Using Intuitions about Knowledge to Study Reasoning: A Reply to Williams Gilbert H. Harman The Journal of Philosophy, Vol. 75, No. 8. (Aug., 1978), pp. 433-438. Stable URL: http://links.jstor.org/sici?sici=0022-362X%28197808%2975%3A8%3C433%3AUIAKTS%3E2.0.CO%3B2-B The Journal of Philosophy is currently published by Journal of Philosophy, Inc..
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A REPLY TO WILLIAMS
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as the system struggles to restore equilibrium through peripheral re.visions would give way abruptly to widespread changes as the pressure of counterevidence sifts down to the centrally connected, yet more easily overturned, beliefs. I n such a result the causal theory of evidence concurs with Kuhn's account of changes of paradigm (ch. x). The characteristic feature of those Gestalt switches which he takes to be analogous to paradigm shifts (i.e., the duckrabbit and anomalous-card examples) is this threshold effect. MICHAEL P. SMITH JOHN MCLEAN
University of North Carolina at Chapel Hill
USING INTUITIONS ABOUT KNOWLEDGE TO STUDY
REASONING: A REPLY TO WILLIAMS
N a recent article,* Michael Williams vigorously disputes my suggestion (in Thought t and elsewhere) that, given certain assumptions, we can use ordinary judgments about when people know things in order to learn something about when reasoning has occurred and what its principles are. Williams gives three specific instances in which, he alleges, my strategy fails. I will argue that in each instance he overlooks a crucial consideration. The basic assumptions of my approach are (N) that our ordinary judgments about when people know things are, for the most part, right; (0)that reasoning that can give someone knowledge is justified reasoning; and (P) that reasoning that depends essentially on a false proposition cannot give one knowledge. My strategy is to try to devise a theory of inference or reasoning which is compatible with these three assumptions and which accounts for Gettier examples. A Gettier example is a pair of cases in which someone is equally justified in believing something true although he or she knows in the one case and not in the other.1 Pursuit of this strategy "Inference, Justification, and the Analysis of Knowledge," this JOURNAL, 5 (May 1978): 249-263; parenthetical page references to Williams will be to this article. t Princeton, N.J.: University Press, 1973; parenthetical references to my work will be to this book. 1 Edmund Gettier, "Is Justified True Belief Knowledge?" Analysis, XXIII, 6 (June 1963): 121-123. +
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leads me to propose a theory that takes explanatory considerations to be essential to all reasoning.
A purely probabilistic rule of acceptance or inference would allow one to accept any proposition whose probability exceeded a certain specified amount. I argue that we must reject any such rule since it does not allow us to discriminate between essential and inessential propositions in a way that would allow us to use (P) to account for Gettier examples. Suppose Mary has evidence that her friend Nogot owns a Ford. O n the basis of this evidence she concludes that one of her friends owns a Ford. If things are as they seem, she might in this way come to know that one of her friends owns a Ford. But suppose that Nogot does not in fact own a Ford, although Havit, another friend, does.2 If we are to use (P) in order to explain why Mary's reasoning does not in this second case give her knowledge that one of her friends owns a Ford, our theory of reasoning must count as essential to Mary's reasoning the proposition that Nogot owns a Ford. A purely probabilistic rule would not treat this crucial proposition as in any way essential. Given a purely probabilistic rule, Mary could rely entirely on true propositions-her evidence and the fact that her evidence makes it highly probable that one of her friends owns a Ford. So, if a strategy in terms of (N), (O), and (P) is to be followed, purely probabilistic rules of acceptance must be rejected. Now Williams raises what he takes to be an objection here: Given the nature of the evidence, the only way for her to show that the conclusion that one of her friends owns a Ford is sufficiently probable on the evidence is by showing that the conclusion that Nogot owns a Ford is sufficiently probable and then deducing the former from the latter (262).
