picture, the axioms of the theory are simply a way of generating appropriate T-sentences—that is, T-sentences with the right assent/dissent dispositions. Like Quine, Davidson sees the striking implication of his view: that there is no uniquely correct account to be given of the reference of a term. This is not a paradox, but simply an illustration of their view at work. Suppose, for example, we are giving a statement of the references of the terms in a language containing the name 'Wilt' and the predicate 'is tall'. Davidson says: suppose that very object has one and only one shadow... On a first theory, we take the name 'Wilt' to refer to Wilt and the predicate 'is tall' to refer to tall things; on the second theory, we take 'Wilt' to refer to the shadow of Wilt and 'is tall' to refer to the shadows of tall things. The first theory tells us that the sentence 'Wilt is tall' is true if and only if Wilt is tall; the second theory tells us that 'Wilt is tall' is true if and only if the shadow of Wilt is the shadow of a tall thing. The truth conditions are clearly equivalent. If one does not mind speaking of facts, one might say that the same fact makes the sentence true in both cases. (Davidson 1984a: 230)

(Davidson remarks that for the example to work properly, everything must be, as well as have, a shadow; like him, I will not labour this complication.) Of course, consciously attending to Wilt is a quite different thing from consciously attending to Wilt's shadow. So why should we take seriously the interpretation of 'Wilt' as referring to Wilt's shadow? Suppose that the

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speakers of the language, when verifying propositions about Wilt or when acting on Wilt, do so by verifying a judgement of the form, 'That man is Wilt', and they consciously attend to the man rather than the shadow for the purposes of verification and action. Is there a serious alternative to the idea that they are referring to the man rather than to the shadow? There are two moves open to Davidson at this point. One is to insist that the indeterminacy afflicts the ascription of conscious attention to subjects. You might argue that there is no saying whether the speaker is consciously attending to Wilt rather than to Wilt's shadow. But that does not seem to be a starter. As Davidson himself sets things up, Wilt's shadow might not even be visible at the time at which the subject is consciously attending to Wilt. We need not pursue the idea that you might be consciously visually attending to something that you cannot see. The other move open to Davidson is to ask why we take it that knowledge of the reference of a demonstrative is provided by conscious attention to the object referred to. On this account, it would be an equally good theory to say that knowledge of the reference of a demonstrative is provided by conscious attention to the object of which the thing referred to is a shadow. I think that this is the move Davidson would make. It does not, on the face of it, seem very promising. Davidson does consider the idea that we might appeal to causal theories of reference to refute the idea that reference is inscrutable, and what he says is that while we can indeed have one theory that appeals to a causal relation C that holds between 'Wilt' and Wilt, but not between the name and Wilt's shadow, we could by the above argument have an equally legitimate theory of reference that appeals to a relation C, that holds between 'Wilt' and the shadow of the cause of the use of that name. By the above permutation argument, this will be an equally legitimate theory of reference, because it will predict just the same assent/dissent behaviour by speakers. This does not seem very promising either. The only reason Davidson's move seems even statable is that there is, after all, some obscurity about why causal connections have the role of fixing reference. If a causal chain between the name and the object fixes the reference of the name, that implies that we have a way of setting standards of correctness for the use of the term. Of course, the causal chain may of itself be a causal factor underlying the use that is made of the term. But the mere fact that it is a causal factor does not of itself mean that it has a role to play in setting standards of rightness and wrongness. Why causal chains should play such a role was not explained in Kripke's (1972) account. The fundamental issue of just how it comes about that we have here not merely a pattern of causes and effects, but uses of language or thought which can be right or wrong, is simply not addressed.

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The appeal to conscious attention to the object as fixing the reference of a demonstrative is consistent with acknowledging the role of causal chains in reference. For it is plausible that to be consciously attending to an object, the object must be causally affecting you. On a relational view of conscious attention, what the object causes will not be the state of conscious attention, for the object is a constituent of the state of conscious attention (cf. Snowdon 1980-1). But for there to be conscious attention to the object, it may still be demanded that the object be causing some sub-personal state in you; in particular, that the visual information-processing with which conscious attention liaises must be the effect of the object (see Chapter 1 for discussion of the liaison here). I think we can understand the role of the causal chain better, though, if we see it as a concomitant of conscious attention to the object, rather than as being directly what constitutes reference. The thesis is that conscious attention to the object is what sets the norms for the pattern of use that we make of the demonstrative; in particular, conscious attention to the object is what sets the norms for the recruitment of visual information-processing to enable us to answer questions about the object or to act on the object. It is the direction of conscious attention to this object or to that which sets the standards by which the informationprocessing that swings into play is to be assessed as successful or not. This phenomenon is far wider than merely our understanding of demonstratives. Conscious attention is implicated in action and investigation of objects that need not involve conceptual thought. If I am trying to put a thread through the eye of a needle, I may be concentrating quite fiercely, on the needle and the thread, but the activity itself need not involve conceptual thought at all. Various visual information-processing procedures are swinging into play as I try to complete the task, and the target set for those information-processing procedures is partly defined by the direction of my conscious attention, onto the thread and the needle: it is that direction of conscious attention that defined what the objects are that have to be dealt with by this information-processing. If the thread goes into another object, or I push something else into the eye of the needle, that counts as error—clumsiness or accident—because of the way in which the target of the exercise has been defined. You might hold that a Davidsonian approach is applicable even here. To vary his example a bit, you might say that in such a case, the objective of the information-processing procedures, as defined by conscious attention, is not to get that thread through that needle, but rather, to get the shadow of the thread to which I am consciously attending through the shadow of the needle to which I am consciously attending. Of course, as before, those shadows need not be visible to me and it may not have occurred to me that

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the thread and needle have shadows. This picture of threading a needle is flatly in conflict with our ordinary picture of our objectives in action, rather than simply being a notational variant of our ordinary picture. If I am accused of clumsiness or failure in my attempts to thread the needle, it would be a retort from very far outside our ordinary comprehension if someone were to claim that his visuomotor skills had in fact performed perfectly, because the shadow of the thread to which he had been attending had actually got through the shadow of the needle to which he had been attending. Of course, you can have a kind of Zen procedure, in which you have one objective but try to achieve it by trying to achieve another, perhaps inconsistent with your real objective—so you may know that to hit the target, you have to aim somewhat above it. Similarly, someone who wants the shadow of the thread to connect with the shadow of the needle might try to achieve that objective by trying to get the thread through the needle. But that is not the case we are considering here. In the case that presently concerns us, there is no such involvement of conceptual thought. We are simply dealing with someone trying to get the thread through the eye of the needle, by consciously attending to the thread and the needle. Given that this is all of the relevant story about the subject, the result of applying Davidson's idea here would be that we should say that success or failure on the part of this subject's visuomotor processing depends entirely on whether the shadow of the thread connects with the shadow of the needle; although, as I have said, the subject need not know that either shadow exists. This idea is certainly very far from our ordinary conception of visuomotor proficiency. Davidson does not himself apply his idea to the non-conceptual cases, such as the needle and the thread. Applied to the role of conscious attention to objects in conceptual thought, his idea is that conscious attention can be setting the objectives for the use of information-processing procedures to verify propositions, or to act on the basis of propositions about the object, as follows: the objective of the information-processing procedures is to yield information true of the shadow of the object to which you are consciously attending, and to allow you to act on the shadow of the object to which you are consciously attending. This does not seem at all persuasive, since those information-processors will typically carry no information whatever about that shadow, since it need not even be visible. The situation is masked in Davidson's example, because he is also considering an interpretation of the subject on which the predicates that the subject uses are all of the form, 'x is the shadow of an object which is F'. But once we get this into view, it appears that taking Davidson's view seriously would also mean reinterpreting the content of visual information-

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processing. If we were to explain how visual information-processing could put us into a position to answer questions about whether a shadow is the shadow of an object which is F, we would have to interpret the information-processing as relating to the things of which the things we see are shadows. But while you can occasionally work out something about what a man is like from looking at his shadow, this is typically a conceptual inference; what we get from visual information-processing is first and foremost information about the things we see, and any information about the things of which they are shadows is supplementary to that. Denying this would leave it obscure how attending to a thread and needle could possibly help you to put the thread through the needle. If you really think that visual processing primarily relates to the characteristics of the things of which you are seeing the shadows, the last thing you ought to be doing is looking directly at the thread and needle in order to get one through the other; you ought rather to be trying to find things of which they are the shadows, and looking at them. The reason for these bizarre implications of the view Davidson is recommending is that it is just a mistake to think that the only level at which we can discern norms of language-use is at the level of the whole sentence. The fundamental point of contact between language and the world is not between the sentence and the patterns of stimulation which cause assent or dissent; the fundamental point of contact is rather between the demonstrative and the conscious attention to the object which sets the standards of right and wrong for the information-processing that swings into play to allow you to verify or act on the basis of propositions about the object.

