Sense-Perception and Matter

fnternationalLibrary of Psychology Philosophy and Scientific Method GENERAL

EDITOR-C.

K.

OGDEN,

M.lt.

(Magdalcw

Colkgc,

Cambtidgcl

ANALysrs or Prncrprrox J. R. Suyrsrss Tueonv ARIsrorLE's or CoNTRARTETv J. P. ANToN Bewrrru's THEoRy oF Frcrroxs C, K. Oopex BERTRAND Russerr's CoNSrRUcrroN op Exrenxer Wonrp C. A. Fnlrz Cslnecren AND THE UNcoNscrous I. H, VAN DER Hoop THE CHrLD's Corceprrox oF GEoMETRY . Irrv Prrorr jerx Txe Cnrro's CoNcEprroN oF NuMBER Prrorr TsB Cxrro's CoNcEpfloN or Seece Precer Jeel jeet THE CHrLD's Cotceprrol or rse Wonlo Prrcer Cnrue exo Cvsrou rr SAVAGE SocrETy B.-Merrrowsxr ErHtcs AND THE HrsroRy oF PHrlosopgy C. D. Bnoep Frve Types or Erurc& Tapony C D. BRo^D Tne Fourpmroxs or Gpouerny . Nrcoo Jrrt Tue F-ouroerroxs or Mlrneurrrcs F.-P. RAMsEy Grsrert TseonY Bnuxo PerBnuetx THE GRowrH or rnr Mrlo . K. KoFFKA A HrsroRrc^L INTRoDUcrroN To MoDERN PsycHolooy G, Munpsy Tue Hrsrony or Mfnnrllrsx F A. LaNGE Iorolocy AND UToplA Krrr Mrxlneru THE PRAcrrcE lro TxeotY oF INDTVTDUAL PsycHolocy A. ADLER AND REAsoNrNc rN THE CHILD Juocuelr JEAN PTaGET Trr Lrrcuece AND THoucHT or tue Cnrrp Prrcer Jrrx Tar Lrurrs or ScrrxcE . Lrol Cus.lsrrx Loorc rr Sruprrs GEoRGE Hnxnrx vox Wnrcnr Locrcel Sywrlx or LANcuacE R. Crntrr Txu MrerrNc oF MEANTNG C. K. OGDEN AND I. A. Rrcuenps Mryrer DevrropMENT oF rxe Cutrp KaRL BUHLER Txe MrNrrrrrv or Apes W K6HLER METApHysrcAL F-ouNDATroNs or Moprnx Scrrtcp E. A. Bunrr METHoDS rlp Cnrrpnrl oF REASoNING R. Cnrwssey-Wrrrrrus THE MIND AND rrs PLAcE lx Nrtunn C. D Bnoro MoRAL JUDGMENT or rqe Cnrlo Prrcrr Jrer THE NATuRE oF LaucHTER J. C. Gnecorv THE N^TURE oF MATHEuATtcs Mrx Brecx Onrcrp or INTELLTGENCE rr rxE Cxrln letx Precsr - E. ZELLEN C)urLrNEs oF THE HrsroRl' or Gnerx PErlosopHy PHrLosoPBtcaL STUDIES G. E. MooRE PHrlosopHy or "As IF" H. Versrlcrn Psrrosopny or Psrnce T. BiicKLER PHILosoPHY oF PLATo R-. C. Loocc Pxllosopgy oF THE Ur.coNScIoUs E. voI HARTMANN PLATo AND PARMENTDES F. M. CoRNFoRD PLATo's CosMoLocY F, M, Conrrono PLATo's PHAEDo R. S BLucK Prero's Tneonv or Anr R. C. LoDGE Prrro' s Turony oF KNowLEDcE . F. M. Corlroao Tue Pnrrcreres or Grsrllr PsYcHolocy K KortsKA THE PRrNcrpLEs oF LTTERARy Cxrrrcrsu I. A RTCHARDs PsvcHE E. Rsooe PstcHolocrcAl TYPES C. G. Jr:so Tne Ps[cxorooy oF An*rMALs F. Arveioes Tse Psycaorocy or Culnlcrrn A. A Roarcr THE Psycgolocy or CqrLontx's DRAwTNGs HELGA ENG THE PsYcHolocy or Cors crousrrss C. Dery ltrvc THE PsYcHolocy oF INTELLTGENCE Prrcrt Jru Rrrsoxs AND FArrHs Nlxrrl Svrnr RELrcroN PHTLosopHY AND PslcHrcAL RESEARCH C, D. BRoAD ScrexrrrrcTHoucHT C D Broro SENsE-PERcEprroN AND MATTER M E. Lerx Srx rro REpREssroN rl Srvror SocIEry B Mrrr xowsxr Specullrroxs T. E HuLME SPrRr r oF LANcuAcE K. VossLER Tue SrnucrunB or Mgrfnysrcs . M. LAzERowrrz . THronetrcel BroLoGy J. voN UExKijLL Tsouc ur AND TEE BRAIN Hexnr Prenox 'l'RAcrATUs Locrco-Pnrlosorurcus . Lupwrc WrtrcBnsrerx

The Mind and its Placein Nature

By

C. D. BROAD, M.A., Lnr.D. Fellow and Lecturer in the Moral Sciences, Trhdty College, Cambrid'ge Author of Perception, Physics, and Reality, and. Scienti/tc Thought

SE V E N TH

R OU TLE D GE

I MP N E S S I O N

& KEG AN

PAUL

Broadway House, 68-74 Carter Lane London, E.C4.

I - TD

SECTION B Introductory Remarks " If there's a screw loose in a heavenly body, that's philosophy; and if there's a screw loose in a earthly body, that's philosophy too; or it may be that there's sometimes a little metaphysics in it, but that's not often. Philosophy's the chap for me. If a parent asks a question in the classical, commercial, or mathematical line, says I gravely, 'Why, sir, in the first pliace, are you a pbilosopher ?' 'No, Mr Squeers,' he says, 'I ain't.' 'Then, sir,' says I, 'I am sorry for you, for I shan't be able to explain it.' Naturally tbe parent goes away and wishes he was a philosopher, and, equally naturally, thinks I'm one." (Drcxrrs, Nioholas Nichleby)

SECTION B THn MlNo's KNowLeDGE oF Exrsrrxrs Introductory Remarks IN this Section I am going to consider the knowledge w hi ch a human mi nd has of m at t er , of it self , and of other minds. Knowledge is a transaction with two sides to it, the mind rvhich knows and the objects knorvn. A critical discussion of the mind's alleged knowledge of anything should therefore help to clear our i deas both of the n at ur e of t he m ind and it sact ivit ies and of the nature of the objects which it knows. Thus, i n di scussi ng the mi n d's knor vledge of m at t er t hr ough perception, we ought to learn something both of the nature of the mi nd as a per cipient and of t he nat ur e and reality of matter. And, when rve consider the mi nd' s know l edge of i t self and of ot her m inds, we ought to learn something of the nature of the mind from two sides. Common-sense believes itself to know pretty rvel l w hat mi nd i s and what m at t er is. t hough it m ight have great dilficulties in putting its beliefs into clear and consistent language. So far rve have accepted these claims without question, and have discussed We have certain problems subject to this condition. now to pass from the level of enlightened commonBy this I mean sense to that of Critical Philosophy. that rve have to consider carefully the sources of our alleged knorvledge of matter and of mind, and to see horv far we can still accept the common-sense view of these trvo enti ti es i n th e light of t his addit ional inf or m ati on. E ven i f the comm on- seuse view should not need

r38 MIND'S KNOWLEDGE OF EXISTENTS coryection,it will certainly need careful and explicit state?nent ; and, when stated, it rnay seem unfamiliar and even shocking to common-sense. It would, I think, be admitted by every one that such knowledge as rre have of matter is based on senseperceptionand memory. Each nran'ssense-perception and memory are supplementedby communication with other minds which claim to tell him what they have perceivedand remembered. Thus the problem of our knorvledgeof matter inevitably involves the problem of our kuowledgeof other minds. There is lessagreement about the sources of our knowledge of other minds. But I suppose that every one would admit that a necessary, if not a sufficient, condition of such knowledge is that we should listen to the sounds and note the gestures of other human bodies. So the problem of our knowledge of other minds is in turn bound up with the problem of our knowledge of matter. The exact connexion between these two problems will have to be consideredin some detail. There is, again, a lack of agreement about the sources of a mind's knowledge of itself. I suppose that every one would admit that memory is involved here as much as in our knowledge of matter. But, on the one hand, some people deny the existenceof a mental activity, called " introspection," by which a mind observesitself or the events belonging to it. And ttrose who admit the existenceof this activity differ a good deal about its limitations I for some think that we can introspect both acts and states, whilst others seem to hold that we can introspectstatesbut not acts. On the other hand, some people who admit the existence of introspection and give it extensive powers would hold that it is not the only or the main source of our knowledge of our own minds. In anycase lve can seeat oncethat the three problems are most intimately linked, and that no treatment of one can be satisfactorvwithout a treatment of the rest.

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I have already tried to show this linkage between the problem of our knowledge of matter and the problern of our knowledge of other minds. There seems to be an equally close connexion between the problem of our knowledge of our own minds and that of our knorvledge of other minds. For, even if it be not the whole truth, it certainly seems an important part of the truth to say that our beliefsabout other minds are basedon analogies with what rve knorv of our own. The other point which is alreadyclear is that memory is involved in all three kinds of knowledge. Hence the divisions of this Section will be the following : First I shall treat Sense-perception, then Memory, then Our Knowledgeof our outn Minds, and then Our Knozuledgeof ot/rer Minds. The reader will remember that this division is necessary,becausewe cannot say everything at once, but that none of these four chapters is likely to be satisfactorywhen taken by itself.

SENSE-PERCEPTION

CHAPTER IV Sense-perception and Matter IN this chapter I propose to give a sketch of the problem o f th e nr ind' s k nor v l e d g e o f ma tte r th ro u g h the senses. I sh a ll nec es s ar ily b e c o v e ri n g a g a i n g ro u n d w hi ch I have already been over in my Scienttf,c Thoughl, and I must refer the reader to the Second Part of that book fo r a det ailed s t at em e n t a n d d e fe n c e o f m y v i e w s on the su b j e c t . Her e I s h a l l b e a s b ri e f a s p o s s i b l e, and i n co n se quenc es om er v h a t d o g ma ti c . I s h a l l , h o rvever, be a p p roac hing t he pr o b l e m fro u r a s l i g h tl y d i ffe r ent angl e, so th a t I hope t hat th i s c h a p te r w i l l n o t b e mere vai n re p e ti t ion. Let us begin rvith something Perceptual Eituations. that every one, whatever his philosophical views may be, would admit to be a fact. Some people rvould raise d o u b t s about t he e x i s te n c e o f p h y s i c a l o b j e c ts, such as ch a i rs , t ables , bel l s , e tc . So me p e o p l e rvoul d rai se d o u b t s abor r t t he e x i s te n c e o f s e l v e s o r mi n ds rvhi ch p e rceiv e s uc h obje c ts . Bu t n o o n e d o u b ts that such p h ra s es as " I s ee a b e l l " , ttl fe e l a b e l l " , " I hear a bell ", indicate states of affairs rvhich actually exist from ti me t o t im e. P eo p l e d o n o t b e g i n to q u a rrel ti l l they try to ana[trl such situations, and to ask rvhat must be me a n t by t t I " , by th e t' b e l l " , a n d b y " h e a ri ng" , i f i t i s to b e t r ue t hat " I h e a r a b e l l " . W h e n th ey do thi s th e y ar e liable t o fi n d th a t th e o n l y ' s e n s e s of " l " , " b e l l " , and " hea r" , rv h i c h rv i l l rn a k e th e statement true are very dilferent from those rvhich rve are wont to a tta ch t o t hos e wo rd s . l f th i s s h o u l d h a p p e n, i t sti l l

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remains true, of course, that the phrases " I hear a bel l " and t' I see a chair " st and f or r eal st at es of affairs rvhich differ in certain specific rvays from each other ; but these states of affairs may be extremely di fferent i n thei r struct ur e and t heir com ponent s f r om rvhat the form of words which is used to indicate them would naturally suggest to us. I rvi l l cal l such si tuat ions as ar e nat ur ally indicat ed by phrases l i ke t' I am seeinga chair " or t t I am hear ing a bell " by the name of " Perceptual Situations ". I take it then that every one agrees that there are such tlrings as Perceptual Situations. Can we all agree to go any further together before parting company ? I think rve obviously can. (i) There are certain situati ons, w hi ch undoubted ly ar ise f r om t im e t o t im e, r vhich are indicated by such phrases as " I feel tired " or " I feel cross ". I think that every one rvotrld admit that percepttra! situations differ radically from these. Suppose we compare the situations indicated by the tw o phrases tt I feel cro ss " and t t I hear a bell ". When rve feel cross we are not feeling sonething but are feeling setmehozu. When we hear a bell we no doubt are feeling somehoza,but the important point about the perceptual situation is that we claim to be in cognitive contact rvith something other than ourselves and our states. This cl ai m i s j ust as obvi ous in t hose per cept ual sit uat ions w hi ch are commonl y b elieved t o be delusive as in t hose w hi ch are commonl y be lieved t o be ver idical. The t wo si tuati ons ttI am hearing a bell" and t 'I am seeing pink rats " agree completely in this respect' and both differ in this respect from the situation " I feel cross ". I w i l l express the di ffe r ence bet Neen t he t r vo kinds of si tuati on by sayi ng th at t he one does and t he ot her does not have an " epistemological object ". The bellsituation and the pink-rat-situation both have epistemological objects ; the situation indicated by " I feel cross " has no epi stemol ogi cal object . I VI y m ot ive in adding the qualifying rvord " epistemological " is that other-

r42 MIND',S KNOWLEDGE OF EXISTENTS wi se s om e br ight s p i ri t w i l l a t o n c e c o mp l a i n that the pink-rat situation has no object. What he really means is of course that there is no ontological object, corresponding to the epistemologicalobject which the situation certainly has 1 i.e,, that the situation involves a certain claim which the physical world refuses to meet. I had better take this opportunity to anticipate another purely verbal objection which someone is sure to make. Someone is certain to say : " We don't really sae pink rats, for there are none; we only think that we see them." To this I answer by admitting that words like " seeing ", et c . , d o , m o s t u n fo rtu n a te l y , i n troduce the "h e a r ing" , fallacy many questions " like the barrister's query : of " you leave off beating your wife ? " The When did " phrase '( I see so-and-so" zs taken in ordinary life to mean : " There is a perceptual situation of the visual kind of which I anr subject, This has such and such an epistemological object. And there is a physical object corresponding to this epistemological object ". If a second person has reason to believe that the third of these propositions is false, he will be inclined to say: ('You ar e not r e a l l y s e e i n g s o -a n d -s o ; y o u onl y thi nk that you are seeing it ". Norv words like " seeing " and ('h e a r ing" ar e ho p e l e s s fo r o u r p re s e n t p u rpose i f they are to be interpreted in this way. I therefore wish it to be clearly understood that I shall depart so far from common usage as to say that a man sees a pink rat, provided he is subject of a perceptual situation which has a pink rat as an epistemological object and is of the visual kind, regardless of whether there is a physical pink rat corresponding to this epistemological object. With these verbal explanations I think that every one would admit that there are perceptuat situations and that all perceptual situations necessarily have epistemological objects. Common language, though far from consistent, expresses the difference between th e t wo k inds of s i tu a ti o n i n th e fo l l o w i n g rvay: It tends to express a situation which has no epistemo-