Actually, it is not clear exactly what reasoning Williams attributes to Mary here. H e may be claiming that Mary must conclude, first, that the probability is high that Nogot owns a Ford; second, that Nogot owns a Ford; third, that one of her friends owns a Ford. T h e essential second conclusion is false, so (P) would prevent such reasoning from giving Mary knowledge. But that is to overlook other ways in which Mary could reason. She could equally well conclude, first, that the probability is high that Nogot owns a Ford; second, that the probability is high that the example is from Keith Lehrer, "Knowledge, Truth, and Evidence," Analysis, xxv, 5 (April 1965): 168-175.
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one of her friends owns a Ford; third, that one of her friends owns a Ford. All these conclusions are true; so (P) would not prevent such reasoning from giving her knowledge. One might wrongly suppose one could evade this by accepting the following principle: "If the proposition that the probability of h is high is essential to certain reasoning, then so is the proposition that h." Given such a principle, the proposition that Nogot owns a Ford would count as essential to the above reasoning, and (P) would prevent such reasoning from giving Mary knowledge. But the principle is clearly unacceptable, since it would prevent Mary from coming to know something she clearly can come to know, namely that the probability is high, given her evidence, that Nogot owns a Ford. Furthermore, no such principles would handle other ways Mary could reason. She could conclude from her evidence, first, that one of her friends has a certificate of title to a Ford, has been driving around in a Ford, and so forth; second, that the probability is high that one of her friends owns a Ford; third, that one of her friends owns a Ford. Again, all these conclusions are true, and this time none of them involves taking a proposition to be highly probable which is in fact false; so there seems no way to use (P) to prevent such reasoning from giving Mary knowledge that one of her friends owns a Ford. Purely probabilistic rules cannot be saved in anything like the way Williams suggests. Turning now to a different issue, I claim that there are reasons to ascribe inference to someone even in cases of so-called direct perceptual knowledge, for example, when one "directly" sees that there is a candle ahead. For there are Gettier examples here tooone sees in a mirror the reflection of a candle that is really off to one side, although there is an unseen candle behind the mirror at the exact place at which the reflected candle appears to be. We can account for such Gettier examples in a way that is uniform with the way we account for other such examples if we suppose that the perceiver's belief is based on inference. Then perceptual Gettier examples can be taken to depend on the truth or falsity of certain propositions that are essential to the perceiver's inference, e.g., the assumption that things look the way they do because there is a candle ahead. Williams disputes this on the following grounds: There are other plausible inferences we might suppose him to have made. For example, he might have thought, "I'm a generally reliable
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observer, i.e., whenever there looks to be a there usually is one; it looks as if there is a reason to suspect any unusual circumstances; front of me." . . . [Tlhis inference involves tially (259).
candle in front of me, candle now; I have no so there is a candle in no false lemmas essen-
But here Williams overlooks the obvious point that we may precisely not suppose that this reasoning by itself is justified if we are pursuing a strategy based on (N), (O), and (P). For that strategy requires us to suppose that any justified reasoning the perceiver can do in this case will involve essentially a proposition that is false when the candle is seen in the mirror. We might suppose, for example, that the perceiver's reasoning requires the conclusion that whatever accounts for there normally being a candle in front of me, when it looks as if there is one, explains why there is a candle in front of me now, when it looks as if there is one.3 That essential proposition is false when the candle is seen in the mirror; so (P) keeps the perceiver's reasoning from giving him knowledge in that case. Turning now to a related issue, suppose the perceiver infers that things look the way they do because there really is a candle there where it looks as if there is. TVilliains points out that this is not all that the perceiver must infer. Suppose that the two candles are on a kind of seesaw so that, if the candle behind the mirror were removed, the second candle would fall over and no longer be visible. Then it is true that things look the way they do to S because there is a candle in front of him. . . . [I]t is not enough that S infer just any explanatory connection between the presence of the candle and the way things appear; he must infer a definite kind of causal involvement. But now trouble threatens from another direction, if we insist on accounting for the case in terms of whatever inference S actually made. Suppose that S has false views about perception. . . . So he infers: things look the way they do because I am bombarding a candle in front of me with visual fire. By principle P, S will not come to know that there is a candle in front of him . . . [even] in a non-Gettier case (260).