4. Predication and Singular Reference So far I have been stressing the opposition between a view such as Quine's or Davidson's, on which the phenomena with which characterization of meaning deals are at the level of stimulations which command assent to sentences, and a view on which the knowledge of reference provided by conscious attention to objects has a fundamental role to play in determining standards of right and wrong. Evans 1985a sets out a response to Quine's remarks on the interpretation of the term 'gavagai'; how does it bear on this overarching issue? For our purposes, there are two types of point that Evans is making about the constraints on an interpretation of a singular term, which have to do with the kinds of predicates that we find in the language. First, suppose we consider simple ascriptions of colour to objects, such as 'White rabbit!'. To recognize whether there is a white rabbit present, you have to have some

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sensitivity, in your verifications, to the boundaries of rabbits, to when we are dealing with one rabbit and when we are dealing with two. It is not enough, for there to be a white rabbit present, that there be a rabbit present and that there be something white present, since otherwise a brown rabbit in the snow would prompt assent to 'White rabbit!'. Nor is it enough that there be a white rabbit part present, since otherwise a brown rabbit with a white foot would count. Nor, finally, is it enough that there should be a rabbit-sized quantity of white rabbit parts present, since otherwise, to use Evans's memorable example, assent would be prompted by a group of brown rabbits so organized that their white tails are contiguous. The assent-conditions of 'White rabbit!' just do involve a sensitivity to the boundaries of a single rabbit. This means that translations of 'Gavagai' as 'Rabbiteth!', 'Rabbithood is made locally manifest!' and 'The rabbit fusion has a local component!' can be ruled out, for the assent-conditions of these propositions do not involve any such sensitivity to the distinction between one rabbit and two. Evans's second type of point is this. The other examples of indeterminacy which Quine gave had to do with the possibility of interpreting 'gavagai' as meaning 'undetached rabbit part' or 'undetached rabbit stage'. But the problem with these translations emerges again when we consider the assent conditions of predications. Suppose we take it that the speaker is referring to undetached rabbit parts in his use of the term. What we will find, Evans points out, is this: 'different parts of the same rabbit are indistinguishable by the predicates of the language' (1985a: 43). It appears that speakers will assent to 'White undetached rabbit part' for one part of the rabbit when and only when they will assent to 'White undetached rabbit part' for another part of the same rabbit. A similar point applies to the interpretation of 'gavagai' as relating to rabbit stages, that different stages of the same rabbit will be indistinguishable by the predicates of the language, at least so far as we can tell from the assent/dissent behaviour of the speakers. These are evidently powerful points, but it is not immediately obvious how to interpret their significance. In particular, is Evans accepting the Quine/Davidson framework, on which the point of contact between language and the world is at the level of the observation sentence and the situations which prompt assent to it? You might read him as aiming to accept that framework, but to show that even within the framework, the scope for variation in the translations of 'gavagai' is less than Quine imagined. Alternatively, is Evans in effect challenging the whole framework, and arguing that the fundamental point of contact between language and the world is at the level of reference? And in that case, his two types of point have to be read as providing restrictions on the reference relation, now

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taken as fundamental, rather than, as by Quine and Davidson, something projected in by the theorist. This puzzle arises because throughout his article, Evans speaks the language of assent/dissent conditions, but his constraint actually cuts little ice if we accept the Quine/Davidson framework. Remember that in this framework, it is only by 'outright projection of prior linguistic habits that the linguist can find general terms in the native language at all' (Quine 1960: 70). In these terms, what Evans is doing is to propose a constraint on the projection of reference onto the target language. There is no 'fact of the matter' about what we are referring to that the constraint can be viewed as aiming to capture. So the constraint cannot be argued for by arguing that only by observing it can we keep faith with the facts about reference; there are no facts about reference with which the constraint might help us keep faith. The constraint is at best a more or less arbitrary restriction on the families of projections we will go in for. While it might seem intuitive enough, Quine and Davidson would quite rightly feel that the thrust of their position had not been challenged at all. Evans's two types of point only really make sense, and we can only do justice to their intuitive force, by locating them in a framework in which the fundamental point of contact between language and reality is seen to include the knowledge of reference provided by conscious attention to objects. In these terms, his proposal amounts to a condition on when it will be right to say that we have conscious attention to this object rather than that. On the one hand, we will say that we have conscious attention to rabbits, rather than to a local component of the rabbit fusion, for example, if the subject correctly applies predicates, such as 'white', on the basis of conscious attention, whose applicability depends on the boundaries of a single rabbit, rather than there merely being a rabbit-sized white local component of the rabbit fusion. And, on the other hand, we will say that we have conscious attention to a rabbit, rather than to an undetached rabbit part, so long as the subject is applying, on the basis of conscious attention, predicates which apply to one undetached rabbit part only if they apply to all undetached parts of the same rabbit. Or, to put it another way, we will say that the subject is consciously attending to an undetached rabbit part if he can, on the basis of conscious attention, apply predicates to that undetached rabbit part while withholding them from other undetached parts of the same rabbit. Put like that, Evans's points can be viewed as putting reasonable, and substantive, constraints on when it is correct to say we have conscious attention to this object rather than that; they are not simply arbitrary constraints on what kinds of projections we will go in for, but elucidations of the character of an independently existing phenomenon, conscious atten-

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tion. There are other, more basic constraints on the ascription of conscious attention, as we have seen: we can look at the subject's capacity to keep track of an object to which he is consciously attending, or to act differentially with respect to that thing, for example, in determining to which object he is consciously attending. These constraints are more basic because they do not yet involve the subject's capacity for conceptual thought at all. But nonetheless, for the case of a subject who is capable of conceptual thought, we can acknowledge the compelling nature of Evans's constraints by viewing them as constraints on the ascription of the conscious attention to objects that provides knowledge of the references of demonstratives, rejecting the Quine/Davidson framework.