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logical object by the verb " to feel " followed by an adj ecti ve or adverb, such as "cr oss" or t t cr ossly". It tends to express a situation which has an epistemological object by some special transitive verb, such as t' see" or ttheart' , an d by a subst ant ive- nam e which, in an inflected language, would be put in the accusative case. In order to know what is the epistemological object of any situation it is only necessary to know the meaning of this substantive-word in the phrase which In order to know whether expresses the situation. the situation has an ontolog'ical as rvell as an episteuoIog'icalobject it is plainly not enough to consider the meanings of utords; the question can be settled only, if at all, by a careful enquiry into the nature and connexions of tltings. (ii) It would further be admitted by every one that not all situations which have an epistemological object are perceptual. (a) In the first place there are situations whose epistemological objects are such that no pltysical object could correspond to them, though ontological objects of a different kind might corr:espond to them. 8,g., the situation expressed by the phrase " I notice that I am acting spitefully" has an epistemological object. But, if there be an ontological object which corresponds to this epistemological object, it certainly cannot be any purely physical thing or event. It must be some process rvhi ch i s goi ng on in m y nr ind. I will say that the epistemological object of a situation which has such an object may be " of the physical kind ", or " of the psychical kind ", or possibly of many other kinds. It would be agreed, I think, that the epistemological object of any perceptual situation must be of the physical kind ; and this simply means that, if there be an ontological object corresponding to it, it must be a physical object or event. (/) It rvould further be admitted that a situation may have an epistemological object of the physical kind and yet not be a perceptual situation. Compare the trvo

r44 MIND',SKNOWLEDGE OF EXISTENTS ph ra se s " I am hear in g a b e l l " a n d .,I a m th i n ki ng of a bell". The epistemological objects of the two situations which are expressed by these trvo phrases are both of th e p h y s ic al k ind; th e y m i g h t, s o fa ra s o n e c an see, even be identical. But every one recognises that there is a deep difference betweelt the situations. We should vaguely express one part ofthis difference by saying that in the perceptual situation we are ,, in more immediate t ouch wi th " t he bell th a n i n th e th o u g h t-s i tu ati on. This difference is indicated in speech by the fact that the phrase which expresses the thought-situation contains a pr e p o si ti on lik e t ( of " o r ,, a b o u t " b e fo re th e s u b s tanti vervord rvhich expresses the epistemological object of the s itu a ti o n , whils t t her e i s i n g e n e ra l n o s u c h w o rd i n the phrase rvhich stands for the perceptual situation. I will express this difference by saying that a perceptual situ a ti o n is " int uit iv e " , w h i l s t a th o u g h t-s i tu a ti o n w i th t he sa me k ind of epis t e m o l o g i c a l o b j e c t i s ,,d i s c u rsi ve " . Here again I suppose that every one would admit the distinction which I am drawing, though different philosophers would differ violently about the proper analysis of it. I do not wish to deny that there may be som e th i n g int uit iv e in e v e ry th o u g h t - s i tu a ti o n and s ome th i n g dis c ur s iv e in e v e ry p e rc e p tu a l s i tu a ti o n . B ut I t h i n k th at it is plainl y tru e rh a t rv h a t s tri k e s u s about t he si tu a tion c alled , , h e a ri n g a b e l l " i s i ts i n tui ti ve character, and that what strikes us about the situation call e d .. t hink ing abo u t a b e l l " i s i ts d i s cursi ve character. (r) We m us t nex t n o ti c e th a t th e re a re s i tuati ons which have an epistemological object of the physical kind , a n d ar e int uit iv e a n c l n o t d i s c u rs i v e , a n d y e t w oul d not b e called per c ept ua l . T h e mo s t o b v i o u s e x a mpl es ar e me mor y - s it uat ions . I m a y h a v e a g e n tri n e memory of the tie which my friend was wearing yesterday. T his si tuat ion has an e p i s te m o l o g i c a l o b j e c t of the physi ca l kind. A nd it i s i n tu i ti v e , i n th e s e n s e i n rvhi ch s eei n g h i s t ie r v ould be i n tu i ti v e a n d m e re l y th i n k ing of

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his tie would not be. But it is quite different from a perceptrral situation. And one important difference, at any rate, is this. It is of the essence of a perceptual situation that it claims to reveal an object as it ,.t at the ti me w hen the si tuati on i s going on ; and it is of t he essence of a memory-situation that it claims to reveal an object as it zaa.ssome time before the memory-situation began. It is perfectly true that, when I see a distant star, this is an instance of a perceptual situation ; and it is true that there is strong reason to believe that, if the situation reveals a physical object at all, it reveals it as it zuaslong before tbe situation began. But this does not affect the truth of my statement. For it is'certainly true that, so long as we remain at the level of perception and do not introduce inferences, the situation doesclairn to reveal the star as it now is ; and, if it did not, it would not be a perceptual situation. (iii) There is one other point which I suppose that every one would admit to be common and peculiar to perceptual situations. This is the fact that sensation pl ays an uni que and i ndi spe nsable par t in t hem . I do But it not thi nk i t i s possi bl e to d ef ine "sensat ion". will one every which is possible to give illustrations red a of alvare I am recognise. Such statements as " t'I ont and so flash ", am aware of a squeaky noise ", are certainly sometimes true ; and they express a kind of situation which is perfectly familiar to every one. Whenever such a statement is true, there exists a sensation. And it would be admitted that there cannot be perceptual situations without sensations. I think that it would also be admitted that sensations play a part in perceptual situations which they do not play in any other kind of situation. I will express this fact by tt saying that perceptual situations are sensuous ". rvhich every one on We may now sum up the points is really agreed, however much they may differ in their language, as follows: There certainly are perceptual situations ; they are intuitive and sensuous and they

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have epistemological objects of the physical kind, which are given as simultaneous with the situation itself. This is of course neither a definition of the per c ept ual s it u a ti o n n o r a n a n a l y s i s o f i t; i t i s si mpl y a set of propositions which are admittedly all true of perceptual situations and not all true of anything else. Does the agreement stretch any further than this ? I think that it can be carried one step further. I think that every one is really agreed about the irreducible minimum of characteristics that a thing would have to possess in order to count as a physical object. Now it is agreed that all perceptual situations claim to reveal objects of this kind, tbr that is what we mean when we say that they all have epistemological objects of the physical kind. Let us then raise the question : What do zae understand by a " Physical Object" ? The following marks seern to characterise anything that we should be willing to call a " physical object ". (i) It is conceived to be a strand of history of reasonably long duration, as compared with that of our specious present, and possessed of a certain characteristic unity and continuity throughout the period during which it is said to last. A mere flash would hardly be counted as a physical object; a penny, if it has the characteristics which it is commonly believed to have, would count as one. (ii) It is conceived to be quite literally extended in space. It has some size and some shape, an inside as well as an outside, and it stands in spatial relations to other physical objects. Strictly speaking, we ought rather to say that each momentary cross-section of the history of the object has these characteristics, and that the nearer together two such cross-sections are in time the more nearly alike they will be in their spatial properties. It may happen, as a particular case, that all the momentary cross-sections of a certain physical object within a certain stretch of time are exactly alike in all their spatial characteristics. In this case we should say that, for this stretch of time, the object had

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(iii) It is conkept its shape and position unchanged. objects physical ceirred to persist and interact with other perceived " is rewhen no one perceives it. " Being garded as something which happens from time to time io physical objects, but which is not essential to their and makes no further difference to their "*istence, qualities either at the time or afterwards. (iv) It is conceived to be perceptible by a number of different observers at the same time, as well as by one observer (v) It is supposed to combine a at various times. number of other qualities beside the spatio-temporal characteristics already mentioned. Some of these qualities reveal themselves in one way, others in another way ; thus colour reveals itself to sight, hardness and temperature to touch, and so on. In order that a certain kind of quality may reveal itself to a certain mind it seems necessarythat the body which this mind animates shall be gifted rvith appropriate sense-organs' Thus it is held tb be quite possible that physical objects may have many qualities which are never revealed to us' simply ne.anie we lack the necessary sense-organs' If there-be no things which have all these characteristics, there are, strictly speaking, no physical objects ; and all perceptual situations are delusive. But of course there might still be things which literally possessed some of these characteristics and to which the rest could be ascribed in various more or less Pickwickian senses' In that case it would be a matter of taste whether we sti l l sai d that w e believed in physical object s; but it would be a matter of fact that all perceptual situations are delusive in certain respects. E.g., if the ordinary scientific view, as commonly interpretedr were right' all perceptual situations would be delusive in so far as they to reveal objects which literally have colour' taste' il"ismell, etc. But they would be veridical in so far as they claim to reveal objects which literally have shape, If Berkeley be right' all sizi, position, and motion. perceptual situations are delusive in every respect except

r48 MIND'S KNOWLEDGE OF EXISTENTS in their claim to reveal sonretlting independent of and common to percipients. This " something " will be the permanent habits of volition according to which God sends us such and such sensations on such and such occasions. The typical linAnelysis of Perceptual Situations. guistic expression for a perceptual situation is a sentence l i k e " I s ee th e c h a i r" o r " I h e a r th e bel l " . Thi s mode of expression inevitably suggests a certain mode of analysis for the perceptual situation. It suggests that it consists of me and the physical object whose name appears in the phrase, related directly by an asymmetrical two-term relation rvhich is indicated by the verb. And this suggests that the adrnitted existence of the situation guarantees the existence of me and of the physical object. Horv far can this simple-minded view b e m aint ained ? In philosophy it is equally silly to be a slave to common speech or to neglect it. When we remember that it represents the analyses made unconsciously for practical ends by our prehistoric ancestors we shall not be inclined to treat it as an oracle. When we remember that they were probably no greater fools than we are, we shall recognise that it is likely to accord at any rate rvith the more obvious facts, and that it will be wise to take it as our starting-point and to work from it. It is plausible to suppose that the perceptual situation which language describes by the phrase " I see a chair" does contain two outstanding constituents related by an asymmetrical trvo-term relation. But it is quite another question whether these two constituents can possibly be what is commonly understood by 't me " and by t' c hair " . Let u s n o w c o n s i d e r th i s q u esti on, fi rst as regards the object and then as regards the subject. The ObjectiaeConstituent. Even if we had never had any reason to believe that some perceptual situations a r e delus iv e, th i s e x tre me l y s i mp l e -m inded anal ysi s

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rvould need to be modified considerably. (a) It would be admitted that in any one perceptual situation I am never aware of the zahole of the surface of a physical object, in the sense in which I do seem to be aware of a part of it. Nobody who was looking at a bell would seriously maintain that, at a given moment' he is aware of the far side and the inside of the bell, in the same sense in which he would claim to be aware of a certain part of the outside which is facing him at the time. And by a " bell " we certainly mean something which has a closed surface with an inside as rvell as an outside, and not merely a patch with indefinite boundaries. Thus the most we could say. is : " The perceptual situation contains as a constituent something which is (/) A similar in fact part of the.surface of a bell". put on the naive be must time to regard with limitation By a situation. perceptual analysis of the " bell" rve something duration; mean something of considerable stretch does, certainly which certainly may, and almost situation perceptual out in time beyond the limits of the in which I am aware of it. Now no one rvould maintain that the parts of the history of the bell which come before the beginning and after the end of a certain perceptuat situation are " given " to him in that perceptual situation in the same sense in rvhich the contemporary slice of the bell's history is " given ". Thus we have no right to say that the situation, described by the phrase " I am seeing the bell " contains the bell as a constituent ; at most we can say that it contains as a constituent a short event which is in fact a slice of a longer strand of history, and that this longer strand is the history of a certain bell. (c) It would be admitted by every one that a bell is something more than a coloured surface, more than a cold hard surface, and so on. Now, so long as I merely look at a bell, its colour only is revealed to me; its temperature or hardness are certainly not reveated in the same sense at that time. S i nri l arl y, w hen I m er ely t ouch t he bell, only it s

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temperature and hardness are revealed to me; its colour is certainly not revealed to me in the same sense at that ti me . O nc e again th e n I h a v e n o ri g h t to say that the bell is a constituent of either of these perceptual situati o n s. A t m os t I m a y s a y th e re i s a c o n s ti t uent rvhi cl r d i sp l ay s c er t ain q u a l i ti e s , a n d th a t th i s same constituent has in fact other qualities rvhich would be d i sp l ay ed under o th e r c o n d i ti o n s . Thus rve are forced to modify the first naive analysis o f " I s ee a bell " a t l e a s t i n th e fo l l o w i n g respects: We c annot hold t h a t th i s s i tu a ti o n l i te ra l l y c ontai ns the bell itself as a constituent. The most we can say is that the situation contains me and somet/aingrelated by an asymmetrical trvo-term relation ; that this something is in fact a part of a larger surface, and is al.so a short slice of a longer strand of history ; that it has in fact o th e r qualit ies be s i d e th o s e w h i c h a re s e n suousl y reve a l e d t o m e in t h i s s i tu a ti o n ; a n d th a t th i s spati al l y l a rg er and t em pora l l y l o n g e r w h o l e , w i th the qual i ti es wh i ch ar e not r ev e a l e d s e n s u o u s l y i n th i s s i tuati on, i s a ce rta in bell. T his w h o l e i s th e e p i s te m o l o gi cal obj ect o f th e s it uat ion ex p re s s e d b y th e p h ra s e ' ( I am seei ng th e bell " . A nd, e v e n i f i t b e g ra n te d th a t there i s an ontological object which corresponds accurately to the e p i stem ologic al ob j e c t, w e c a n n o t a d mi t th a t zt i s bodi l y a co n s t it uent of t h e s i tu a ti o n . T h e m o s t that w e can g ra n t is t hat a s m a l l s p a ti o -te mp o ra l fra g ment of the o n to l ogic al objec t i s l i te ra l l y a c o n s ti tu e n t o f the si tuati o n , and t hat a s m a l l s e l e c ti o n o f th e q u a l i ti es of thi s fra g ment is s ens uo u s l y re v e a l e d i n th e s i tu a ti o n. No.n' oi course the existence of any complex whole e n ta ils t he ex is t en c e o f a n y th i n g th a t re a l l y i s a consti tu e nt of it . T he re i s n o d o u b t th a t s u c h si tuati ons as are described by the phrase " I see a bell " exist. An d t her e is no d o u b t th a t th e e p i s te rh o l o g i cal obj ect o f su c h a s it uat ion i s s o m e th i n g h a v i n g a l l th e characteri sti cs r v hic h ar e, c o n n o te d b y th e w o rd " b e l l " . If then th e p er c ept ual s itu a ti o n d i d c o n ta i n a s a consti tuent