But that does not quite follow. What follows is that S does not come to know about the candle (in the case where everything is as it appears, no mirrors, etc.) on the basis of that particular inference. I n this case we will want to ascribe more than one inference 3The importance of this explanatory claim is stressed on page 132 of Thought, to which Williains himself refers in this connection.
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to S. When S comes to know about the candle, he acquires his knowledge from a different and weaker inference (Thought, 133/4). How do we determine what inference to ascribe to S? Our strategy is to ascribe inferences in a way that accounts, given (N), ( 0 ) , and (P), for ordinary judgments about when people know things. Williams's example of the candles on a seesaw shows us that S is not justified i n concluding that things look as they do because there is a candle there, unless S can reach a more specific conclusion as well, although this more specific conclusion may be something as vague as that the presence of the candle there accounts for how things look in the way in which the presence of objects i n the world normally accounts for how things look. Williams expresses considerable doubt about this use of Gettier examples
. . . to determine not just when reasoning has occurred but also what that reasoning has been. I t is very hard to see how this proposal could be backed up, particularly by someone who holds it to be a psychological matter of fact what the real reasons are for a person's believing as he does. I t is difficult to see any connection, logical or empirical, between this matter of fact and the proposed test for it (258).
But, of course, it is part of the strategy I am recommending simply to assume that there is such a connection. That is what assumptions (N), (O), and (P) amount to. So the question is really why we should pursue this strategy. Here the answer can only be: i n order to learn,something about reasoning. I think there are some grounds for thinking that this strategy will turn out to be fruitful. I t is a strategy that helps to account for the appeal of certain principles of statistical reasoning (135-140). It leads to a conception of inference as attempting to promote explanatory coherence in one's over-all view (ch. lo), a conception which has independent plausibility. I t implies that inference is involved in "direct" perception in a way that fits i n well with the findings of psychology (ch. 11). And it offers some insight into the methodological principle of evidential variety.4 Just how fruitful this strategy will turn out to be is, of course, a n empirical question. T h a t does not mean that there are simple empirical tests, independent of this strategy, for attributions of reasoning. Finally, a minor point. Williams indicates in several places that 4 Thought, ch. 9, especially the discussion of principle Q, pp. 151-153. I hope to say more about this in the future.
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he takes me to be trying to provide an "analysis" of "S knows that For the record, I am skeptical about the possibility of any such analysis, and the strategy I advocate does not depend in any way on any analysis of knowledge.0 I am skeptical in part because I am skeptical about all attempts at philosophical analysis and in part because in this particular case it seems to me that the notions of belief, justification, reasons, and inference, the terms in which knowledge is supposedly to be analyzed, are themselves relatively obscure and derivative notions that need to be explained by appeal to the concept of knowledge.
p."
GILBERT H. HARMAN
Princeton University
BOOK REVIEWS Meaning and Modality. CASIMIR LEWY. Cambridge: University Press, 1976. xii, 160 p. $12.95. This book is based on a course of lectures given by Lewy in 1973/74; it represents the author's most recent thinking on topics in philosophical logic and the theory of meaning which have occupied him for over thirty years. The central questions discussed are all of the following type: what is the relation between statements about concepts or propositions and statements about the words or phrases that express those concepts or propositions? Lewy takes as his point of departure some remarks of John Wisdom. I n "Metaphysics and Verification" l Wisdom writes: T o say that analytic statements are verbal is useful if one wishes to get rid of the idea that they differ from statements about words i n the way that statements about dogs differ from statements about cats . . . for every statement about abstract entities-propositions, characteristics-there is a verbal statement which makes the same factual claims though its meaning is different (62).
T o illustrate his point Wisdom gives the following example: Suppose a Chinaman is decoding an English message, and does not know the meaning either of 'vixen' or of 'female fox', but says after Contrary to what Williams says on p. 252. XLVII, 188 (October 1938): 452-498; reprinbed in Philosophy a n d Psycho-analysis (New York: Philosophical Library, 1953), pp. 51-101; quotes are from the book. 6
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