5. Underdetermination and Indeterminacy So far I have been discussing the inscrutability of terms, which Quine distinguishes from the indeterminacy of translation. The indeterminacy thesis is that there are different, equally acceptable translation manuals which nonetheless give conflicting translations of one and the same foreign sentence. For the purposes of the indeterminacy thesis, the various translations of the sentence 'Gavagai!' that there are, in parallel with the various translations of the term 'gavagai', do not constitute conflicting interpretations. These are all observation sentences with the same stimulus meaning; in Quine's terms, that is as determinate as translation ever could be. His fundamental argument for indeterminacy is an argument from the underdetermination of physical theory. On the Underdetermination of physical theory, Quine wrote this: conceivably the truths about molecules are only partially determined by any ideal organon of scientific method plus all the truths that can be said in common-sense terms about ordinary things; for in general the simplest possible theory to a given purpose need not be unique. Actually the truths that can be said even in common-sense terms about ordinary things are themselves, in turn, far in excess of any available data. The incompleteness of determination of molecular behaviour by the behaviour of ordinary things is hence only incidental to this more basic indeterminacy: both sorts of events are less than determined by our surface irritations. This remains true even if we include all past, present and future irritations of all the far-flung surfaces of mankind; and probably even if we throw in an in fact unachieved idea organon of scientific method besides. (Quine 1960: 22)

And the argument from Underdetermination to indeterminacy is as follows:

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Insofar as the truth of physical theory is underdetermined by observables, the translation of the foreigner's physical theory is underdetermined by translation of his observation sentences. If our physical theory can vary though all possible observations be fixed, then our translation of his physical theory can vary though our translations of all possible observations on his part be fixed. Our translation of his observation sentences no more fixes our translation of his physical theory than our own possible observations fix our own physical theory. (Quine 1970: 179-80)

However, you might wonder whether this line of thought does not apply also to our talk of medium-sized physical objects. For on Quine's account, our talk of medium-sized physical objects is itself part of a physical theory, provisional like all physical theory: we shall find, as we get on with organizing and adjusting various of the turns of phrase that participate in what pass for affirmations of existence, that certain of these take on key significance in the increasingly systematic structure; and then, reacting in a manner typical of scientific behaviour, we shall come to favor these idioms as the existence affirmations 'strictly so-called'. One could even end up, though we ourselves shall not, by finding that the smoothest and most adequate overall account of the world does not after all accord existence to ordinary physical things, in that refined sense of existence. Such eventual departures from Johnsonian usage could partake of the spirit of science and even of the evolutionary spirit of ordinary language itself. (Quine 1960:4)

If this is correct, then presumably our talk of medium-sized physical objects is, like all physical theory, itself subject to the underdetermination of theory, and consequently the translation even of observation sentences about macroscopic physical things will be subject to indeterminacy. If T1 and T2 are different theories at the level of macroscopic physical objects, and T1 is our ordinary theory which talks about tables and chairs and so on, whereas T2 is a rival theory which talks about some quite different entities, then if we can translate the foreigner as an adherent of T1, we can presumably, with equal right, translate the foreigner as a devotee of T2,. And ultimately, on this account, there will be no fact of the matter as to which theory the foreigner accepts. Indeed, there is no fact, of the matter as to which theory we ourselves accept. There is, though, a puzzle about this. Quine begins Word and Object by arguing, briefly but persuasively, that talk of conscious experiences depends on talk of the medium-sized physical objects of which we have experience: the trouble is that immediate experience simply will not, of itself, cohere as an autonomous domain. References to physical things are largely what hold it together. These references are not just inessential vestiges of the initially inter-

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subjective character of language, capable of being weeded out by devising an artificially subjective language for sense data. Rather they give us our main continuing access to past sense data themselves; for past sense data are mostly gone for good except as commemorated in physical posits. (Quine 1960: 2-3)

The puzzle is: how then can physical objects occupy the status of theoretical posits with respect to our experience? If the experiences themselves are individuated—'held together'—by the physical objects which they are experiences of, then how could we hold the experiences constant and yet vary the macroscopic physical objects we 'posit' to be the objects that those experiences are experiences of? And if that is not possible then there is no question of there being any underdetermination of our ordinary 'theory' of macroscopic physical objects with respect to our experiences of those objects. Moreover, there seems to be no possibility of us finding out that the 'theory' of macroscopic physical objects is itself mistaken, or finding that the best explanation of our current experiences does not involve the postulation of these macroscopic physical objects, does not 'accord existence' to the familiar physical objects. It is evident what Quine must reply to this. He must reply that the underdetermination of theory is not an underdetermination of theory by the experiences we wish to explain, but rather an underdetermination of theory by, centrally, patterns of ocular irradiation. These patterns of ocular irradiation are not 'held together' in any sense by macroscopic physical objects, so it is entirely possible that a given set of ocular irradiation patterns could be explained equally well by many conflicting physical theories, including theories which conflict over which macroscopic objects there are, or even over whether there are any macroscopic objects. This puts a great deal of weight on how the patterns of ocular irradiation are themselves to be characterized, and again it is evident how Quine would proceed here: these patterns have to be characterized in terms of the best physical theories available to us; there really is no alternative to that. At this point, though, we may have secured an underdetermination of talk of macroscopic physical objects by patterns of ocular irradiation, but it is hard to see how there can be any significant underdetermination of physical theory by patterns of ocular irradiation. For the patterns of ocular irradiation have to be described in terms of the physics of the day; how then could they be consistent with some rival to the physics of the day? There is a further problem with this position. Once we have accepted that all physical theory is ultimately responsible to the evolving patterns of ocular irradiation that we undergo, there automatically sets in a certain ossification of physical theory. There now is no escape from the physics presupposed in our description of those patterns of ocular irradiation. All

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subsequent physical theory has to be regarded as responsible to those patterns of ocular irradiation. But then there is no Archimedean point from which the very idea of these patterns of ocular irradiation might be overthrown. This is obviously unacceptable: if this really were to be taken seriously, the potential would be opened for science to fall into a kind of scholasticism in which there is simply proliferation of theory upon theory with no possibility of a radical revision of the whole structure, whether piecemeal or wholesale. The whole trouble here is that the talk of patterns of ocular irradiation itself has theoretical status, and as such is liable to revision; the talk of patterns of ocular irradiation is itself theoretical with respect to our experiences of the world. The very idea that the stimulation of the eyes is responsible for visual experience is itself a hypothesis, albeit a hypothesis for which there is ample confirmation. What allows us to revise the idea of a pattern of ocular irradiation—what makes the idea of such revision intelligible—is the fact that talk of patterns of ocular irradiation is itself theoretical with respect to our experiences of the world. Scientific theorizing can never let go of the idea that it is ultimately our experiences that have to be explained, for only holding on to that idea will hold open the possibility of radical revision of scientific theory, and allow us to resist the collapse into scholasticism. This was, indeed, Quine's own position in Quine 1953b. All causal thinking has to keep a place for the idea of the observer's place in the world, so that reflection is possible on the relation between the observer and the phenomena observed. If, though, we accept that the goal of science is the explanation of experience, and that experience simply 'will not, of itself, cohere as an autonomous domain', then there is a certain a priori character to our ordinary talk of macroscopic physical objects. Certainly we cannot now regard our talk of medium-sized physical objects as a theory liable to revision and subject to underdetermination. Consequently, there will be no question of indeterminacy for the translation of sentences about mediumsized physical objects.

12 Dispositional vs. Categorical I have argued that conscious attention to the relevant object provides one with knowledge of the reference of a perceptual demonstrative. We have looked at extensions of this point to the cases of joint attention and memory demonstratives, and we have looked at the implications of the point for the programmes of Dummett and Quine. I want finally to look further at a point I have emphasized: the role of experience in providing us with our knowledge of the categorical. I begin by setting out, more fully than I have so far, the view that tries to dispense with the idea of appealing to categorical properties and objects: that we can conceive of properties and objects only as complexes of dispositions. I will argue that in fact we cannot eliminate the appeal to categorical properties and objects: our understanding of causation depends on our grasp of categorical properties and objects. However, I have to acknowledge that we do conceive of properties and objects as having dispositional characteristics. So on the one hand, there is our knowledge of categorical properties and objects, and on other hand, there is our knowledge of the complexes of dispositions that are grounded by categorical objects and properties. I will in conclusion look at the relation between these two types of knowledge: between knowledge of the categorical and knowledge of the dispositional. I will argue that our experience of the categorical is what causes and justifies us in taking the world to have the dispositional characteristics that it does, and that this causing and justifying is mediated by the focus of our conscious attention. The view that we have the conception of properties and objects only as complexes of dispositions has been given quite a deep development and defence by Sydney Shoemaker, so I begin by setting out his account.