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something rvhich accurately corresponds to its epistemological object, the existence of the former would guarantee that of the latter. But it is norv clear that the si tuati on does not and could not cont ain as a consti tuent anythi ng that could pr oper ly be denot ed by the word " bell ". Hence the existence of the situation denoted by the phrase , , I see t he bell " does not suf f ice to guarantee the existence of a certain thing denoted by the phrase ' (the b ell ". I t is plain t hen t hat t her e is involved in every perceptual situation another factor beside me and a certain spatio-temporally extended particular. This is the conviction that this particular something is not isolated and self-subsistent, and is not compl etel y reveal ed in all it s qualit ies; but t hat it is spatio-temporally a part of a larger whole of a certain characteristic kind, viz., a certain physical object, and that this whole has other qualities beside those which are sensuously manifested in the perceptual situation. Let us cal l the const it uent about which r ve believe these propositions 'r the objective constituent of the perceptual situation ". And let us call this conviction rvhich we have about the objective constituent .. the external reference of the situation ". I give it this name because it clearly points spatially, temporally; and qualitatively, beyond the situation and what is contai ned i n and sen suously m anif est ed in it . I will now say something more about the external reference of a perceptual situation. The Erternal Re.lference. (a) lt would be false psychologically to say that we infer from the nature of the objective constituent and from any other knowledge that we may have that it is part of a larger spatio-temporal rvhole of a certain specific kind. It is perfectly evident that rve do nothing of the sort. Of course we can talk of " unconscious inferences ", if we like ; but at most thi s means that w e i n f act r each wit hout inf er ence t he l < i nd of concl usi on w hi ch could be def ended by inf er ence i f i t w ere chal l enged, ( b) lt would be f alse logically

r52 MIND'S KNOWLEDGE OF EXISTENTS to say that the beliefs rvhich are an essential factor in a perceptual situation, though not reached by inference, could be justified by inference. I can see no way of validly inferring from the mere presence of an objective constituent, which sensuously manifests such and such qualities, that this constituent is part of a larger spatio. temporal whole which is not a constituent of the situation a n d has ot her q u a l i ti e s . It mi g h t p e rh a ps be argued th at , alt hough th i s c a n n o t b e i n fe rre d rvi th certai nty from any one or fro m a n y n u mb e r o f p e rc e ptual si tuati ons taken separately, it might be inferred rvith probability fr om a num ber o f s u c h s i tu a ti o n s ta k e n together and co ns ider ed in t h e i r mu tu a l re l a ti o n s . I s hal l go further i n t o t his ques ti o n a l i ttl e l a te r i n th e c h apter. B ut i t is evident that, even if the general validity of such i nf er enc es be ad m i tte d , th e i r c o n c l u s i o n woul d be something m uc h les s d e fi n i te th a n th e b e l i e f th at the obj ecti ve constituent of a perceptual situation is a spatio-temporal part of a larger whole which corresponds accurately to the epistemological object of the situarion. Strictly speaking, the most that could be directly inferred from a study of perceptual situations and their mutual relations is that probably such and such a perceptual situation rvill be accompanied by such and such others, belonging to different observers; or that it will probably be succeeded by such and such other perceptual situations, provided I make such and such movements. The notion of persistent physical objects is logically merely a hypotbesis to explain such correlations between perceptual si tuat ions ; and th e c o mmo n -s e n s eb e l i e fth a t the obj ecti ve constituents of perceptual situations are literally spatiotemporal parts of persistent physical objects is logically one veryspecial form of this hypothesis. It is tolerably obvious that the actual strength of our conviction that in perception we are in direct cognitive contact with literal spatio-temporal parts of a physical object, which corresponds to the epistemological object of the situa_ tion, could not be justified by inference. (r) Lastly, rve

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express the position far too intellectually, when we say that in a perceptual situation we are acquainted with an obj ecti ve consti tuent which sensuously m anif est s cer t ain qual i ti es, and tha t t his acquaint ance gives r ise t o and is accompanied by a belief that the constituent is part of a larger spatio-temporal whole of a specific kind. We must remember that ignorant men, and presumably animals, perceive as well as philosophers ; and we must beware of mixing up our analysis of the perceptual situation with the situation as it actually exists. It would be nearer the truth to say that, at the purely perceptual level, people do not have the special experience cal l ed " bel i ef " or "judgm ent ". To believe so and so at this level really means to act as it would be reasonable to act zf one believed so and so, and to be surprised if the action turns out to be a failure. We automatically adjust our sense-organs in a certairr rvay ; w e make i nci pi ent m ovem ent s I and so on. These ar e of course accompanied by characteristic bodily feelings. Again, traces left by former experiences will be excited, and this may give rise to images. More often it gives rise only to vague feelings of familiarity and to vague expectations. An example of what I mean is provided if rve see what looks like a heavy weightj but is really a hollow object made of skilfully painted cardboard. W e general l y do not have any dist inct im ages of what it rvould feel like to lift such a weight; still less do w e make expl i ci t j u dgm ent s about it s heaviness. But , if we start to lift it, we shall find that we have automatically adjusted our bodies as it would be reasonable to do if we had judged it to be heavy. And the feelings connected rvith this adjustment rvill be part of the total experience of external reference. When we start to lift it rve almost overbalance, and rve feel our expectations frustrated, though these expectations were not real l y present at th e t im e as dist inct belief s about t he future. I shall have to carry this analysis a little further

r54 MIND'S KNOWLEDGE OF EXISTENTS when I come to consider the subjective side of the perceptual situation, to which it more properly belongs. But it was necessary to ward off certain probable misu n d e r s t andings at o n c e . T o s u m u p : In a l l perceptual situations there is an external reference beyond the o b j e c t iv e c ons t it ue n t; a n d , i f y o u a s k e d th e ordi nary man to make this reference explicit, he would say that the objective constituent is literally part of a certain physical object of larger size and longer duration, which possesses many qualities beside those which are sensuously manifested to him in the perceptual situation. It is in virtue of this external reference that the perceptual situation has the epistemological object which it does have ; for the epistemological object just is this whole of which the objective constituent is believed to be a part. But it would be false psychologically to say that this belief is reached by a process of inference. For in fact we cannot detect any such process, and we ascribe perception to beings rvho would be quite i n ca p able of m ak in g i n fe re n c e s o f th e k i n d requi red. It would also be false psychologically to say that this belief exists at the purely perceptual level in the form of an explicit judgment I we must rather say that the percipient adjusts himself automatically in ways that would be reasonable if hp held this belief, and that th e b elief is r epr e s e n te d a t.th i s s ta g e b y t he bodi l y feelings which accompany these adjustments and by the feelings of satisfaction or frustration which arise according to the results of acting as if one held the belief. Lastly, it would be false as a matter of logic to maintain that this belief, in the precise form and in the actual strength in which it is held, could be justified by any knorvn process of reasoning from any available premises. So far we have used no argument which would not be equally valid if no perceptrral situations were in the least delusive. But of course it is held that there are delusive perceptual situations, and that in some cases

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the epistemological object is rvildly different from the ontological object. The drunkard says that he sees pink rats, just as the sober man says that he sees a penny. And the former means by " pink rats " something rvhich lasts beyond the duration of the perceptual situation, which could be felt as well as seen, rvhich could be seen and felt by other men, which rvould eat corn and excite fox-terriers, and so on. We call this perceptual si tuati on t'delusive, " because none of t hese expectations, rvhich form an essential factor in the situation, are verified by the contemporary perceptions of other observers or by the subsequent perceptions of the drunkard himself. We must remenrber that, although no amount of perceptual verification can prove that the objective constituent of a perceptual situation zs a part of a physical object of a certain speci fi ed ki nd, cornpl et e f ailur e of such ver if icat ion m ay make the contradi ctor y of t his alm ost cer t ain. lt m ay be doubtful whether there are such things as pennies, in the sense in rvhich the unphilosophical teetotaller asserts that there are I and it may be doubtful rvhether the objective constituent of the situation which we call " the teetotaller's perception of a penny " is literally part of a penny, as he believes it to be. But it is practically certain that there are no such things as pink rats, in the sense in rvhich the unphilosophical drunkard asserts that there are, rvhen he is in the situation called " seei ng pi nk rats." Now the existence of wildly delusive perceptual situations, such as rve have been describing, is important for our present analysis in several rvays : (,4 It supports the conclusion, rvhich rve have already reached independently, that language is a partly misleading guide to the analysis of perceptual situations. The perceptual si tuation, descr ibed as '( I am seeing a penny," does seem likely t o cont ain t he penny as a constituent if we follow the guidance of the phrase. We have already seen that this cannot be literally

156 MIND'S KNOWLEDGE OF EXISTENTS true, without needing to take into account the existence But this is more of delusive perceptual situations. glaringly obvious in the case of delusive perceptual situations. The drunkard says " I see a pink rat ", j us t as t he s o b e r ma n s a y s tt I s e e a b r ow n penny " ; and, mutatis mutandis, they mean exactly the same kind of thing by their two statements. So long as we follow the suggestions of language, there is just as much reason for holding that a pink rat is a constituent of the drunkard's perceptual situation as for holding that a brown penny is a constituent of the sober man's perceptual situation. But this analysis rnust be wrong in the former case, since there is almost certainly no And, since pink rat to be a constituent of anything. there is no relevant internal difference between the veridical and the delusive perceptual situation, it is reasonable to suppose that in no case does a perceptual situation contain as a constituent the physical object which corresponds to its epistemological object, even when there is such a physical object. (A) No doubt each perceptual situation does contain an objective constituent of a characteristic kind. And in each case this is bound up with the practical belief that this constituent is part of a larger and more enduring whole which possessescertain other qualities beside those which are sensuously manifested in the situation. The difference is that this practical belief, which goes beyond the present situation and its contents' is cerlainly wrong in the one case, whilst (so far as we ha're yet seen) it might possibly be right in the other. And there is absolutely nothing in the two situations as such to distinguish the case where the belief is certainly false from the case where it is possibly true. Now this cuts out an alternative rvhich rve have not yet refuted. We have indeed seen that the external reference of a per' ceptual situation cannot be regarded as a valid logical inference from the existence of the situation and the nature of its objective constituent. But, if there had

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been no delusive perceptual situations, the following al ternati ve mi ght have been m aint ained. I t m ight have been held that every perceptual situation is as such accompanied by an infallible revelation that its objective constituent is part of a larger and more enduring whole of a certain specific kind. All such si tuati ons certai n ly involve t his claim ; and, if t her e had been no reason to think that any of them are delusive, it might have been held that this is not a mere claim but an infallible reuelation. So far as I can see, such a position cannot be maintained in face of perceptions of pink rats. The clairn made here is of precisely the same kind as is made when teetotallers perceive pennies. And it is made just as strongly. Here the claim proves to be false. And, if it be false in soneecases, it cannot be accepted as true merely at its face-value in any case. Of course, if we water down the claim enough, it may at last be put in such an attenuated form as to be invulnerable to all refutation. If we claim merely that the objective constituents in all perceptual situations are correlated in some way with sotnet/ting larger and more enduring than themselves, and that every variation in the former is a sign of a change of some kind sontezthereor other in the latter, we can hardly be refuted. There is, no doubt, some such correlation between the objective constituent of the drunkard's perceptual situation and the alcohol in his stomach or something t hat is happening in his br ain. But I think it is perfectly clear that perceptual si tuati ons do i nvo lve a m or e specif ic claim t han t his; and that, si nce th is specif ic claim is cer t ainly wr ong in some cases and since there is no internal distinction between these cases and others, it may be wrong in all. The Alternatiue Theories. So far I have granted that, in some cases at least, the objective constituent cf a perceptual situation tnay in fact be literally a part of a larger external object of a certain specific kind, having other qualities beside those which are sensuously mani-

I5B MIND'S KNOWLEDGE OF EXISTENTS fested in the situation. I have shorvn only (a) that this o bjec t , as s uc h, i s n e v e r a c o n s ti tu e n t o f the si tuati on ; (b) that this claim can never be accepted at its faceva lue, bec ar r s eit i s c e rta i n l y s o m e ti me s fa l se i n si tuati ons rvhich dift'er in no relevant internal respect from those i n whic h it m igh t b e tru e ; a n d (e ) th a t th e cl ai m cannot be proved to be true, as it stands, by logical inference from any premises rvhich are available to us. It now remains to see whether we can hold that it is eaer true. Let us confine ourselves for the present to visual situations. I think we can prove that in this case rve a re t ied down to trv o a l te rn a ti v e s , n e i th er of w hi ch accords very well with common-sense. Either (a) the o b jec t iv e c ons t itu e n t o f a v i s u a l s i tu a ti o n does not have some of the properties which it seems on careful inspection to have, and does have properties inconsistent w it h t hes e ; or (b ) th e l a rg e r e x te rn a l w h o l e of rvhi ch i t is a part is so different from what it is commonly supposed to be that it hardly deserves the name of " physical object ". Of course it is possible that both a l ter nat iv es m ig h t h a v e to b e c o mb i n e d . Let us norv try to prove this. A penny is be l i e v e d b y c o m m o n -s e n s e to be a round flat object whose size and shape are irrdependent of the o bs er v er , his po s i ti o n , a n d h i s m o v e me n ts. A certai n o bs er v er m ay m o v e a b o u t, a n d m a y h o l d t hat i n al l the p er c ept ual s it ua ti o n s i n rv h i c h h e i s p l a c e d he sees the whole of the top of a certain penny. If he carefully i n s pec t s t he ob j e c ti v e c o n s ti tu e n ts o f th e se perceptual si tuat ions he r v i l l c e rta i n l y fi n d th a t th e y s eem to be of d i ff er ent s hape s a n d s i z e s . Mo s t o f th e m w i l l seem e l l ipt ic al and n o t ro u n d , a n d th e d i re c t i on of thei r major-axes and their eccentricity will seem to vary as he mo v es . Now, i f th e s e o b j e c ti v e c o n s ti tu ents are to be identified rvith different short slices of the history of the to p of t he penny , o n e o f tw o v i e rv s m u s t be taken. (a) One alternative is to suppose that these objective constituents realll, a7a all round and all of one size, although

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they seern,on careful inspection, to be elliptical and of vari ous si zesand eccent r icit ies. ( / ) The ot her alt er nat ive is to suppose that the penny is not of constant size and shape, as i s comm only believed, but t hat it var ies in these respects as the observer walks about. N ow the l atter a lt er nat ive m ight be t he r easonable one to take i f onl y one obser ver had t o be consider ed, and onl y hi s succe ssive visual sit uat ions. But in f acr there may be a number of obser ver s who can com par e notes. They may agree that they are all seeing the whole of the top of the same penny. And, as rve have sai d, i t i s certai nl y par t of t he not ion of a physical object that it is capable of being perceived by several observers at once. Now suppose that one of these observers stands st ill, whilst anot her m oves about . The objective constituent of the stationary observer's perceptual si tuati on rvill seem const ant in size and shape; the objective constituents of the moving observer's successive perceptual situations rvill seem to differ in size and shape. Evidently, if we suppose thar rhese objective constituents really do have the characteristics rvhich they seem to have ; that the observers really are seeing the rvhole of the top of the same penny ; and that the objective constituents of their respective perceptual situations really are identical rvith slices of the hi story of the top of t he penny, we shall have t o suppose that the penny both changes and keeps constant i n shape and si ze dur ing t he sam e st r et ch of t im e. And thi s seems at fi rst sight im possible. I f you give up t he view that two different observers can both literally see the same part of the same physical object at the same time, you have given up the neutrality and publicity which are part of the notion of a physical object. If you accept thi s publicit y and neut r alit y, and ident if y the objective constituents of the various visual situations rvith the neutral and public top of the penny, you must hold either (a) that the objective constituents have certain qualities which differ from and are inconsistent

160 MIND,S KNOWLEDGE OF EXISTENTS with those which they seem on careful inspection to have; or (/) that the top of the penny both varies and keeps constant in shape and size within the same stretch of time. The second alternative may seem impossible ; but let us not rashly reject it, since the first is not very much more attractive. A like result is reached if we consider a single observer in two different kinds of perceptual situation. A man may feel a penny, and at the same time move his head about whilst he continues to look at it. The objective constituent of the tactual situation seems on inspection to be constant in shape and size. Those of the successive visual situation seem on inspection to differ in shape and size. Now common-sense holds that it is the same surface which we see and which we touch ; though certain non-spatial qualities, such as colour, are sensuously manifested only in one kind of situation, whilst other non-spatial qualities, such as temperature, ale sensuously manifested only in another kind of situation. If we wish to keep the commonsense notion of physical objects, we n ust hold either (a) that the objective constituents of some perceptual situations have certain qualities which differ from and are inconsistent rvith those which they seem on careful inspection to have ; or (b) that one and the same surface can vary and keep constant in shape and size within the same stretch of time. I think that I have now proved that we are tied down to three alternatives, each almost as distasteful to common-sense as the others. (a) We may try to keep the common-sense view that the objective constituents of some visual situations are literally spatio-temporal parts of a certain physical object, which we are said to B ut , i f w e d o th i s , w e mu s t h o l d ei ther be "se eing' . ' . (c) that this physical object can be both constant and variable in its spatial characteristics within the same stretch of time ; or (p) that the objective constituents of the visual situations can have qualities which are

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different from and inconsistent with those rvhich they seem on careful inspection to have. Or (b) we may drop the common-sense view that the objective constituent of a visual situation may be, and in some cases actually is, literally a spatio-temporal part of a certain physical object which we are said to be " seeing ". I rvill norv take these alternatives in turn. (a, a) T/zeory of Multiple fnlterence. It might be held that this alternative is so absurd that it is not worth discussing. Is it not a plain contradiction that the same part of the same thing should be at once variable and constant i n si ze, ro und and ellipt ical, and so on ? It seems to me that this is possible, if and only if what we commonly regard as pure qualities are really relational properties. We all know that the same man can be at the same time generous (to his family) and stingy (to hi s w orkmen). The only quest ion is whet her we could possi bl y deal w i th such p r oposit ions as 'r This is r ound ", " This is elliptical ", etc., where " This " is an objective consti tuent i n a vi sual s it uat ion, in a sim ilar way. 'Let us first state what characteristics the objective constituent of a visual situation seems on careful inspection to have. I think we may fairly say that it seems to be a spatially extended patch, having a'certain determinate size and shape, situated in a certain determinate position out from the body, and norv occupied and marked out by a certain determinate shade of a certain colour. Of course, the colour need not be uniform throughout the region ; but this raises no question of principle, so I w i l l assume for si mpl i ci ty t hat it is unif or m . We have then four things to consider : the apparent colour, the apparent shape and size, the apparent position, and the apparent date at which the colour inheres in the place. Now it has been suggested that the objective constituent of a visual situation can be regarded as a certain region of physical space which is pervaded by a certain determinate shade of colour at a certain time, prouided tlmt we recognise that the relation of " per-

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It must not be a two' vasion " is of a peculiar kind. p e rv a d i n g col our and r elat ion, inv o l v i n g th e te rm only the pervaded region, as 1ve commonly suppose. It must be at least a three-term relation, involving the pervading colour, the pervaded region, and another region which we might call the " region of projection ". Theories of this kind have been suggested lately by Dr Whitehead and by Professor Kemp Smith ; and it seems to me that such a theory in a very crude form may be detected by a very charitable interpreter in the writings of Malebranche. I propose now to discuss it in my own way rvithout further reference to the eminent men rvho have suggested it. I rvill call this type of theory " The Theory of Multiple Inherence ". The impression which it makes on me at the outset is that it can be made to rvork very well for secondary qualities, like colou?, provided we raise no questions a b out s hape, s iz e , p o s i ti o n , a n d d a te ; b ut that i t i s more difficult to deal with these apparent characteristics of the objective constituents of perceptual situations in terms of the theory. Let us begin with colour. According to the theory the proposition " This is sensibly of such and such a shade of red " (where (' this " is an objective constituent of a visual situation) could not be true if " this " were the only thing in the rvor ld, any m or e th a n ' { T h i s i s a s h a re h ol der" coul d b e t r ue if ' ( t his " w e re th e o n l y th i n g i n the w orl d. ( ' c ould u o t" h e re I me a n , n o t m erel y An d by that i t is causally impossible, but also that it is logzcally impossible. Red, on the present view, is a characteristic o f s uc h a k ind th a t i t c a n n o t i n h e re i n a p l ace si mpl y; it can only " inhere-in-a-place-from-a-place ", and this relation, which needs such a complex phrase to express it, is simple and unanalysable. Norv, supposing that this u'ere true, it would be perfectly possible that one and the same region of physical Space should be pervaded at one and the same time by different determinate sh a des of r ed. F o r th e mi n i mu m c o mp l e te statement

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abor.rt pervasion by a colour would be of the form : " The determinate shade r, inheres in the place s from the place s, at the time I ". And this is perfectly compatible rvith : " The determinate shade r, inheres in the place s from the place s, at the time /". What u,ould be inconsistent with the first proposition is the proposition : " The determinate shade z, inheres in the pl ace s from the pl ace s, at t he t im e 1". But t her e is no reason to suppose that this complication ever arises, so it need not trouble us. It would now be perfectly easy to define a meaning for the phrase "s zi red" without reference to any other parti cul ar pl ace. We m ight , €. 5. t def ine "s zs r ed" to mean " From euery place sonrc shade of red inheres in .r ". This is no doubt only a first approximation to a satisfactory definition. For '( every place " we should certainly have to substitute " every place that fulfils such and such cond it ions ". But t he gener al pr inciple of the defi ni ti on i s o bvious enough, and I do not t hink that there rvoul d be m uch dilf icult y in m ent ioning t he condi ti ons. The full st at em ent r vould not , I t hink, di ffer very much from t he f ollor ving: - t t s is physically red " means " From every place which is physically occupied by a normal human brain and nervous system i n a normal condi ti o n and is near enough t o s som e shade of red sensibly inheres in s." The first condition is put in to deal with colour-blind men and men drugged w i th santoni n ; the s econd is put in t o cut out com plications about coloured spectacles, and so on. The essence of the theory, so far as we have gone, i s thi s :. W e must dist inguish bet ween t he " sensible " and the " physical " inherence of a colour in a place. The former i s the fun dam ent al and indef inable r elat ion ; and i t i s i rreduci bly t r iadic, involving an essent ial reference to the pervading shade of colour, the pervaded regi on, and the regi on of pr oject ion. The lat t er is a two-term relation : but it is not ultimate. for it is defin;rbl e i n terms of the for m er . And t he def init ion is of t he

164 MIND'S KNOWLEDGE OF EXISTENTS following kind: "R inheres physically in s" means " From every place s,, which fulfils certain conditions C, some determinate form r,, of the determinable R With these definitions we sensibly inheres in s ". maintain the common-sensevierv perfectly well could two different colours have that a physical object cannot at once,and yet admit that it does have different colours at once. We should simply need to clear up the ambiguities of our statements. The truth will be (I) that two different colours cannot sensiblyinhere in the same place from the samey'laceat once; (z) that two different colours cannot physically inhere in the same place at once; but (3) that different coloursor different shadesof the same colour can sensiblyinhere in the same place from diferent places at once. Perhaps I ought to say a word or two in further explanation of the second of these propositions. To say that the same place was at once physically red and physically green rvould be to say that from every one of a certain set of places this place was sensibly pervaded by some shade of red, and that from every one of the same set of places it is at the same time sensibly pervaded by some shade of green. This, I suppose,would be admitted to be impossible. But it does not cover all that we mean when we say that the same place could not at once be physically pervadedby two different colours. Under this head we should also includEt €.t.t two different shadesof red as well as two different colours, such as red and green. This, however, raises no insuperable difficulty. We have defined the physical colour of a place in terms of the colourunder which all the determinateshadeswhich sensibly inhere in it from a certain set of places fall. It rvould be quite easy to define its physical shadein a similar way. We should say that a certain place was physically pervaded by purple if and only if all the shades rvhich sensibly inhere in it from places which fulfil the required conditions fell within certain limits. If we rvere prepared to say that this place is physically

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pervaded by scarlet it is certain that it rvould have to be sensibly pervaded from the sane ptaces by diferent shades of red. Since it could not be sensibly pervaded at the same time and from the same place by different shades of the same colou r any more tiran by shades of different colours, it rvould be impossible for it to be at once physically pervaded by scarlet and by purple on our definitions. So far we have been discussing a question which may be cal l ed (' l ogi cal " , in a wide sense, and cer t ainly not B y thi s I m ean t hat we have sim ply been " causal " . consideringthe question : ..What formal characteristics must the relation of inherence possess if it is to be logically possible to hold that a number of different colours or shades of colour inhere at the same time in the rvhole of the same region of Physical Space ? " The causal questi on i s: ,. Under what condit ions r vill such and such a colour inhere in such and such a place from such and such a pl ace?" To t his quest ion I now t ur n. In view of what we know of geometrical and physical optics and of the physiology of vision, I think that the following answer is alrnost certain. The independently necessary and sufficient nnterial conditions for a certain shade of colour to pervade a certain external region from a certain region of projection are all contained in or are close to the region of projection. (I rvill explain i n a moment w hy I i nt r oduce t he qualif icat ions which I have italicised.) The direction of the pervaded region is the direction in which a normal human being, ruf,o." body is in the projecting region, has to look, in order to get the objective constituent under consideration into the mi ddl e of hi s vi sual f ield ; and t his is knor vn t o depend si mpl y on w h at is going on in t he im m ediat e nei ghbourhood of hi s e yes. When a num ber of people are sai d to be .,seei ng t he sam e object dir ect ly und". rrormal condi ti ons" , i . t . , wit hout com plicat ions due t o rnirrors, non-homogeneous transparent media, and so on, their respective lines of sight intersect within a

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This is where the fairly small determinate region. object is then said to be. But of course there often are m i rro rs and ot her c o m p l i c a ti o n s , a n d w e m ust be prepared to deal u'ith the general case. When the me d i u m is in f ac t no n -h o m o g e n e o u s ' o r th e v i si on i s indirect, the place which is pervaded by a given shade of colour from a given region of projection is that place in which a suitable object ruould have to be put in order to present the same appearance if viewed directty and In actual fact through a homogeneous medium. n o th i n g phy s ic ally r e l e v a n t ma y b e g o i n g o n i n thi s region ; this is the case rvith mirror images. If I look at the reflection of a luminous point in a plane mirror the region which is pervaded from rvhere I am standing is so mer v her ebehind th e m i rro r ; i t i s th e p l a c e w here a lu mi n o u s point would h a v e to b e p u t i n o rd e r to present t h e a ctual appear ance , i f v i e w e d d i re c tl y a n d rvi thout a mirror, from where I am standing. And of course no th i n g phy s ic ally r e l e v a n t i s h a p p e n i n g a t th i s pl ace The direction of the place is behind the mirror. d e te rmined by t he d i re c ti o n i n w h i c h th e l i g ht enters my e ye, i. e, , by ph y s i c a l e v e n ts i n th e i mmedi ate neighbourhood of the region of projection. Its distance along this direction is presumably determined by traces left in my brain by past visual situations and correlated bodily movements in cases rvhere the vision really rvas d i re ct a nd t hr ough a h o m o g e n e o u s me d i u m . Thus I am justified in saying that the position of the pervaded re g i o n is im m ediat el y d e te rm i n e d b y e v e n ts i n or cl ose to the region of projection. Next, the facts which make us ascribe a velocity to light, and particularly the fact of aberration, make it almost certain that the date at which a certain place is pervaded by a certain shade of colour from a certain region of projection is the date at which certain events a re h a p pening wit hin th e re g i o n o f p ro j e c ti o n . W hen I look at a distant star a certain shade of colour sensibly inheres in a certain distant region of Physical Space

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from the place which is physically occupied by my body, if the present theory be true. But rve know quite well that the star may no longer be physically occupying this distant region ; and that, whether it does so or not, the relevant physical events may have happened there hundreds ofyears ago. Lastly, and in close connexion with this, we must notice that the particular colour and the particular shade of i t w hi ch sensi b ly per vade an ext er nal place from a region of projection are almost certainly determined by specific events in the eyes, optic nen'es, and brain which now physically occupy this region of projection. Facts about colour-blindness, about the effects of drugs l i ke san t onin, and of m or bid bodily states l i ke j aundi ce, make t his pr act ically cer t ain. I have now defended the statement that the independently necessary and sufficient nmterial conditions w hi ch determi ne that such and such an ext er nal place shall be pervaded by such and such a shade of colour from a certain region of projection are physically present within or close to that region. I will now expl ai n w hat I mean by t he it alicised qualif icat ions in thi s statement. (r) The physical event s wit hin t he region of projection of course have physical causes. Now a necessary condition of a necessary condition of an event may be cal l ed a t 'dependent ly" necessar y There is every reason to condition of that event. believe that the pervasion of a certain region from a certain region by a certain shade of colour has generally dependentlynecessary conditions rvhich are quite remote from the region of projection. When a certain place is pervaded by very similar shades of the same colour from all directions it is generally found that, on walking up to this place, tactual situations arise. And the objective constituents of these tactual situations are generally found to be closely correlated with the objective constituents of the successive visual situations which occur as we walk up to this place. We

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s ay t hen t hat t h i s p l a c e i s r(ta c tu a l l y o c cupi ed" . A nd lve have very good reason to believe that such a region is physically occupied by certain microscopic events which are remote and dependently necessary conditions of the pervasion of this region by such and such a shade of colour from places round it. These events determine by physical causation certain events in our eyes, optic nerves, and brains; and the latter events are the immediately necessary and sufficient material conditions of the pervasion of the external region by such and such a shade of colour from the region of projection which contains our bodies. This may be regarded as t he nor m al c a s e ; a n d i t i s e x p re s s e d i n common language by saying that we are then " looking directly at a certain physical object through a colourless homogeneous medium ". But of course this sweet simplicity, S u ppose that a t hough nor m a l , i s n o t u n i v e rs a l . n um ber of peo p l e t' s e e th e s a m e mi rro r i mage " . Then there is a certain set of microscopic physical events in a certain region of Space ; and these do constitute the common dependently necessary condition of the pervasion of a place behind the mirror by similar shades of the same colour from a number of different regions But the region rvhich contains these of projection. physical microscopic events is remote from the region in whic h t hes e s h a d e s o f c o l o u r s e n s i b ly i nhere; i t i s in fact as far in front of the tnirror as the pervaded region is behind it. Let us call the region which contains the common dependently necessaryconditions " the emitting region ". Then the position may be put as follows: In visual perception we have to consider an emitting region, a region of projection, a pervaded region, and a perThe pervaded region is imvading shade of colour. by events in and near the region determined mediately d e te rmi n e i mmedi atel y e v e n ts a l s o of pr ojec t ion. T h e s e the pervading shade and colour. And they are themselves determined by microscopic events in the emitting