1. Dispositionalism As I said, although my principal concern is with the role of conscious attention in providing knowledge of the reference of a perceptual demonstrative, I want also, in this chapter, to look at the role of experience in our

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knowledge of properties. Suppose we begin by setting out, for the purpose of contrast, a functionalist view of shape properties: that is, a view on which shape properties are complexes of dispositions. We can contrast this with the kind of view I have been advocating, on which shape properties are the categorical bases of complexes of dispositions. A disposition is an input-output state, a tendency that the thing has to behave in a particular way in particular circumstances. For example, whether something is brittle is a matter of it tending to break when pressure is applied, for something to be striking is for it to be liable to draw notice, and for someone to be drowsy is for him to be liable to fall asleep. The canonical description of a power is: In trigger circumstances C, the object responds in way R. When we describe the property in this way, we say what it is. If we can say what two properties A and B are in this format, then A is identical to B if the replacements for C and R are the same in the two descriptions. Shapes are not input-output states in this sense. The shape of an object is not something that affects the behaviour of the object in a uniform way. The shape of an object is, of course, causally relevant to how the object behaves. But exactly how it affects the behaviour of the object depends on what other properties the object has. For example, something chair-shaped has the capacity to support a seated human, but only if it is the right size, and only if it is made of rigid rather than thoroughly flexible materials. But being chair-shaped matters for supporting a seated human, being about the right size and made of rigid materials is not enough. This suggests that we might think of a shape property as something which affects the causal powers of an object that has it, but does so in a way that depends on just which other properties the object has. For example, being spherical together with being hollow and made of a resilient material will mean that the thing is relatively easy to propel through the air, whereas if it is spherical, solid and made of a dense material it will be harder to get moving but travel for longer. We could put this more formally by saying that a 'conditional power' of an object is something which means that the object will have a certain power if it has certain further properties. The canonical description of a conditional power is: If the object has further properties Q1, . . ., Qn, then the object has power P. And the canonical description of the power P will be in the format already given. In general a shape property, such as the property of being cylindrical, cannot be identified with any one conditional power. Being cylindrical involves having many conditional powers. Nevertheless, a functionalist says, you could still identify being cylindrical with possessing a

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number of conditional powers. This is Sydney Shoemaker's theory of properties in general (Shoemaker 1984a, 1984b). Shoemaker holds that a property is a cluster of conditional powers. He does not hold the converse: that any cluster of powers is a property. To constitute a property, a cluster of conditional powers must have a certain causal unity; not just any haphazard collection of conditional powers will do. A family of conditional powers will constitute a property only if it contains one or more conditional powers which meet the following condition: it is a consequence of causal law that any object which has those conditional powers will also have all the other conditional powers in the family. You might object that the 'further properties' required in specifying a conditional power, or the 'trigger circumstances' or 'responses' involved in specifying a simple power, will need at some point to be categorical properties, so that a wholesale functionalism is not a viable option. But on the face of it, the further properties appealed to may themselves be functionally definable, in the same kind of way. The macroscopic properties of physical objects may in a familiar way be given a simultaneous, higherorder definition. In effect, we could regard the Ramsey sentence for our ordinary 'intuitive physics' of the medium-sized world we experience as giving a simultaneous definition of the properties of physical objects. We could give a similar account of physical objects as complexes of conditional powers. We could think of a physical object as consisting of a collection of tendencies to transmit marks—that is, the effects of impacts upon it—over time, dependent on various particular conditions being met. Or we could amplify this kind of definition to include also tendencies of the object to affect a range of other objects at any one time, in ways depending not only on its initial condition but also on further environmental conditions being met. But on the face of it, there would be no difficulty of principle in articulating such a dispositionalist view of ordinary physical objects. I think it is fair to say that the thrust of Shoemaker 1984a is to contribute to this dispositionalist project, though he does not state the view quite as bluntly as this.

2. The Argument for Dispositionalism In setting out the view of shape properties as families of complex dispositions, Sydney Shoemaker gave the following argument in its favour: 'My reasons for holding this theory of properties are, broadly speaking, epistemological. Only if some causal theory of properties is true, I believe, can it be explained how properties are capable of engaging our knowledge, and our language, in the way they do' (1984b: 214). According to

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Shoemaker, the alternative to supposing that shape properties are families of complex dispositions is to suppose that the identity of properties consists in something logically independent of their causal potentialities. This opens a number of possibilities: (1) It ought to be possible for there to be properties that have no potential whatever for contributing to causal power, so that under no conceivable circumstances will their possession by a thing make any difference to the way the presence of that thing affects other things or the way other things affect it. (2) It ought to be possible for there to be two or more different properties that make, under all possible circumstances, exactly the same contribution to the causal powers of the things that have them. (3) It ought to be possible that the potential of a property for contributing to the production of causal powers might change over time. In consequence of (l)-(3), we have: (4) There would be no way in which a particular property could be picked out so as to have a name attached to it, and even if a name did get attached to a property, it would be impossible for anyone to have any justification for applying the name on subsequent occasions. (Shoemaker 1984b: 214-15) We have to acknowledge that these conclusions are indeed unacceptable. The question is whether they really are implications of the view of shape properties as the categorical grounds of complexes of dispositions. To meet these points, we have to rule out 'absent' properties (1), 'permutated' properties (2), and 'changeable' properties (3). It will be evident from all I have said so far in this book that I think this argument can be dealt with, and that it can be dealt with by appeal to the notion of experience as experience of the categorical. If we think of experience as a relation between the subject and the categorical object or property itself, then the answers to the above arguments are immediate. We know whether the property is present or absent, because we have experience of it, and we do not encounter merely the dispositions that it grounds. We know which categorical property it is that is grounding a particular complex of dispositions possessed by an object, because we have experience of that particular property itself, not just a contact with the dispositions it grounds. And so long as it is that property that we encounter on experiencing the object, we know that there has been no permutation. Of course it is possible to construct sceptical scenarios on which the nature of

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our experience changes in ways undetectable by us; but this general problem of scepticism is not an issue on which the dispositionalist has any advantage. Unless we capitulate to the sceptic, we would ordinarily take it that so long as we are not actually in a sceptical scenario, we do have the right to take it that experience is confronting us with categorical objects and properties. The dispositionalist will undoubtedly feel that this rejoinder is too quick, and may give a kind of 'manifestation' argument in response to it. The proponent of a relational view of experience takes it as evident that experience confronts us with categorical objects and properties. But the dispositionalist will ask: 'What could it be for experience to be confronting us with the categorical? How could the perceiving subject manifest anything more than an encounter with dispositions of the object?' This seems to me a fundamental challenge, and I want to spend the rest of this section articulating it. The point here is not only to consider what arguments are available to the dispositionalist. Even if we think of experience as a relation to the categorical, we have to acknowledge that we do know the dispositional characteristics of things. So we still have to ask in what form we have this knowledge, and how knowledge of the dispositional is related to knowledge of the categorical. So I will in effect be setting out the format in which we may be said to have knowledge of the dispositional, and in section 4 we will look at how it may be related to knowledge of the categorical. To see the force of the dispositionalist's challenge, suppose we begin by asking: 'How does the fact that one perceives an object as having a simple power affect one's behavioural response to it?' Suppose you perceive a cat as ready to pounce, for example. How you react will in part depend on what you make of the pouncing. For example, you might want to take advantage of the relative vulnerability of the cat to outside attack during the pounce. So then you will position yourself ready to take advantage, should the trigger to the pounce appear. In the case of a simple power, then, the behavioural response is conditional on whether one takes the trigger conditions to be met. It may also involve acting to ensure that the trigger conditions are met, or to ensure that they are not met. Suppose now we consider how perception of an object as having a conditional power would affect one's behavioural response to it. What we need is a conditionalization of the account just given of the behavioural response to perception of a simple power. Suppose that you perceive an object as having a power P, conditionally on its further possession of properties Q1, . . ., Qn. Then whether you have the behavioural response to the object which is appropriate to its having the simple power P will be conditional on whether you also know the object to have the properties