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region. In the cases that arise most often in everyday practical life the pervadeC region and the emitting region roughly coincide. But, in the case of mirrorimages and the visual situations which arise when we are surrounded by non-homogeneous media, the pervaded region and the emitting region cease to coincide and may be very distant from each other. The pervaded region may then contain no physical events at all ; and, if it does, they will be quite irrelevant. In such cases there will always be a purely optical peculiarity too, viz., that the pervaded region will never be pervaded from all directions by similar shades of the same colour. (Cf. the sudden change which happens in the visual situation when we go to the back of a mirror in which rve have been viewing the image of a certain object.) Just as we have contrasted the pervaded region and the emi tti ng regi on, so we m ust cont r ast t he "dat e of pervasion " and the " date of emission ". Owing to the very great velocity of light these generally coincide almost exactly in the visual situations of ordinary life. But, rvhen we are concerned with very remote objects, such as stars, the date of emission (which is alzuaTs earlier than the date of pervasion) may precede the latter by thousands of years. In the phenomenon of aberration we have a most interesting case in rvhich the motion of the observer of a very distant object, and the difference between the date of emission and the date of pervasion, cause a difference between the llace of emission and the placa of pervasion. (z) I have norv explained why I used the phrase " independentlt necessary and sufficient conditions ". It rcmains to explain why I introduced the word ..ttaterial" before " conditions " in my original statement. This was simply a precaution. I cannot be completely r:ertain that the sensible inherence of such and such a shade of colour in such and such a place from a given lcgion of projection ,naJ/not have psychical as well as l rl rysi cal condi ti on s. Since we cannot get a br ain and

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ne rvo u s s y s t em lik e o u rs w o rk i n g p ro p e rl y w i thout a m i n d l ik e our s , it is o b v i o u s l y i mp o s s i b l e to be sure th a t th e lat t er is ir r ele v a n t fo r th e p re s e n t p u rpose and that the former is sufficient by itself. And, beside this general consideration, there is a more specific ground fo r ca u t ion. I do n o t th i n k th a t th e d e te rmi n ati on of the position of the pervaded region can be completely explained rvithout reference to the persistent effect of pa st vi sual and t ac t ua l s i ttra ti o n sa n d b o d i l y m o vements, a n d th e as s oc iat ion s b e tw e e n th e m . N o w o f course these factors ttm)' now be represented simply by persi ste n t and s uit ably li n k e d m a te ri a l mo d i fi c a ti o ns i n the b ra i n a nd ner v ous s y s te m . B u t, o n th e o n e h a n d, these material " traces " are purely hypothetical effects of c e rta i n c aus es and c a u s e s o f c e rta i n e ffe c ts . And, on th e o th e r hand, ev en i f th e y b e n o z ap u re l y m a teri al , i t may be that they could not have been formed originally rvi th o rr t t he ac t ion of th e mi n d . a t l e a s t i n th e form of se l e cti v e at t ent ion. If th i s b e s o , w e mi g h t s ti l l say that the independenily necessary conditions fora certain colclur to pervade a certain place from a given region of proj e cti o n ar e all m at er i a l I b u tw e s h o u l d h a v e to re cogni se that the past action of the mind is a dependentlynecessary co n d i ti o n, jus t as m u c h a s th e p a s t v i b ra ti o n s of di stant el e ctro ns . So far t he T heor y o f M u l ti p l e In h e re n c e seems to have rvorked fairly well. But we have left to the end th e h a rdes t ques t ion w i th rv h i c h i t i s fa c e d . T h i s i s the q u e sti o n of " phy s ic a l " a n d (' s e n s i b l e " s h a p e a nd si ze. We know that different observers, who say that they a re a l l s eeing t he wh o l e o f th e to p o f th e s a m e penn/, fi n d o n c ar ef ul ins pe c ti o n th a t th e s h a p e s a n d si zes of th e o b jec t iv e c ons ti tu e n ts o f th e i r re s p e c ti ve vi sual s i tu a ti ons s eem t o b e d i ffe re n t. W e k n o w that the s a me com plic at ion a ri s e s i f a s i n g l e o b s e rv er moves ab o u t r v hils t he c la i ms a l l th e ti me to b e s e ei ng the whole of the top of the same penny. And rve know that it also arises when the same observer claims to be

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at once seei ng and touching t he whole of t he t op of t he same penny. W e have dealt wit h sim ilar dif f icult ies about shades of colour by suggesting that the relation of i nherence betw een a colour and t he place which it pervades i s i rreduci bl y tr iadic, and not dyadic, as has commonl y been thought . But can we possibly deal rvith the difficulties about shape and size in the same w ay ? C uri ousl y enough, Dr Whit ehead does not , so far as I know , di scuss this point . Yet no t heor y can cl ai m to be sati sfactory r vhich does not m ake som e answ er to the questi on. A t fi rst si ghrt i t seems evider r t t hat we cannot deal rvi th vari ati ons i rr the ap par ent shape of t he sam e sur face in the rvay in rvhich rve have been dealing with vari ati ons i n i ts apparent colour . I t seem s obvious t hat tlre proposition " This is round " coulcl have been true, even i f there had been not hing in t he wor ld but t his area. In fact the shape of a region seems to be an i ntri nsi c qual i ty of i t; an d it seem s nonsense t o t alk of vari ous shapes i nheri ng i n a cer t ain r egion f r om var ious pl aces. P l ausi bl e as this ar gum ent sounds, I believe that i t i s mi staken. I think t hat it over looks a ver y i mportant di sti ncti on, viz. , t he dist inct ion bet ween a I " sensi bl e form " and a " geom et r ical pr oper t y ". shall lirst try to explain the difference betrveen the trvo, and to shorv that they must be dist inguished quit e apar t from the present probl em. And I shall t hen t r y t o shorv that the di sti ncti on enables us t o apply t he I\{ ul ti pl e Inherence Theor y t o t he quest ion of var iat ions o[ apparent shape and si ze. Let us consi der ci rcular it y, f or exam ple. I f ind it ncoessaryto di sti ngui sh a cer t ain geom et r ical pr oper t y r:rl l ed " ci rcul ari ty " and a cer t ain sensible f or m called l ry the same name, for t he f ollor ving r easons. The gcometrical property can be defned. 'lo say that a ct.rt:ri narea i s geometri c ally cir cular lnedilst hat all t he poi rrts on i ts boundary ar e equidist ant f r or n a f ixed poi rrt. B ut, i f I rvanted t o m ake som eone under st and

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what I was referring to by the phrase " sensibly circular ", it would be of no use whatever to offer this d ef init ion or any o th e r d e fi n i ti o n . A l l th a t I coul d do would be to proceed by eneilzpbrtcailon,just as I should have to do if I wanted to make him understand what I am referring to when I use the word " red ". I should in fact have to proceed as follows : I might start by getting the man to look straight down on to a penny. I should then cut out geometrically circular bits of paper of various colours and sizes and get him to look straight dorvn on them. I should also cut out bits of paper of the same colours and different geometrical shapes, and get him to look straight down on them. I should then say to him : " You notice that there was a certain resemblance between all the objective constituents of the first series of visual situations in which I placed you, in spite of the differences of colour, etc. And you notice that there was a certain unlikeness between every objective constituent of the first series of visual situations and every objective constituent of the second series. Very well ; what I am referring to by the phrase " circular sensible form " is that feature rvhich was present in all members of the first series and a b s ent in all m em b e rs o f th e s e c o n d ." In my vi ew i t i s just as impossible to know a priori that a geometrically circular area, when pervaded by a colour and viewed normally, would have the sensible form called " circularity " as it is to know a lriori that an area containing electrons moving in a certain rvay would be pervaded by a certain shade of red from a place occupied by a normal human body. Of course some geometrical properties are themselves indefinable; €.{.t geometrical straightness. But it remains a fact that all sensible forms are indefinable, whilst manJ/ of the geometrical properties which are called by the same name are definable. It is therefore certain that geometrical properties and the sensible forms which are called by the sa m e nam es m us t b e d i s ti n g u i s h e d .

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Let us now apply this conclusion to our present problem. When it is said that the shape of a region is an intrinsic property, and that it is nonsense to talk of it having such and such a shapefrom such and such another region, this is true only of geometrical shape. If an area is geometrically circular it is so intrinsically, and there is an end of the matter. But, since geometrical shape and sensible form must always be distinguished, it does not follow that the sensible form of an area is an intrinsic property of it. It may be that one and the same a r ea is t . inf or m ed " by one sensible form from one place and by a different sensible form from another place. The relation of .. informing " be irreducibly triadic, as 1ve have suggested that ^^y the relation of " pervading " is. If this be so, it may be that it is only from one place or one series of places that an area with a certain geometrical shape is informed by that sensible form rvhich has the same name as the geometrical shape. A like distinction will have to be drawn betrveen geometrical and physical size. The geometrical size of a region will be an intrinsic property of it ; but the sensible size may be a property which it only has from another region. It rvill of course be just as necessary to distinguish tactual form from geometrical shape as to distinguish visual form from geometrical shape. But there may be good reasons for holding that tactual form is a safer indication of geometrical shape than is visual form. There is every reason to believe that the visual form which informs a certain external region from a certain region of projection is causally determined by events which are physically contained within the region of projection. The determining factors rvould seem to be the geometrical shape and size of the part of the retina affected by light, and traces in the brain and nervous system left by past visual and tactual situations. Here again it seems to me that rve cannot be sure that the rni nd does not pl ay an essent ial par t , if not as an inde-

r74 IVIIND'SKNOWLEDGE OF EXISTENTS pendently necessary condition, yet perhaps as a remote and dependently necessary condition for the original formation and association of the traces. I have now sketched and defended to the best of my a b i l it y t he M ult ip l e In h e re n c e T h e o ry . It i s ti me to ask o u rs elv es : " Hor v m u c h o f th a t p ri m i ti v e b el i ef w hi ch is an essential part of every perceptual situation would Under be left standing if rve accepted this theory?" favourabl e ci rcu m stanc es,i.e.,when we should com monly be held to be seeing a not too distant object by direct vi si on t hr ough a c o l o u rl e s s h o m o g e n e o u s m edi um, w e could go thus far rvith common-sense. We could hold (I) t hat t he v is ua l s i tu a ti o n s o f a n u m b e r of observers rvho say that they are seeing the same object really do co n t ain a c om m o n o b j e c ti v e c o n s ti tu e n t, v i z., a certai n region of Space outside their bodies. (z) That this same region of Space is the common objective constituent of the visual and tactual situations of an observer who would be said to be seeing and touching the same object. (g) That this region really is pervaded norv by those sensible qualities and informed by those sensible forms which each observer can detect by careful inspection in the objective constituent of his perceptual situations. (+) That this region really does physically contain a set of microscopic physical events (movements of molecules, vibrations of electrons, etc.) which are the dependently necessary conditions for the pervasion of this region by these sensible qualities from the places now occupied by the observers' bodies. This is as far as we could go in a g re em ent wit h c o mmo n -s e n s e . W e s h o ul d have to differ from common-sense, even in the cases rvhich are mo s t f av our able to i ts b e l i e fs , i n th e fo l l o w i ng poi nts: (r) I t believ es t h a t th e c o l o u rs w h i c h i t s e esare qui te literally spread out over the surfaces of thephl,sit'al objects which it sees and touches. ln view of the facts about mi rror - im ages , etc ., w e c a n a d mi t o n l y th a t col ours pervade certai n regiotts of Space. The latter may or may n o t c ont ain t hos e m i c ro s c o p i c p h y ' s i c a l th i n g s and events

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rvhich afe the dependently necessary conditions of the pervasi on of thi s region by t his colour . Even when thi s i s so, i .e., w hen t her e is an em it t ing as well as a pervaded region and the trvo coincide, we cannot say that the microscopic events and objects have the colour I we can say only that the region which contains them is pervaded by the colour. (z) Common-sense believes that the pervasion of anything by a colour is a twoterm rel ati on betrveen t his t hing and t his colour . I n vierv of the fact that the rvhole of the top of the same penny may appear brorvn to me and yellorv to you, who have taken santonin, \f,'ecannot admit this. If rn'ervish to hold that this one surface really is the common objective constittrent of your visual situation and of mine, and that it really has the colours which it seems to you and me on careful inspection to have, we must hold that the sensible pervasion of a region by a colour is at least a three-term relation. It must involve an essential reference to a region of projection as well as to the pervaded region and the pervading colour. (S ) C ommon -sense believes t hat t he independent ly necessary and sufficient conditions for the pervasion of a certain region by a certain colour are contained in that region at the time when it is pervaded by this colour. It therefore holds that this region would be pervaded by this colour at this moment no matter rvhat might be going on elservhere. This cannot be 'Ihe independentfi, necessary and sufficient accepted. conditions for the pervasion of a certain region by a certain colour are neuer contained in the pervaded region and are alutays contained in or near the region of projection. It is true that, in favotrrable cases, the dependently necessary conditions for this pervasion rnay haz,e been contained in the pervaded region viz., 1 rvhen there i s an emi tt ing r egion and it coincides r vit h the pervaded regi on. But , in t he f ir st place, t her e m ay l rc no emi tti ng regi on at all. ( Cf . t he visual sit uat ioni of dreams, or the case of t he dr unkar d and his pink

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rats.) Secondly, there may be an emitting region, but it may be quite remote from the pervaded region. (Cf. mirror-images and aberration.) And lastly, even rvhen there is an emitting region and it coincides with the pervaded region, common-sense is always wrong about the date of the relevant physical events in this region. It always assumes that they are contemporary with the pervasion, whereas they are always earlier and may be earlier by thousands of years. The net result of all this is that there is the strongest reason to believe that no region would be pervaded by any colour unless so m e ot her r eg i o n c o n ta i n e d a l i v i n g b o dy rvi th a sui table brain and nervous system functioning properly. To t he ques t io n : " Are th i n g s re a l l y c ol oured?" w e can make the following answers on the present theory. (i) Colour is not logically an intrinsic quality of anyIts nature is such that it can pervade one place thing. only from another place. We may express this by saying that it is a genuine characteristic, but that it i s a t t m ult iply -i n h e re n t" o n e . ttT o b e col oured" i s a characteristic which is logically of the same kind as " to be envied." (ii) Things are not coloured, in the sense that their colour is a primitive and causally independent characteristic of them ; or in the sense that it is directly determined by their intrinsic characteristics. The colour which pervades a region is directly determined, not by the physical contents of that region, but by the physical contents of a different region. A certain region really is pervaded by a certain colour from a certain other region if and only if the latter contains a suitable brain and nervous system, functioning properly. I express this fact by saying thar the colour of a region from a place genuinely pervades it, but is " causally adventitious " to it. (iii) A region may contain such microscopic physical events and objects that a certain shade of a certain colour would pervade it from any region which is near enough, y'the latter were occupied by a normal brain and nervous system in

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normal working order. I express this by saying that thi s regi on has suc h and such a . , pot ent ial colour . " (iv) If it be asked whether my previous statements imply that col ours are ttmi nd- dependent ", I answer as f ollows. The pervasion of a certain place by a certain bolour from a certain region of projection is not dependent cln this col our bei ng perceived by t he m ind which anim at es the organism that occupies the region of projection. Nothing depends for its existence on being perceived. But it is conceivable that the same events in the brain and nervous system have trvo effects, viz., that they cause a certain distant place to be pervaded from the region of projection by a certain colour, and that they cause the mi nd w hi ch anim at es t he or ganism in t he region of projection to perceive this colour. If this were so, the colour could not pervade the external place from the region of projection without being perceived by the mind which animates the organism in the region of projection. But it seems to me most unlikely that the bodily conditions which cause the colour to inhere are identical with the bodily conditions which cause the mind to perceive ; and there is certainly no evidence for such a view. If the two sets of conditions be not identical, it is logically possible that a colour should pervade a place from a region of proj ecti on w i thout bei ng per ceived by t he m ind which animates the organism in this region of projection. Whether this in fact ever happens is a question to be decided by empirical considerations. We must remember, however, that a colour might be in part minddependent w i thout b eing dependent on t he par t icular rnental event of being perceived. As I have said, it seems to me likely that some of the remote conditions of the characteristics of the objective constituents of visual situations are mental ; and it is quite possible that some of thei r i mmediat e condit ions ar e also m ent al. It is, e.g., quite arguable that the sensible form and size and distance of objective constituents is in part

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d e t er m ined by o u r p re d o m i n a n t i n te re s ts and bel i efs a t t he m om ent . I t is ev ident , th e n , th a t th e T h e o ry o f Mul ti pl e Inherence, though it allows us to keep some parts of the primitive belief which is part of every perceptual situation, requires us to modify other parts very profoundly in the case of visual situations. We shall find that the other alternatives are equally upsetting to c om m on- s ense . T o th e rn I n o w tu rn . I shall (a, B) Multiple Relation Tlteory of Appearing. be able to deal much more briefly with this and the third alternative, because I have brought out in the last section most of the important facts which must be recognised by any satisfactory theory. On any theory we must recognise that the independently necessary and sufficient conditions of the apparent characteristics of the objective constituents of perceptual situations are contained in or near the place occupied by the percipient's body ; that there may be no external emitting region ; that, if there is one, it may be remote from the region which these characteristics apparently pervade ; and that, even if the trvo regions coincide, the date of apparent pervasion is later than the date of emission. There is a close formal analogy between the present theory and the one discussed in the last section. Both o f t hem hav e t o a s s u m e a fu n d a m e n ta l re l ati on w hi ch i s a t leas t t r iadic . T h e Mu l ti p l e In h e re n c e Theory supposes that colours inhere triadically in places from places ; and that sensible forms triadically inform regions from regions. The Multiple Relation Theory o f A ppear ing as s u me s th a t, i f a c o l o u r re a l l y di d i nhere i n any t hing, it w o u l d i n h e re d y a d i c a l l y , as commonsense supposes. But it assumes a fundamental relation of " appearing ", which must be at least triadic. Thus it assumes, as logically possible, two different kinds of proposition about characteristics like colour, shape, etc. One is of t he f o rm " T h i s z s re d " I th e o ther i s of the form " This loohs red from here ". And. in order to

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deal with the known facts, it has to assume that the objective constituent of a visual situation can seem from a place to have characteristics which are other than and incompatible with the characteristics which it does have. If the top of a penny literally has a certain col our dyadi cal l y, i t can have only one shade of one col our. B ut i t cert ainly seem s t o have a num ber of different shades of the same colour, and may even seem to have a number of different colours, from different places occupied by different observers. Hence, if a penny l i teral l y and dyadically possessesa colour , t he colour which it /tas must differ from all but one of the colours or shades which it seens to have ; and, it may di ffer from al l of the m . Whilst , if it does not lit er ally and dyadi cal l y posse ssany colour , it is st ill plainer t hat i t seems to have ch ar act er ist ics which it does not in fact have. The same remarks apply to shape, size, and ;l osi ti on. On thi s theor y t hen we m ay be acquaint ed in a perceptual situation with a spatio-temporal part of a certain physical object which we are said to be perceiving. But rve learn only about the characteristics rvlrich it seens to have; and the more carefully we inspect the obj ecti ve co nst it uent t he m or e we lear n of it s a?farent properties only. And it is certain that it either does not actually haue properties of this kind at all ; or that, if it does, the apparent and the real properties can be identical only in one specially favoured perceptual situation. And there is of course nothing in any particular perceptual situation, taken by itself, to tel l us that i n i t and it alone t he appar ent and t he r eal t:haracteristics of the objective constituent are identical. Let us now consider the points of difference betrveen thi s theory and the one which we discussed bef or e. l l oth theori es al l ow t hat , under suit able condit ions. it rnay be true that there is a com m on object ive const it uent to the vi sual si tuati o ns of a num ber of obser ver s who sa.1' that tl rey are ,,seeing t he sam e object ". Bot h ;rl l < nvthat there i s, under suit able condit ions. a com m on

I8O MIND,S KNOWLEDGE OF EXISTENTS objective constituent to the visual and the tactual situations of an observer who says that he is " seeing and And both allow, that, under feeling the same object". suitable conditions, this common objective constituent may be literally a spatio-temporal part of the object which the various observers say that they are " seeing a n d f eeling " . B u t, a t th i s p o i n t, e a c h h a s to di verge The from common - sense in a different direction. the objective that allows Theory Inherence Multiple constituent really does have those characteristics which it seems on careful inspection by each observer to have' But it can allow this only by supposing that these characteristics inhere in the objective constituent in a way never contemplated by common-sense, viz., triadica l l y. T he M ult i p l e R e l a ti o n T h e o ry o f A ppeari ng allorvs that, if the objective constituent did have such characteristics as it seems to have, they zuoulrl inhere in it in the ordinary dyadic way which commoll-sense re cognis es . B ut i t c a n a l l o w th i s o n l y b y supposi ng that most, if not all, of the determinate characteristics which the objective constituent seems on careful inspection to have do not in fact inhere in it. And both theories, as I have said, have to depart altogether frorn common-sense when they pass from purely logical to ca u s al c ons ider ati o n s . T h e c o n d i ti o n s w h i ch i mmedi -

not in or near the place where the objective constituent es on the first theory or seertts to be on the second' And the remote and dependently necessary conditions, in many cases' are neither in nor near the tatter place' (h) The Sensuttt' Theorlt. Poor dear Common-sense has not done very rvell out of the two types of theory Let which $'ere constructed for its special benefit' u s now c ons ider th e th i rd p o s s i b l e a l te rn ati ve' Thi s theory allows that the objective constituents of per-

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ceptual si tuati ons re ally do have all t hose posit ive characteristics which they seem on careful inspection to have. A nd i t al l ows t hat t hese char act er ist ics inher e in these objective constituents in the straightfonvard dyadic rvay in which common-sense supposes them to do. B ut, i n admi tti ng t his m uch, it is t hen f or ced to depart from comm on- sense. I t cannot adm it t hat the vi sual si tuati ons of a nr r m ber of obser ver s, r vho say that they are ,,se eing t he sam e object ", cont ain a common obj ecti ve const it uent . I t cannot adm it t hat , w hen a man says that he is , , seeing and f eeling t he same obj ect" , there i s in gener al a com m on object ive consti tuent to hi s vi s ual and his t act t r al sit uat ions. And it cannot admit that, rvhen we say that rve are " seeing a certain physical object ", the objective consti tuent of our vi sual sit uat ion i. s in gener al a spat iotemporal part of the physical object rvhich rve say that rve are " seei ng" . On t his t heor y, t her r , t he object ive consti tuents of most, if not all, per cept ual sit uat ions canuot be spatio - temporal parts of physical objects. No doubt they are really extended ; they really last for so l ong; they re ally have ccr t ain shapes, sizes, col ours, etc.i and some at least of t hem st and in spat ial and temporal rel ati on s t o each ot her . But t hev ar e not, i n any pl ai n straight f onvar d sense, in t he one Physical Space in rvhich physical objects are supposed to be; and betrveen pairs of thenr rvhich are connected rvi th di fferent observers t her e ar e no sim ple and st r aight forward spatial or temporal relations. The objective consti tuents of percept ual sit uat ions ar e, on t his vier v, parti cul ar exi stents of a peculiar kind ; t hey ar e not physi cal , as w e have seen ; and t her e is no r eason t o sr-rpposethat they are eit her st at es of m ind or exist ent ial l v mi nd-dependent. I n having spat ial char act er ist ics, col ours, etc., they resem ble phvsical object s,as or dinar ily concei ved ; but i n their pr ivacy and t heir depenclence on the body, i f not the m ind, of t he obser ver t hey ar e more l i ke mental states. I give t he nam e of , r sensa "

r.8z MIND'S KNOWLEDGE OF EXISTENTS to the objective constituents of perceptual situations' on the supposition that they are aot literully parts of the physical object which we are said to be " perceiving ", and that they are transitory particulars of the peculiar kind which I have just been describing. And I call the theory which assumes the existence of such particulars tt Th e S ens um T h e o ry " . The Sensum Theory is at once faced rvith the question : " What is the relation between the objective constituent of a perceptual situation and the physical object which On the two we are said to perceive in this situation?" previous theories it was possible to admit that, in favourable cases, the objective constituent of the perceptual situation was quite literally a spatio-temporal part of the perceived object. This cannot be admitted on the Se ns um T heor y ; th e re l a ti o n m u s t b e l e s s di rect and mo r e c om plic at e d th a n c o mmo n -s e n s e b e l i eves. On the Sensum Theory the proposition : " l'he physical object which I am norv perceiving appears to have the determinate characteristic r" can be analysed uP to a The analysis would run as follorvs. certain point. Th i s pr opos it ion me a n s : " T h e re i s a c e rt ai n sensum. s which is the objective constituent of this perceptual si tuat ion. T his a c tu a l l y h a s th e c h a ra c te ri sti c c w hi ch I can det ec t in i t b y i n s p e c ti o n , a n d i t h a s thi s characteristic in a straightforward dyadic way. And there is a certain physical object o, to which this sensum has a ce r t ain r elat ion R w h i c h i t h a s to n o o ther physi cal o b j ec t . I n v ir t ue o f th i s re l a ti o n th e s e n s u m s i s sai d to be "an appearance of " the physical object o. When we say that several people perceive the same physical object a and the same part of it, rve must mean, on this theory, that their several perceptual situations contain a s objec t iv e c ons ti tu e n ts th e s e n s a J ,r J 2 1. . . etc., and that all of them are appearances of the same physical o b j ec t o. I t is p l a i n th a t th e s e a n a l y s e s contai n an unanalysed factor, viz., the relation R of " being an appearance of ". About this relation we can say the

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following things. (i) It is not the relation of spatiotcmporal part to spatio-temporal whole. (ii) It is a many-one relation, i.e., many different sensa can be appearances of one physical object, and even of precisely the same part of this object ; but one sensum cannot, in this sense, be an appearance of several physical objects. There is a cerrain physical object and a certain part of it which can be called .. tlae part <>f the physical object rvhich has this sensum as an allpearance ". At this point the Sensum Theory can take one of two courses. It may profoundly modify tlre common-sense notion of physical objects ; e.g., it may hold with Berkeley that what are manifested by sensa are vol i ti ons i n G od's m ind ; or r vit h Leibniz t hat what are manifested by sensa are collections of minds; rlr with Russell that the sensa which are objective t:onstituents of perceptual situations are a small selection out of certain larger groups of interrelated sensa, and that these groups are the only physical objects that tltere are. Or, on the other hand, it may try to keep fls near to the common-sense notion of physical objects as possible. The latter course leads to what I call the " Critical Scientific Theory ", which is the tacit assumption of natural scientists, purged of its inconsistencies, attd stated in terms of the Sensum Theory. According to which of these alternative views of the nature of physical objects rve choose we shall take a different vi crv of the rel ati on R bet ween a sensum and t he lrhysical object of rvhich it is an appearance. 8.g., on srrch a theory as Russell's the relation R is that of r:lass-membership. To say that s is an appearance of a will mean that o is a certain group of suitably interrcl ated sensa, and tha t s is one of t his gr oup. O n such i r thcory as B erkel ey' s t he r elat ion R is t hat of one par t of a total effect to the cause of this total effect. The total r,llirct is all the sensa rvhich rvould be said to be appear, ;rnt:esof a certai n thi ng at a cer t ain t im e. The cause i s :r certai n vol i ti on i n G od's m ind.

r84 MIND'S KNOWLEDGE OF EXISTENTS Conutton-sense and thc Tlryee Types of Theorl'. We have seen in what respects the lirst trvo theories agree rvit h t he pr im it i v e b e l i e fs o f c o mmo n -s e n se' and i n rvhat respects they differ from these. Let us now raise the It agrees sa m e ques t ion a b o u t th e S e n s u m T h e o r y' rvit h c om m on- s e n s e i n th e b e l i e f th a t the obj ecti ve cons t it uent s of p e rc e p tu a l s i tu a ti o n s re a ll y do have, i n a straightforrvard dyadic rvay, all those characteristics whic h t hey s e e m o rl c a re fu l i n s p e c ti o n to have. B ut i t has t o as s u me th a t th e s e o b j e c ti v e c onsti tuents are p ar t ic ular ex iste n ts o f a p e c u l i a r k i n d , bei ng nei ther m ent al nor phy s i c a l . A n d , a l th o u g h i t i s possi bl e for i t t o hold t hat th e re ma y b e p h y s i c a l o bj ects i n the o r dinar y s ens e o f th e w o rd , i t c a n n o t admi t that the o bjec t iv e c ons ti tu e n ts o f m o s t p e rc e p tu a l si tuati ons are i n f ac t s pat io- t e mp o ra l p a rts o f th e m . It i s thus faced rvith a problem which cioes not arise for the other theor ies 1 v iz . , to g i v e s o me a c c o u n t o f the rel ati on b et r v een s ens a , rv h i c h a re o b j e c ti v e c o nsti tuents of perceptual situations, and the physical objects rvhich are supposed to be manifested by these sensa. In order to giv e a plaus i b l e a c c o u n t o f th i s re l a ti on the theory may be forced to depart very far indeed from the common-sense notion of a physical object, as has h a ppened in R u s s e l l ' s th e o ry . I t hink t hat i t i s n o rv a b u n d a n tl y e v i d ent that very l i t t le c an be d o n e fo r c o mtn o n -s e n s e . One theory re quir es a k ind o f i n h e re n c e rv h i c h s h ocks i t ; the sec ond t heor y a s k s i t to b e l i e v e th a t the obj ecti ve constituents of rnost, and perhaps of all, perceptual si tuat ions s eem o n c a re fu l i n s p e c ti o n to h a ve cl taracteri st ic s ot her t ha n a n d i n c o m p a ti b l e rv i th those rvhi ch th ey ac t ually do h a v e ; a n d th e th i rd th e o ry i nsi sts that th e objec t iv e c o n s ti tu e n ts o f p e rc e p tu a l si tuati ons are seldom if ever spatio-temporal parts of the physical o bjec t s r v hic h it c l a i ms to b e p e rc e i v i n g , and presents i t wit h a pec u l i a r k i n d o f e x i s te n t w h i ch i s nei ther p h y s ic al nor m e n ta l b u t s e e m s to h a v e o n e l eg i n each