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Q!, . . ., Qn. And depending on whether you want the thing to have the power P, you may act to ensure, or to prevent, the thing's having the properties Q 1 , . . . , Q n . Suppose we ask how perception of an object as having a cluster of conditional powers will affect one's behavioural response to it. This will be a matter of having a family of complex conditional behavioural responses of the type just indicated, one for each conditional power in the cluster. That one has grasped the causal unity of the cluster will show up in the causal unity of one's behavioural responses. That is, there will be one or more of the family of responses which are such that if they are activated by perception, all the rest of the responses in the family are activated. There may be a single complex mechanism underlying all that family of behavioural responses. We could give an account of shape perception which has the same general type of structure but which focuses on imagery rather than on action and manipulation. That is, we could have an account which sees the perception as being located in a space of imagistic reasoning. Perception of an object as having a simple power would be a matter of the kinds of imagistic transformation to which one was disposed to subject the image. So, for example, perceiving the cat as ready to pounce would come to this: if you asked yourself, 'What will happen if a mouse appears?', by imagining the appearance of a mouse on the scene, you would follow that up by imagining the cat to leap. This transition would be internal to your imagistic reasoning, it would not be a matter of having your imagery controlled by some explicit verbal reasoning. How would perception of an object as having a conditional power affect the role of the perception in your imagistic reasoning? Here we need a conditionalization of the account just given of perception of a simple power. Suppose that you perceive an object as having a power P, conditionally on its further possession of properties Q1 ..., Qn. What this comes to is that if you perceive it also to have Q 1 ,..., Qn, then you will imagistically manipulate the perception in a way appropriate to its having power P. And even if you do not initially perceive the object to have Q1, . . ., Qn, if you do then make the imagistic transformation of imagining it to have Q 1 ,.. ., Qu, you will then in further imagistic transformations proceed in the way appropriate to the object's having power P. That is, if you imagine the trigger to appear, you will further imagine the response to have been produced. Finally, suppose we ask how perception of a cluster of conditional powers would affect the role of the perception in one's imagistic reasoning. This will be a matter of the perception being related in the way just indicated to a whole family of imagistic transformations, depending on just which further properties one perceived the object to have, or went on to imagine it as

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having. And the causal unity of the cluster of conditional powers would show up in the causal unity of this set of responses in one's imagistic reasoning. That is, if you located the perception thus and so with respect to one subset of the family of imagistic transformations, it would automatically be located appropriately with respect to all the rest of the family of imagistic transformations. Whether we do it by looking at the behavioural implications of the perception, or by looking at the role of the perception in imagistic reasoning, then, it does seem that we can make sense of the idea of perceiving a shape as a family of conditional powers. The problem now is not to find what can be meant by saying that we perceive a shape as a family of conditional powers. There would only be a problem if we thought that perception of shape comes to any more than this; if we thought, for example, that perception of shape is perception of the categorical ground of a family of conditional powers. The problem now is to see what reason there might be for thinking that there must be such a thing as experience of the categorical, and, if such a thing exists, what its relation is to the behavioural dispositions and imaginative reasoning capacities that I have just indicated. In section 3,1 will address the question why we have to think of objects and properties as categorical. In section 4,1 will look at the relation between experience of the categorical and the kinds of behavioural response and imaginative reasoning that I have just indicated. 3. Shoemaker's Puzzle We certainly do not ordinarily operate with the kind of picture of the world that the dispositionalist recommends. Suppose we consider what the dispositionalist must say about such a property as 'being wheel-shaped'. On this view, being wheel-shaped will be a matter of having an enormous number of dispositions to behave in various ways, depending on which other properties the object has. For instance, something wheel-shaped has the disposition to roll along under the weight of a rider, if made of rigid materials, the right size, and suitably installed on a bicycle. The dispositionalist identifies being wheel-shaped with possession of a massive totality of dispositions of this sort. But our ordinary picture is that shapes are the paradigms of categorical properties. We would say that the property of being wheel-shaped is the reason why the object has that totality of dispositions, rather than simply being identical to the totality. You could argue for this view by considering what happens when there is a change in the shape of an object. Suppose, for example, that the wheel of a bicycle gets bent. The whole totality of dispositions that the wheel has is

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affected simultaneously. But how can this happen? How can a totality of dispositions be changed? You could do it by acting on each disposition separately. But the various dispositions do not seem to be affected piecemeal, one by one. And it is hard to see how you could single out some core set of dispositions which are affected first so that changes in them cause changes in the other dispositions. The picture we would ordinarily use is that the shape of the wheel is the causal ground of its having that totality of dispositions. So acting on the shape of the wheel is acting on the causal ground of the totality of dispositions. That is what explains the ability of action on the object to affect all those dispositions simultaneously. Another way to get at the contrast between the dispositionalist's account and our ordinary picture is to recall the example of the square peg and the round hole. Why can't the peg get through the hole? As Putnam pointed out long ago (Putnam 1975), it is quite wrong to look for an explanation of this phenomenon at the level of quantum mechanics: a finely detailed story about the particles constituting the peg and the board is beside the point. We have to look for an explanation at the macroscopic level. And at the macroscopic level, the explanation is this. Because the peg and the board are both made of rigid material, and the length of the side of the peg is the same as the diameter of the hole, the squareness of the peg means that its diagonal is larger than the diameter of the hole, so the peg cannot get through. But what, on the dispositionalist's account, does the appeal to the squareness of the peg come to here? On this account, it is an appeal to a cluster of conditional powers that the peg has. Now these will mostly be irrelevant to the problem at hand. But there is, in particular, the following: one of the cluster of conditional powers is that if the object is rigid, then it will have the power to be unable to get through a hole with the same diameter as the length of its side. So since the object is rigid, it has the power to be unable to get through a hole with the same diameter as the length of its side. That is the explanation of why the peg cannot get through the hole. In effect, we have a virtus dormitiva explanation here. But there is a difference between this virtus dormitiva explanation and the original. Someone who explains the fact that opium puts people to sleep by saying that it has a 'dormitive power' is at any rate saying that the opium has this dispositional characteristic and holding open the possibility of explaining its possession of this disposition by appealing to microstructural features of the opium and human physiology. But in the case of the peg and the hole, we have, on the dispositionalist's account, given a virtus dormitiva explanation and we know already that no deeper explanation in terms of microstructural properties will be forthcoming. That was Putnam's point. Consider now the case of categorical objects. Suppose you pay a nostalgic visit to your old school, and in the corner there is a desk, just as you