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realm. And these results are not due to the wilful perversity of philosophers debauched with learning. 'l'hey are conclusions to which we are forced most unrvillingly by a careful consideration of those facts rvhich common-sense i gno r es. I t hink we m ay say wit h perfect confi dence that , whilst none of t he philosophic theori es may be true, t he pr im it ive belief which accom lranies all perceptual situations is certainly to a very large extent false ; and that there is not the faintest chance of rehabi l i tat ing it . I f we r ef lect on t he hist or y and the probabl e pr ehist or y of hum an per cept ion, I thi nk w e can see that t her e is not hing in t he least surpri si ng i n thi s f act . Per cept ion m ust have gr own rrp i n cl ose connexion r vit h act ion ; and t he pr im it ive bcl i ef w hi ch forms par t of t he per cept ual sit uat ion is, on the rvhole, perfectly satisfactory for practical purposes. It i s exactl y the be lief t hat a being r vould nat ur aily l r:ach i f he i gnored abnor m al cases like m ir r or - im ages ; rreglected minor differences, such as we find on careful i rrspecti on, betrveen t he object ive const it uent s of t he pr.rceptual situations of dift'erent observers who are said to be percei vi ng th e sam e object by t he sam e or by rl i fl i :rent senses; an d knew not hing about t he velocit y of l i ght or the part played in per cept ion by his or vn l rrai n and nervous syst em . Now, a being devot ed t o pr' ;rr:ti calends natur ally would ignor e com par at ively ri ul : cases, such as m ir r or - im ages and ot her opt ical i l l rrsi ons. H e nat ur ally would neglect t he m inor rl i l l i ,rerrces betw een t he char act er ist ics of var ious obj ccti vt: consti tuents, so long as t hey all guided him t o tl rt, ri ght pl ace and enabled him t o co- oper at e sat isl ;rctori l y rvi th hi s fe llor vs, t o avoid danger , and t o get rvl r;rthe l vanted. From t he nat r r r e of t he case he could n()t srrspcctthe vel ocit y of light , which needs t he m ost rl cl i catr:experi ments t o det ect it and a st r oke of genius .vr,n to thi nk of i t. And, as he ahvay'scar r ies his br ain ,rrrrlncrvous system about r vit h him wher ever he goes, l rr. rvotrl d natural l y t end t o ignor e t he par t which it

186 MIND'S KNOWLEDGE OF EXISTENTS plays in perception ; just as a person rvho ahvays wears glasses forgets that he has them on and that he could not see properly without them. These causes, which must certainly have operated in the development of p e r c ept ion, hav e p ro d u c e d p re c i s e l y th e k i n d of pri mi ti ve belief which rve might have expected them to produce. And, when we take into account all the factors which were ignored in the development of this belief, but which are none the less real, we naturally find that the belief i s f ar t oo s im p l e -m i n d e d to d e a l w i th t he extremel y com plex s it uat io n . It i s , th e re fo re , i n m y o pi ni on, si mpl y waste of time to try to rehabilitate naive realism ; or to regard it as any serious objection to a theory of the external world and our perception of it that it is {tshoc k ing t o c o m m o n -s e n s e " . A n y th eory that can possibly fit tbe facts is certain to shock common-sense somewhere ; and in face of the facts we can only advise com m on- s ens e to fo l l o w th e e x a mp l e o f J udas Iscari ot, a nd " go out an d h a n g i ts e l f" . W e m ay now a s k o u rs e l v e s w h e th e r th e re i s anythi ng to c hoos e bet r v e e n th e th re e k i n d s o f th eory. (r) It seem s t o m e t ha t th e T h e o ry o f IVl u l ti p l e Inherence, as stated, presupposes a doctrine of Absolute Space-Time, a s a k ind of f u n d a m e n ta l s tu ff o r m a tri x . It i s qui te certain that the objective constituents of perceptual si t uat ions ar e pa rti c u l a r e x i s te n ts , a n d n o t mere uni versal q ualit ies . A nd i t i s q u i te c e rta i n th a t, i f obj ecti ve consti t uent s of v is u a l s i tu a ti o n s a re re a l l y s i tuated w here they appear to be, as the theory assumes, they are often situated in places rvhich are not occupied by matter in any ordinary sense of the rvord. This is often true, e..g.,of. mirror-images. Now, a mirror-image is as good a particular as the objective constituent of a more normal vi s ual s it uat ion. W h e n c e d o e s i t g e t i ts parti cul ari ty ? On t he pr es ent th e o ry w e m u s t s a y th a t i t is a parti cul ar because it is a certain region of Space, pervaded from a certain other region of Space at a certain date and for a certain time by a certain shade of colour. Norv

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this surely presupposes Space-Time as a kind of omnipresent and eternal subst ance, ever y r egion of which is ready to be pervaded by some sensible quality from some other region. I do not of course suggest that this theory must suppose t hat Absolut e Space- Tim e is t he ortly substance in the material realm. The regions from which colours pervade other regions are occupied in a non-triadic sense by certain physical and physiological events and objects. And the emitting regions are also occupi ed i n a non - t r iadic sense by elect r ons, at om s, molecules, etc., and their movements. It is not necessary for the theory to hold, e.g., that an electron is just a certain region of Space-Time dyadically pervaded by some physi cal qual it y. But , whilst it is not necessar y for the theory to hold that Absolute Space-Time is the ouly substance in the material realm, it zs necessary for i t to hol d that A bsolut e Space- Tim e is a subst ance and that the parti cul arit y of t he object ive const it uent s of some, i f not al l , percept ual sit uat ions is t he par t icular it y of some particular region of Space-Time. This region is marked out by being pervaded by such and such a sensi bl e qual i ty from such and such a r egion of pr o.i ccti on ; and a reg ion t hus per vaded and m ar ked out is, on the present theory, that kind of particular rvhich rve call " an objective constituent of a perceptual si ttrati on " . Norv, I do not for a moment suggest that a theory is rrccessari l y w rong b ecause it pr esupposes t he doct r ine of A bsol ute S pace- Tim e as t he com m on m at r ix of all ob.iective constituents of perceptual situations. But I rkr think that such a theory starts with rather heavy l i abi l i ti es, and I do suspect t hat it has not car r ieci it s l unal ysi s far enough. (z) It seems to m e t hat t he Theor y of a M ult ipt e l { r' l :rti on of A ppearing is liable t o a sim ilar object ion. S rrppose I hol d up a f inger in f r ont of a plain m ir r or , so that I can see bo t h t he f inger and t he m ir r or - im age of i t at the same ti m e. Then it is quit e cer t ain t hat t he

I88 MIND'S KNOWLEDGE OF EXISTENTS characteristic colour of my finger su/tts to pervade the surflacesof two distinct physical objects, one in front of the mirror and the other at the back of it. It is also quite certain that the characteristic sensible form of my finger seenu to inform two distinct physical objects' Now we have every reason to believe that only one p h y s ic al objec t i s a p p e a ri n g i n th i s s i tu ati on. It i s therefore not enough for the theory to hold that some part of a physical object which is an objective consti tuent of a v is u a l s i tu a ti o n ma y s e e m to have a characteristic which it does not in fact have. It must also assert that what is in fact one physical object in one place may seem to be two physical objects in trvo Now one may admit places at some distance apart. might seem to have a that a certain particular characteristic which differs from and is incompatible with the characteristics rvhich it does have. But I find i t alm os t inc r edi b l e th a t o n e p a rti c u l a r e x t ended patch should seem to be trvo particular extended patches at a distance apart from each other. There is of course no d i ffic ult y in hold i n g th a t th e s a m e s h a d e o f col our and the same sensible form may appear to inhere in trvo places at once, and that one of these places is physically filled rvhilst the other is physically empty ; provided yo u hold t hat c olo u rs a n d s e n s i b l e fo rm s s e e m to i nhere, not in physicat olyetls, but in regions of Space. The appearance of two particulars is then accounted for by the fact that there really are two particulars, viz., the tw o dis t inc t r egio n s o f Sp a c e i n w h i c h th e same col our a n d s ens ible f or m s e e m to i n h e re a t th e same ti me. Bu t t his pr es up p o s e s A b s o l u te S p a c e -T i m e as a substantial matrix rvhose regions are ready to appear to have such and such characteristics from other regions w h i c h ar e s uit ab l y fi l l e d . A n d th i s rv a s the obj ecti on to the T heor y of M u l ti p l e In h e re n c e . I t hink we m u s t s a y th e n th a t, i n v i e rv of mi rror' i mages , aber r at io n , e tc ., th e Mu l ti p l e R e l ati on Theory of Appearing must hold either that what is in fact a

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single extended particular can seem to be two distinct extended particulars at a distance apart from eaclr other; or that sensible qualities and forms have the relation of " appearing to inhere in " to regions of Absolute Space - Time, and not to the surfaces of physical objects. The first alternative is difficult to believe; the second presupposes Absolute Space-Time, which is probably a sign of inadequate analysis. (S) It is commonly objected to the Sensum Theory that it leaves the existence of physical objects merely hypotheti cal ; that i t int r oduces ent it ies of a peculiar kind, whose status in the world and relations to physical objects, if such there be, are very difficult to understand ; and that i t i nvolves aver y odd kind of causat ion, w hi ch i s al most creat ion out of not hing. I n t his sect ion I shal l content myself wit h showing t hat t he Sensum 'l'heory is in these respects very little worse off than the other tw o al ternati ves. I t is no doubt t r ue t hat sensa r:annot be parts, in the literal and straightfonvard sense, of physical objects ; and that, on most forms of the theory, the relation between the trvo is very indirect. A s agai nst thi s i t m ust be said t hat t he ot her t heor ies havc been found to involve Absolute Space-Time. Now I thi nk that the S ens um Theor y can dispense wit h t his. 'l'hc other theories need this because they require some l < i nd of substance for sensible qualit ies t o inher e in or l () seem to i nhere i n. And, since in t he case of m ir r or i nrages, etc., thi s subst ance can har dly be t he sur f aces of physical objects, there seeins norhing left for it to be r.xt' t:pt vari ous regi on s of Absolut e Space- Tim e. Now tlrr: Sensum 'fheory starts rvith particulars, for each sr.nsum i s a parti cul a r having t hose sensible qualit ies l rrrrl that sensi bl e for m which it seem s on car ef ul irrspt:ction to have. It therefore does not need to ,;rssurneA bsol ute S pa ce- Tim e, in t he sense of a kind of srrl rstanti al matri x w hose var ious r egions st and r eady to l rr: pervadcd by var ious sensible qualit ies and inl ,rrrrrcd by vari ous sensible f or m s. I t can accept a

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relational theory of Physical Space-Time; and this certainly seems to me to be a point in its favour. It can start with the sensibte spatio-temporal relations of sensa in the same sense-field or the same sense-history, and lhus e*mplify the general notion of a Space or a SpaceTi me of int er r elat e d p a rti c u l a rs . T h e n , b y consi deri ng the correlations between sensa in different sense-fields and different sense'histories, and by taking account of the connexion of these with the movements of the observer's body, it can construct in thought the concept T h i s P hysi cal o f. a s ingle P hy s i c a l S p a c e -T i m e . plt'Tsical eaents of all Space-Time will be the system sensa in a rvay as are interreiated in the same hind of tw o ki nds of si n gle s ens e- his t o ry . T h e re l a ti o n s i n th e whole differ in detail, but there is enough analogy between them to justify us in regarding the rvorld of physical events as a single spatio - ternporal system h a ving a c er t ain k i n d o f " g e o -c h ro n o me try " . Thi s i s the justification of the notion of Absolute Space-Time; but it is no justification for treating it as a substantial matrix, as the other theories have to do. I have dealt with the details of this synthesis to the best of my ability in my Scientific Thoaght, and I must refer the reader to the Second Part of that book for such justification as I can give for the above dogmatic statements. Let us now consider the objection that the Sensum Theory makes physical objects entirely hypothetical' mere Dinge-an-Sic/t. I shall deal directly with this question in the next section. Here I shall merely consider whether the ottrer theories are much less liable to the same objection. I cannot see that they are. I profess to have proved earlier in this chapter (a) that, even if there had been no delusive perceptual situations, it is certain from the nature of the case that n o per c ept ual s i tu a ti o n c o u l d c o n ta i n l i teral l y as i ts objective constituent the physical object which we are sa i d t o be per c e i v i n g i n th a t s i tu a ti o n . 1 /) That the existence of totally delusive situations shows that the

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objective constituent cannot alzuays be even a spatiotemporal part of the physical object which we are said to be perceiving. Hence even this modified claim can neuer be accepted at its face-value, since it is made as strongly in the perceptual situations which are certainly delusive as in those which are not knorvn to be so. (r) That, in view of the discrepancies which careful inspection discovers between the objective constituents of perceptual situations when one observer is said to be seeing and touching the same object or when several observers are said to be seeing the same object, even this modified claim cannot be true except on the very speci al assumpti ons of t he Theor y of M ult iple I nher ence or the Theory of a Multiple Relation of Appearing. On any vi ew , then, t he claim s of t he individual per ceptual situation to reveal a certain physical object and to guarantee its existence must be attenuated to a mere shadow . A nd, when we com e t o consider in det ail the two theories which are able to admit this attenuated claim at all, we find that the claim must be pared down sti l l more; as I w i l l now shor v. If the Theory of Mult iple I nher ence be t r ue, all t hat I can learn from a single perceptual situation is that a certain external region of Space, which may or may not now contain relevant physical events and objects, is at present pervaded by a certain sensible quality and informed by a certain sensible form from the place where my body now' is. If I want to get any further than this ; to know whether I am perceiving a ,. real olrject " or only an image I to know what spatial and other qualities I may ascribe to it in itself and apart from its relation to my organism ; I must do this, if :rt all, by considering the objective constituents of a number of different perceptual situations belonging to nryself and to others, and noting the relations between them. A nd the physical object r vhich I t hen , , know ", :rnd to rvhich I ascribe these intrinsic characteristics, is logically (though not psychologically) just a hypo-

rg2

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thetical entity postulated to explain and systematise these correlations. The position is precisely similar if we adopt the Theory of a Multiple Relation of Appearing. All that I can learn from a single perceptual situation is that a certain surface, which seetns to be a spatio-temporal part of a physical object, seetts to have such and such a shape, position and sensible qualit y . If I w a n t to k n o w w h e ther i t es part of a phy s ic al o b j e c t; o r w h a t k i n d o f physi cal obj ect thi s is ; or r v h a t s h a p e , p o s i ti o n a n d i ntri nsi c qual i ti es i t ac t ually h a s; I mu s t d o th i s , i f a t al l , by the same method of comparison and correlation as on the M ult iple I n h e re n c e T h e o ry . T h e p hysi cal obj ect w hi ch I am said to " perceive ", and the properties which I ascribe to it, are again logically (though not psychologically) in the position of hypothetically postulated ent it ies . I t is of c o rrrs e o p e n to th e s u p p o r ter of the Mul ti pl e Inherence Theory to assert that there may be one specially favourable position (a.g., rvhen one is " looking straight down on a penny from the distance of most distinct vision ") in rvhich the geometrical shape and t he i n tri n s i c c o l o u r o f th e penny are di rectl y revealed, instead of the colour which it has from a place and the sensible form which inheres in it from a plac e. An d i t i s o p e n to th e s u p p orter of the Theory of a M ult ip l e R e l a ti o n o f Ap p e a ri n g to assert that there may be one specially favourable position in rvhich the qualities which a physical object lras, and not merely those which it seens to have, are revealed directly to the percipient. On such assertions I have the following c om m e n ts to m a k e . (i ) T h e y a re i n the hi ghest W e a re a s k e d t o bel i eve that i n degr ee un l i k e l y . one special position the physical, physiological, and psychical mechanism produces an utterly different result from that which it produces in all other positions, no matter how close to this specially favoured one. (ii) 'fhere is nothing in the nature of any perceptual situa-