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remember it, with, look at that, your initials carved on the lid. Why is that mark there on that desk? The explanation is provided by an appeal to the identity of the object: what explains the mark being there is that this is the very same desk that you carved your initials on all those years ago. And this appeal to identity has causal-explanatory force: it is not just that there is here an unsupported disposition for there to be mark-transmission over time. The sameness of the desk is, we would ordinarily think, the categorical basis of that tendency for mark-transmission over time. You might acknowledge that points such as these do establish that we do not ordinarily think of objects and properties in the way that the dispositionalist advocates, but say that an argument such as Shoemaker's 'epistemological' argument, which I rehearsed in section 2 above, shows that common sense must be mistaken on this point. The trouble with that kind of response is not just that the 'epistemological' argument does not seem sufficiently compelling to force abandonment of common sense. The trouble is rather that the appeal to categorical objects and properties seems to be ineliminable from our picture of the world. We do need the conception of categorical objects and properties, and in fact I think that the simplest way of demonstrating this has been provided by Shoemaker himself. The problem is that in the world as described by the dispositionalist, there is simply not enough to sustain our ordinary talk of objects and causation. So however exactly we do it, it must be possible to find a response to the manifestation argument of the last section, to explain just how it is that our ordinary talk of objects and causation is sustained. I said that the problem is that there is not enough, in the world as described by the dispositionalist, to sustain our ordinary talk of objects and causation. The difficult thing in formulating this problem is to make sure that the dispositionalist is not making some tacit appeal to a rich conception of categorical objects and properties that he officially disavows. To see the shape of the difficulty, suppose we consider a much simpler—and much less attractive—view than dispositionalism, which also aims to subtract from the world the kinds of categorical objects and properties I have indicated. The view I have in mind here is one which analyses objects simply in terms of their actual spatial extensions. A particular physical object, on this account, is no more than an actual area of space, varying in its exact contour over time, from the beginning to the end of the existence of the object. This view is not one which makes appeal to the notion of the object as an 'occupier' of space, using an as yet unexplained notion of 'occupancy'. This view is one which has no place for the notion of the 'matter', something over and above geometrical extension itself, which might be thought to be filling the space. Rather, it attempts to analyse the notion of a physical object in purely geometrical terms. On this view, which we might

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call a 'neo-Cartesian' view, we can represent an object as a set of space-time points in the actual world. Every physical object does have a particular path through the world, from beginning to end of its existence, so we will be able to represent it in this way. The advantage of considering objects as represented simply by sets of actual space-time points is that it helps us make sure that the neo-Cartesian is not illegitimately appealing to richer notions than those to which he is entitled; in particular, the neo-Cartesian is not appealing to any notion of the categorical properties in virtue of which a physical object fills space. Why should we think that there is anything more to a physical object than the neo-Cartesian allows? Just as an exercise, suppose you consider how you might go about refuting this view. I think that there are two immediate lines of objection you might have. One is that it seems possible to argue that there can be different objects in the same place at the same time, if those objects are of different sorts (Wiggins 2001). So, for example, a mass of clay and a statue can occupy the same place at the same time; but they are different objects, since the statue may be destroyed, yet the clay survive. In principle there is no reason why it should not happen that there are objects of different sorts which, as it happens, occupy just the same places, at just the same times, throughout their existences. The neo-Cartesian view would not be able to differentiate such objects, since it would have to represent them by just the same set of spacetime points. And the neo-Cartesian is considering only the actual trajectories of objects, not the routes they might take in other possible worlds, as constituting those objects. The second objection you might immediately raise to the neo-Cartesian view is that it seems to recognize far more objects as physical objects than we ordinarily would. On the face of it, it looks as though any set of spacetime points, however gerrymandered, would be recognized by the neoCartesian as representing a physical object. The neo-Cartesian seems to make the world a much fuller place than it actually is. There are two types of response the neo-Cartesian might make to this second objection. One would be to supplement the account of what a physical object is, with some kind of appeal to causation. For, the neoCartesian might say, the physical objects we ordinarily recognize are no more than particular extensions with particular types of causal significance. What separates the sets of space-time points that do, from the sets of space-time points that do not, represent genuine physical objects is that those which do represent genuine physical objects have a particular type of causal significance. The immediate problem with this kind of reply is that the neo-Cartesian is working with such an impoverished conception of 'physical object' that it is not obvious that there are the materials available for a suitable conception of causation. In particular, objects are being con-

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sidered only as represented by collections of actual space-time points, so we do not yet have the resources to consider what might happen to those 'objects' in other possible worlds. The second type of response the neoCartesian might make would be to appeal to an anthropocentric conception of the difference between the sets of space-time points which do, and those which do not, represent genuine physical things. All there is to the contrast, the neo-Cartesian might say, is that certain sectors of space strike us as being objects, whereas other sectors of space do not strike us as being physical objects. But this seems to get things round the wrong way. It is because some sectors of space are occupied by physical things that they strike us as being occupied by physical things. The distinction is not merely an arbitrary projection by us. So much, then, for our preliminary exercise. Let us now turn, from the neo-Cartesian, to the view of physical objects provided by the dispositionalist, who also aims to subtract categorical objects and properties from the world. The trajectory of a physical object through the world, from beginning to end, is still a matter of places being occupied by it at various times. So, again, we can represent the trajectory of the object by a set of spacetime points. Of course, it is possible for different objects to occupy the same places at the same times, if they are of different sorts: a mass of clay may occupy the same places at the same times as the statue made from the clay. In this kind of case, though, it is always possible for the trajectories of the objects to be different, even if they do not in fact diverge. So for each object, and each possible world, we can consider the set of space-time points occupied by the object in that world. And this seems to give us enough to differentiate the objects; the dispositionalist can meet the analogue of the first objection I raised to the neo-Cartesian. So, the dispositionalist says, we can think of each object as being uniquely specified by the collection of sets of space-time points which the object occupies in each possible world. The advantage of proceeding in this way—representing objects by collections of space-time points for each possible world—is that it protects the dispositionalist from the charge of tacitly appealing to notions of categorical objects and properties which have officially been renounced. What about the analogue of the second objection I raised to the neoCartesian, that the view makes the world a much fuller place than it actually is? It is immediately obvious that there are many more total collections of space-time points and possible worlds than we would ordinarily regard as constituting physical objects. Suppose we just fasten onto some arbitrary set of space-time points from the actual world, and couple it with arbitrary sets of space-time points from each possible world. Why does the resulting totality not specify a physical object? I think that there are three

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complementary responses that the dispositionalist might immediately make here: (a) that totality has no causal unity; there are no laws governing the effects of intersection with the 'objects' represented by other totalities on the behaviour of the 'object' represented by our totality; (b) there is no apparent unity in the 'object' represented by our totality across possible worlds, no ground for saying that it is one and the same object whose trajectory in different possible worlds is being represented; and (c) there is no reason to say that the totality represents an object which has properties like those of an ordinary physical object: shape, size, weight, and so on. Suppose, though, that we consider the set of space-time points that specifies my trajectory in the actual world. There is a set of space-time points that specifies a trajectory just like mine, only slightly shifted: for example, it might begin five minutes earlier (relative to some reference frame). So this is a trajectory which is, as it were, a temporally delayed shadow of mine. We can repeat the process for every possible world in which I exist. In each world, we take the set of space-time points which is just like the one representing my trajectory in that world, except that the time coordinate has been shifted back by five minutes (relative to some frame of reference). We might say that the totality of such sets specifies my shadow. We can repeat this process for every object with which 1 interact, and for every object which interacts with any object with which I interact, and so on, until we have an enormous collection of shadows. The question now is, why should we not say that shadows are physical objects? This is Shoemaker's Puzzle (Shoemaker 1988). The force of the question becomes apparent when we reflect that there are, after all, regularities holding amongst the behaviour of shadows, regularities which are the shadows of the regularities holding between ordinary physical objects. These regularities hold across possible worlds. Also, any counterfactual which holds of an interaction between two ordinary physical objects—such as that if the first had not been, the second had never existed—will also have a shadow counterfactual which applies to the relevant shadow objects coming up in the rear. It appears that if we have a regularity or counterfactual analysis of causation we cannot explain why ordinary physical objects should be thought to be causally significant but their shadows should not be thought to be causally significant. Shoemaker's own solution is to supplement the regularity and counterfactual analyses of causation. We have to give a special place to the 'genuine' properties. We have to explain causation in terms of lawlike connections holding between the genuine properties of things, or in terms of counterfactual connections between the genuine properties of various objects. Since the 'shadow' objects do not have genuine properties, they do

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not stand in causal relations to one another. Shoemaker considers the question whether we can conclude from this that 'shadow' objects do not exist; that while the set-theoretic entities exist, there are no concrete objects they can be said to represent. Shoemaker would evidently like to be able to draw this conclusion, but confesses himself unable to see any way of making the inference compelling. We can see the problem by asking what a 'genuine' property is. Shoemaker says they are the 'ordinary' properties, the ones we ordinarily recognize. And he fills this out by saying that the paradigms of 'genuine' properties are those to which we have epistemic access; other properties count as genuine because they are related in various ways to the paradigms. Now we can see how this kind of approach might go, even if there are going to be difficult problems about where exactly the boundaries are being drawn, and how it might rule out 'shadow' objects as having causally significant properties. The problem is to see why the notion of causation so defined should have any particular connection with existence. There seems to be something arbitrarily anthropocentric about this way of singling out the 'genuine' properties. Of course we can define an anthropocentric notion if we want to. But why should an anthropocentric notion have anything to do with what exists in the universe? Unless we can find some credible principle at work here, we will have no basis on which shadow objects can be ruled out of existence. At this point, the dispositionalist seems to be in no better a position than the neo-Cartesian who attempts an anthropocentric basis for the distinction between actual extensions which constitute physical objects and actual extensions which do not constitute physical objects. The reason Shoemaker's Puzzle arises is that we are taking it that the issue of which objects exist has to be settled by appeal to purely causal questions, questions about causation which do not presuppose anything about which objects exist. The only way to resolve the puzzle is to drop that assumption: to suppose that our grasp of causation depends on our grasp of existence, so that we can take the existence of certain objects as a datum in addressing questions about causation. So the problem is to understand where this coordinate notion of 'object' comes from. The first thing we can say is that what we need here is the conception of a categorical object, rather than the conception of an object which is merely a collection of dispositions. If we had only the conception of an object as a causal unity, defined by a collection of dispositional interconnections, we would have no answer to Shoemaker's Puzzle. The only way to deal with it is to acknowledge that the idea of a categorical object, as opposed to a causal unity, does play a fundamental role in all singular reference. The important point here is that, unlike Shoemaker's notion of a 'genuine' property, the notion

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of a categorical object or a categorical property is not an anthropocentric notion. Experience reveals the categorical to us, but the categorical is not defined in terms of its relations to experience. I have been arguing that experience of the world is what provides us with our conception of the categorical objects and properties that the world contains. It is only by appealing to this role for experience, properly conceived, that we can meet the 'epistemological' argument for dispositionalism that I rehearsed in section 2. And it is in our understanding of perceptual demonstratives as referring to categorical objects that we put to work this role of experience. Since it is not very evident how else than through the use of experience we could come by the conception of objects and properties as categorical, it seems to be an implication of this approach that we cannot form the conception of unobservable objects and properties as categorical; we can at best conceive of them as dispositions, or complexes of dispositions. The objects and properties with which microphysics deals, for example, are not, in general, observable-—we do not, in any relevant sense, have experience of them. So we will have to conceive of the objects and properties with which microphysics deals as dispositions, or complexes of dispositions. And the correctness of that conclusion has frequently been recognized on independent grounds—on the face of it, we can only conceive of electric charge, for example, as a dispositional characteristic (Popper 1963; cf. Worrall 1996). But as we have just seen, it does not make sense to suppose that all causation might involve only purely dispositional objects and properties, and not involve categorical substances at any point. If that is right, then all our talk of causal relations must ultimately be related to thought about the causal connections among the objects and properties we encounter in experience, conscious attention to which provides our grasp of perceptual demonstratives. The thesis, then, is that all causation must ultimately be related to the patterns of causation among the macroscopic objects we ordinarily encounter. Philosophers sometimes suppose that scientific enquiry could in the end reveal the apparent causal relations among macroscopic objects to be merely epiphenomenal; the real causation being at the microphysical level. But if the approach I am suggesting is correct, there is no such possibility. The causal relations among the macroscopic objects we encounter have to be taken seriously, because all other causal relations can be recognized as causal relations only because of their links to the macroscopic instances of causation. The situation is formally parallel to the response we might make to someone who said that scientific enquiry might ultimately dispense with perceptual demonstratives referring to particular things or places; that there is some other way in which we could identify the things

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and places of interest to science. To this idea Strawson's (1959) response seems perfectly just. This is, in effect, that the possibility of massive reduplication shows that we can never let go of demonstrative identification, without losing our knowledge of which things and places we are referring to. What Shoemaker's Puzzle shows is that if we try to abstract the notion of causation from its links to the objects and properties we ordinarily encounter in experience, we do not achieve a more general or more objective notion of causation; we simply stop talking about causation at all. The point is formally parallel to Strawson's (1959) point about massive reduplication. You might have thought that if we cut the link between all singular reference and perceptual demonstratives, then we will achieve a more general or more objective conception of reference than we would otherwise have. But the possibility of massive reduplication shows that our thought about places and things does not depend on some quite general, purely qualitative method of identification; it is all ultimately anchored in perceptual-demonstrative identification. So if we are identifying particular microscopic objects, or cosmological events far away and long ago, these identifications must always be tied to perceptual-demonstrative identification. If we tried to have identification which did not at all depend on perceptual identification, we would not be talking about particular things or places at all. The analogue of perceptual-demonstrative identification of things and places, for the case of causation, is causation involving the categorical. What I am proposing is that all causation, whether it is causation in the microscopic or causation relating to cosmological events long ago or far away, constitutes causation only because it is ultimately related to causation involving the categorical. If we try to abstract away from the links to causation involving the categorical, then we stop talking about causation at all. The fundamental reason why perceptual demonstratives matter so much in our thinking is, then, that they make available to us the conceptions of particular categorical objects to which all causal thought and talk is anchored. In ordinary thought and speech, we appeal to the idea of the unity of time. When we begin a story with the words, 'Once upon a time', we are saying something about the temporal relation of the events to be described to the present. They have no temporal relation to the present. That is just another way of saying that those events are not real. I am saying that a parallel point hold true for causation. Kant famously maintained the unity of space and time; this is a thesis of the unity of causation. If we say that a set of events stand in no causal relation to the patterns of causation among categorical objects—the parallel, for causation, of the present for time— that is just another way of saying that those events are not real.

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What is the role of experience in explaining our grasp of the ideas of objects and properties as categorical? Suppose that we have someone who is born and raised in an environment in which she never encounters physical objects, though she is adequately nourished and so on and is intelligent enough. Suppose that this person is presented with a description of the causal roles of the objects which actually are all around her, though she cannot as yet perceive them. So she is taught about how objects transmit causal influence over time; that is, she is taught about how what happens to one object can affect that object's later interactions with other things. Similarly, she is taught about how one and the same object can figure in a variety of causal interactions, so that it can be a common cause of correlated phenomena. In effect, she learns a kind of functional characterization of the objects around her, so that she knows there are objects x1, x2, and so on, which have the following characteristics and causal relations ... At this point, she has a full dispositional characterization of these objects: she knows, for each of them, how it tends to behave in interaction with other objects. Now suppose that the situation changes: the walls fall away, she now experiences the objects of which she had only a functional characterization before. What does she gain? You might say that all she gains is some further functional characterization of those objects: she now knows which types of visual sensations they tend to produce. This really would make it mysterious how any of us ever come by the conception of objects as categorical; our heroine is after all now in the same position as you or I. The alternative view, though, is that experience of the object really does provide you with your conception of the object as categorical: it means that you can now appeal to the identity of the object in explaining how it is that causal influence is being transmitted over time and how it is that correlated phenomena are being produced. Before, you knew only that there was something or other which had tendencies to propagate causal influence over time, or to act as a common cause of correlated phenomena. Similarly, if you have someone who has no experience of shapes, but is merely provided with a functional characterization of shape properties— she is told merely that there are properties P1, P2, . . ., which interact with one another in the following ways ..., we can ask what happens when this person does achieve experience of shape properties. You might hold that all you achieve then is knowledge of another functional characteristic of the shape properties: which types of visual sensation they tend to produce. But as before, that makes it hard to see how we can ever come by the conception of shapes as categorical properties. The alternative view is that experience of shapes provides you with the conception of shapes as

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categorical properties, the conception of shapes as causally explaining the object's possession of dispositions, such as a tendency to roll when pushed, that the object has in virtue of having the shape property. These points are what allow us to answer Shoemaker's 'epistemological' argument, which I set out in section 2 above. And as we saw in section 3, we have to find an answer to the 'epistemological' argument, if we are to avoid falling into Shoemaker's Puzzle, and finding ourselves using notions which simply will not sustain the ways in which we ordinarily think about objects and causality. This makes it evident that we cannot think of experience of objects and properties merely as a matter of sensations being produced in the subject. For on that conception of experience, experience itself would at most provide the conception of a tendency to produce the sensations in question. More subtly, the kind of appeal to experience of objects that we are making here is inconsistent with the Representationalist picture of experience that I set out in Chapter 7, section 4. For the Representationalist picture has to face the question: how does the subject understand the representations found in experience, what significance does the subject attach to those representations? And at this point all that the Representationalist has to appeal to are the functional relations in which those representations stand to other representations used by the subject, such as those involved in imagistic reasoning, and ultimately, the functional connections of all those representations to the subject's behaviour. In effect, all that the subject has here to interpret perceptual representations are the connections to imagistic reasoning and behaviour that I described in section 2 above. But as we saw in section 2, those connections to imagistic reasoning and behaviour can at best constitute a grasp of the complexes of dispositions that there are in one's environment. These connections cannot provide the conception of the categorical objects and properties themselves. What we need here is, rather, the kind of Relational View of experience that I set out in Chapters 6 and 7, on which the phenomenal contents of one's experiences of the world are constituted by the character of the scene being viewed. On this account there simply is no representation for the subject to interpret, only the categorical objects and properties themselves constituting the content of the experience. Only the Relational View can explain how it is that we have available a conception of experience on which it explains our grasp of the categorical objects and properties around us, enabling us to answer Shoemaker's 'epistemological' argument and secure our ordinary conception of objects and causality in the face of Shoemaker's Puzzle. Nonetheless, the Relational View still has the problem of explaining the

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connection between our knowledge of the categorical objects and properties around us, and our knowledge of the complexes of dispositions that they ground. What are we to say about this? In section 2,1 said that we can view knowledge of a complex of conditional dispositions possessed by an object as being itself constituted by a complex of dispositions to behaviour on the part of the subject who has that knowledge. Or the knowledge may take the form of possession by the subject of a complex of dispositions to engage in imagistic reasoning. We can remark also that when an object has a particular complex of dispositions in virtue of its possession of a single categorical property, there will be a certain causal unity in that complex of dispositions. And when there is in the environment a particular complex of dispositions—tendencies to mark transmission and so on—in virtue of the existence of a single categorical object, there will again be a certain causal unity to that complex of dispositions. So we can ask how that causal unity is reflected in the subject's knowledge of the complex of dispositions. So far in this section, after all, all that I have said is that the subject has a complex of dispositions to behaviour or to imagistic reasoning, without remarking on any causal unity there might be in that complex of dispositions possessed by the subject. In section 2, though, I suggested that the unity in the subject's complex of dispositions consists in there being a single causal ground for the subject's possession of all those dispositions in the complex. And we are now in a position to see what that single causal ground might be. The single causal ground is the subject's experience of the categorical object or property in question.

5. A Sea of Faces I began this book with the question why conscious attention should matter for an understanding of perceptual demonstratives. We looked at the question whether a blindsighted subject could understand perceptual demonstratives referring to objects in the blind field, and moved to the example in which, as you and I look out over a large dinner table at a sea of faces, you make a remark to me about 'that woman'. I said that it is compelling to common sense that so long as the scene remains a sea of faces to me, and I do not manage to single out visually the person you mean, I do not, in the ordinary way, understand the demonstrative you are using. I can, of course, construct descriptions such as 'the woman you are talking about' and so on, to allow me to interpret your remark, but that is not how we ordinarily understand visual demonstratives. The situation is not, in this regard, significantly altered if I find, to my surprise, that I have the kinds of capacities possessed by the blindsighted patient: that I can correctly answer

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questions about that woman, when forced to guess, or perform simple actions, such as pointing, with regard to that person, when forced to make the attempt. Even though I can answer such questions and perform such actions, so long as the scene remains a sea of faces, I cannot understand your demonstrative in the ordinary way. I understand your demonstrative only when I consciously attend to the right object; only when I highlight that person in experience. So much for common sense; the problem then was to find the theoretical basis of this point, to explain why we find compelling this connection between knowledge of reference and conscious attention to the object. I outlined a Classical View, on which knowledge of reference is what causes and justifies the use that we make of a demonstrative; as we would ordinarily put it, we use a demonstrative the way we do because we know what it stands for. And I argued that it is conscious attention that plays this role: that it is conscious attention to the object that typically causes and justifies our use of particular information-processing procedures in verifying and acting on the basis of propositions about the demonstrated object. In cases such as blindsight, it is possible for the right information-processing procedures to swing onto play for other reasons; but in the ordinary case, what causes and justifies the use of those procedures is the knowledge of reference supplied by conscious attention to the object. The great opponents of a Classical View of knowledge of reference have been Dummett and Quine; but as we saw, their pressure on the question: 'What is it to have knowledge of reference?', simply does not take notice of the possibility of an appeal to conscious attention as providing our knowledge of reference. Conscious attention to the object is a more primitive state than conceptual thought about the thing; sortal concepts are in practice invaluable for directing attention to the object, but the upshot of attention being so directed is a focus on the object that does not itself involve sortal concepts. And with the appeal to conscious attention to the object in place, there is no significant pressure remaining to think that all that there can be to knowledge of reference is a capacity to make use of the term, in verifying and acting on the basis of propositions about the object. Rather, knowledge of reference is explained by conscious attention to the thing. Conscious attention can be directed to an object in different ways; and it can be instructive to find that it is one and the same object to which conscious attention has been directed in different ways. In particular, the way in which conscious attention is directed to an object affects which information-processing procedures will swing into play to verify or act on the basis of demonstrative propositions about the object. Conscious attention to the object has in effect to provide an address for the thing, so that the right information-processing procedures can operate for verification or

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action. And I argued that conscious attention identifies the object by the binding principle for that thing; the principle that the visual system uses to put together all the information relating to that object as all concerning one and the same object. This explains the role of location in demonstrative identification of the object on the basis of vision; in effect, it provides a kind of Fregean sense for the demonstrative. That is not to say, however, that the binding principle provides a descriptive condition which an object must meet in order to be the referent of the demonstrative. An object could be the referent of a demonstrative even though it is not where it seems to be; the role of location is apparent at the conceptual level rather through the phenomenon of immunity to error through misidentification, and in particular, the immunity to error through misidentification of judgement about the location of a demonstrated object. In this chapter, I have been arguing that it is experience of the categorical object that grounds possession of a complex of dispositions to act in one or another way on the object. But, of course, at any one time there may be a large number of different objects in your visual field, and in general you will not be poised to act simultaneously on all of them. What makes the connection between your experience of the object, and your capacity to act with respect to it, your ability to engage in imagistic reasoning in connection with the object, or to verify simple propositions about the thing, is the conscious attention that supplies your knowledge of the reference of the demonstrative.

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