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tion, takerr by itself, to reveal to us that it differs in this remarkable rvay from all the rest. The unique perceptual sit uat ion, if such t her e be, does not com e vi si bl y " trailing clouds of glor y behind it ". I t r vould have to be discovered to have this property by compari ng i t and it s object ive const it uent r vit h ot her per ceptual si tuations and t heir s. ( iii) I t is just as possible, logically, for the Sensum Theory to make this preposterous cl aim as f or t he ot her t wo t heor ies, I t m ight assert that, from one specially favourable position, the obj ecti ve const it uent is lit er ally a par t of t he physical obj ect, and that t he qualit ies which we det ect in it ar e l i teral l y those of t he physical object ; whilst , in all ot her si tuati ons, the object ive const it uent is a m er e sensum . I thi nk I ma y f air ly conclude t hat t he object ion t hat on the Sensum Theory the perceived physical object becomes a mere Ding-an-Sic/t applies rvith almost equal force, i f i t app lies'at all, t o t he ot her t heor ies. Let us norv consider the objection that the Sensum 'fheory involves a very odd kind of causation, which i s al most creat ion of par t icular s out of not hing. I r vill first shorv that the other theories also involve very odd ki nds of causat ion. The Theor y of M ult iple I nher ence i nvol ves i nstant aneous act ion at a dist ance. When a ccrtain process goes on in my brain and nervous system a certain remote region of Space becomes pervaded by rr certain colour from rvhere I am. So far as we knorv thi s i s an i nstant aneous pr ocess. The dat e of per vasion i s i denti cal w it h t he dat e of t he event s in m y br ain and ncrvous system, though the pervaded place may be rrri l l i ons of miles f r om t he r egion of pr oject ion. And nothi ng that m ay be physically occupying t he int er vcni ng space is r elevant t o t his pr ocess of per vasion; so that w e cannot conlpar e t his act ion at a dist ance rvi th pushi ng a dist ant body and m aking it m ove inst;rntaneousl y by m eans of a r igid r od. Ther e is in lrr<:t,.so far as I knorv, no analogy elservhere to the kind ol r:ausati on which t he Theor y of M ult iple I nher ence

rg4 MIND'S KNOWLEDGE OF EXISTENTS has to postulate. I do not make this an objection to the theory ; but I do sa1' that it is in no position to cast stones at the Sensum Theory for having to postulate an odd kind of causation. Exactly the same remarks apply, nnrtatis tnutandis, to the Theory of a Multiple Here processes in the brain Relation of Appearing. a n d ner v ous s y s te m i n s ta n ta n e o u s l y cause certai n qualities to seem to inhere in places rvhere they do not in fact inhere ; or else they make one distant particular seem to be two distant particulars. I rvill norv consider more directly the special objection to t he S ens um T h e o ry o n th e g ro u n d s o f the pecul i ar kind of c aus ati o n rv h i c h i t i n v o l v e s . T he obj ecti on i s th at , if t he S en s u m T h e o ry b e tru e , p h y s i cal and physi ological processesct'eotecertain particular existents, viz., sensa, rvhich do not form parts of the history of any physical object. Now it is said that we can understand that a process in one substance may cause a certain quality to characterise the next phase in the history of an alr eady e x i s ti n g s u b s ta n c e ; b u t w e cannot understand the kind of creation of particulars which the Sensum Theory requires. To this I ansrver (i) that there are certain forms of the Sensum Theory which d o not inv olv e th i s c re a ti v e k i n d o f c a u sati on but onl y a s elec t iv e k ind . Ac c o rd i n g to s o me th eori es physi cal objects consist of groups of sensa, and a physical object i s per c eiv ed wh e n a c e rta i n s e n s u m o f a certai n group becomes the objective constituent of a perceptual situati on. O n t hi s ty p e o f th e o ry th e functi on of the physical, physiological, and psychical mechanisrn of perception is not to create sensa, but merely to select from a group of pre-existing sensa a certain one and to make it the objective constituent of a certain percept ual s it uat i o n . I c a n n o t, h o rv e v e r, l ay much stress o n t his ans we r, b e c a u s e I d o n o t th i n k that a purel y s elec t iv e f or m o f th e S e n s u m T h e o ry i s pl ausi bl e i n vierv of all the facts. I have explained my reasons for this in my Scientifc Tltought, and will not repeat

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them here. (i i ) The m or e dir ect answer t o t he pr esent obi ecti on i s the fol lor ving. A sensum is not som et hing that exists in isolation ; it is a differentiatecl part of a bigger and more enduring whole, viz., of a sense-11eld rvhich is itself a mere cross-section of a sense-hzlstoty, Suppose, e.g., that I am aware of a red flash. This is a di fferenti ati on of m y t ot al visual f ield at t he m om ent ; and my total vi sua l f ield at t he m om ent joins up r vit h and conti nues my e ar lier visual f ields, f or m ing t oget her w i th them my vi sual sense- hist or y. The sense- hist or y i s a conti nuant ; a kind of subst ance, t hough not a thy.ricol substance. And the new sensum is not an i st> l ated parti cul ar, but an occur r ent in t his peculiar ki nd of conti nuant. Thus t he causat ion involved in t he Sensum Theory, though very different from physical < :ausati on, i s not the sudden cr eat ion of a per f ect ly i sol ated and l oose par t icular out of not hing. I t is, t o s;ry the l east of i t, no odder t han t he causat ion involved in the other trvo theories. ' l ' he upshot of this discussion seem s t o m e t o be t hat , on the whole, there are no greater objections to the S r.nsum Theory than t o t he ot her t heor ies, and t hat l he other theori es have no posit ive advant ages over thr: S ensum Theory r vhen car elully consider ed. And, ;rs the S ensum Theor y does not r equir e t o assum e A bsol ute S pace-Ti me as a pr e- exist ing m at r ix, r vhilst tl rt: other theori es ap par ent ly do, t he balance of advant ;rg' c seems to be slight ly on t he side of t he Sensum ' l ' l rcrl ry. It remai ns nolv t o ask: . , Hor v m uch of t he (' ()nl rnon-sensenoti o n of a physical object can we keep; :rnrl rvi th w hat degree of conf idence can r ve believe t ir at tl tcrr: are thi ngs rvhich answer t o t he var ious par t s of l l rr. < :< l mrnon-sense not ion of a physical object ? " ln u,/tttl Sense can -.t,eacce?t Ph.Tsical Objecls 2 If rve r orrsi < k' r the common- sense not ion of a physical object w r.(' rn di vi de i t i nto f our logically independent par t s. (i ) l t i s strl tposed to be m or e per m anent t han t he per r r.Jrtrr:rlsi tuati on. The lat t er is held t o be t r ansit or y

196 MIND'S KNOWLEDGE OF- EXISTENTS as compared with the former. (ii) It is supposed to be public to a number of observers, and to be capable of exhibiting different aspects of itself to different senses of the same observer. (iii) It is supposed to be literally extended in Space, having a bounding surface of a certain geometrical size and shape, and standing in straightfonvard spatial relations to other physical objects. (iv) The objective constituents of the tactual and visual situations in which it is said to be perceived are held to be literally parts of its surface. We have seen reason to reject (iv). The first two are accepted by nearly every one. The average scientist who thinks about the matter accepts the first three and is in an inextricable muddle about the fourth. Berkeley, Leibniz, and Russell accept the first two and reject the rest. It is therefore reasonable to think that there is better evidence for (i) and (ii) than for (iii) and (iv) ; or at any rate that there is less to be said against the first pair than against the last pair. The evidence for (i) is of the following kind. For long periods of time rvhenever I look in a certain direction I am aware of very much the same kind of objective constituentt €.{.; a visual appearance of my table. Now merely looking in this direction from this place is not a sulficieral condition for this kind of objective constituent to appear. For sometimes (a.g., when my room is being spring-cleaned) I may look in this On the other direction with quite different results. hand, looking in this direction from this place is a necessarycondition, over long periods of time, for this objective constituent to appear to me. Now the point to notice is that I can fulfil this condition at quite I do so during a arbitrary intervals, and that zuhenez,er long stretch of time I am arvare of the same kind of The natural interpretation of objective constituent. such facts is that there is another and relatively perrn anent nec es s a ryc o n d i ti c l n o n rv h i c h a l l th ese arbi trari l y initiated perceptual situations depend, and that this

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determi nes the l i ken ess bet ween t heir object ive con_ stituents. This conclusion is supported by three other sets of facts. (a) When I am not in my room other people may be. A nd they tel l me tha t t hey have had visual exper iences very much l i ke those u, hich I have when I am in t he room and l ooki ng i n t he r ight dir ect ion. This suppor t s the vi erv that there a r elat ively per m anent necessar y .is condi ti on, w hi ch i s i ndependent of m y pr esence. (t) | have conti nu ally cer t ain kinds of exper iences rvhich I ascribe to my own body. Now other people tell me that my body appears to them in exactly ihe same w ay as any othe r physical object . And I have no reason to doubt this, because I know that their bodies appear to me in exactly the sarne way as other physical obj ects. I knorv from int er nal sensat ion t hat m v- bodv conti nues to exi st w he n ot her people ar e t r ot , ""lng o, touchi ng i t; and I a m t old by ot her people t hat f iey have the same ki nd of e. 'idence f or t he cont inued exisi_ ence of their bodies when ./ am not seeing or touching them. I have not this kind of dir ect evidence about chairs and tables ; but the analogies in other respects betrveen them and human bodies make it reasonable for me to treat them in the same way. That is, they support the view that something which is capabh if producing a perceptual situation rvith a characterisric ki nd of obj ecti ve const it uent per sist s, even when no .such situation is aclually being produced, because the other necessarycondi t ions ar e not being f ulf illed. (r) If I l ook for some t im e in a cer t ain dir ect ion, a. g. , at my fire ", as rve say, I often find a slow and steadv " r:hange in the objective constituents of the successirrl vi sual si tuati ons. If I go out of t he r oom , and, on nl ttrrni ng after some t im e, look again in t he sam e rlirection from the same place, I shill again be arvare of an obj ecti ve consti tuent which in t he m ain r esem bles tl rose of w hi ch I w as a war e bef or e. But t her e r vill be llrt:rin differences; and in general the differences are

r98 MIND'S KNOWLEDGE OF EXISTENTS by a steady consuch as would have been produced I observed which tinuation of that process oi change that I can Nothing rvhile I r.as formerly in the room' accounts for the Jet"ct in myself during the interval before difference between the Tast objective constituent I after I rvent out and the first objective constituent that is So the naiural interpretation came in. ;g;; depended in tfi" o.igin"l series of objective constituents this process part on a process outside my body, and that absence' my i,t, gon" on further during arguments I ?o not say that any or all of these that the view the of amount to a knock-do*n proof are' in situations objective constituents of perceptual outsi de c as es ' par t ly d e p e n d e n t o n s o m e th i ng ;;ty themth an p e rm a n e n t bo d y th e i er c ipient -But ; s " n dthat, -o t"if it be granted that this think I do seluer. such facts hypothesis has any finite initial probability' p r obabi l i ty' ri i t.g. , - ent s do g i v e i t a v e ry h i g h fi n a l this accepted have philosophers ai And iractically v i e w ' mu ch of t he c om m o n -s e n s e vrew l s (i i ) T he s ec ond p a rt o f th e c o m m o n -s e n se but not necessary' and that these relatively permanent neutral are situations sufficient, conditions of perceptual means merely this If as betrveen differertt percipients' condi ti ons t" t o f p e rm a n e n t th a t one and t he ,.." from vary with other conditions rvhich .ty .o-op"rate perceptual obserue, to observer, and may produce this is situations with correlated objective constituents, o f c o ntemporary a l so highly lik ely . T h e re a re g ro u p s constituents are objective whose percepirral' situaiions all said to refer to are they that so .elat"d to each other the case of a take we If the same external object' the top seeing be to number of observers who are said correlations' follorving of the same penny, rve find the that' All the observers are looking in such directions each into run if they moved along them, they 11911d thei r of o f e ach o th e r at t he s am e p l a c e ' In th e mi d d l e these All visual fields there is an outstanding patch'

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p;rlclres appear to have some shade of brown ; they illlpcar to be of different sizes and to have different rr.rrsi l rl cdepths i n thei r r espect ive f ields. They appear lo lurvr. various shapes, but all these shapes are proi tl ti on-s of a ci rcl e. A ll t he obser ver s will be able t o l r.r' ,' 1. aw are of correl at ed t act ual object ive const it uent s, i l tl rr.y rval k up to the place at r vhich t heir lines of sight i trl r:rsr:ct. A nd, as they r valk in t hese dir ect ions, each rvi l l prassthrough a series of visual sit uat ions; t he t ot al l l rj r.r:ti vcconsti tuent of each sit uat ion r vill be a colour ed l i rl rl rvi th a brow n patch in t he m iddle of it ; t he shapes ol tl rcst: patches w i l l al l be pr oject ions of a cir cle; and l l tr,srrr:r:cssi ve patches of each ser ies will be of dim inishi rrg sr.rrsi bl edepth i n th eir r espect ive visual f ields, and ol i rrcrr:;rsi ngsensi bl e si z e and clear ness. It i s l rard to resi st the convict ion t hat such gr oups of r' ul rr.l ;rtr:dperceptual si tuat ions depend on t wo f act or s. ()rrt. rs a rel ati vel y perm anent condit ion, independent ul tl rr, observers and t heir bodies. The ot her is a r nrrl i ti on w hi ch vari es f r om obser ver t o obser ver and fl l fl rr.frr.sas thc posi ti on and or ient at ion of t he per r' l pi t.rrt' .sbody. Moreove r , t he f act or in t hese per cept ual rl l rrnl i orrs w hi ch seems to be specially closely cor r elat ed w i tl r l l ri s r:ol nmon i ndependent condit ion is t he out rtarrrl i rrg patch w hi ch i s at t he m iddle of each visual l i r' l rl , S rrppose that al l t he obser ver s st and and f ace as Irr.l orr.,al rd that ., the p enny is r eplaced by a t ennisIral l " , i rs w e say. Then t her e r vill be a sim ult aneous r l rrrrgr. i n thc outstandi ng cent r al object ive const it uent rrf rrl l tl rr.sr:vi sual si tuati ons. Thus it seem s r easonable In ru r r.pl tl rc second par t of t he com m on- sense view. l l t' { rr.;rsonl rbl eto hol d t hat t he object ive const it uent in st Irl tr r.ptrral si tuati on i s in m any cases det er m ined by Irrrrrr,t., ol r:ondi ti ons. One is specially bound up wit i. l tl r! l r.rr i pi r:nt :rnd hi s b ody; t he ot her is independent rf 1rr.rr rpi r.rrtsi rrrd thei r bodies. Eit her can var y r vit hout Il l ' otl rcr. V ari ;rti ons o f t he lat t er involve cor r elat ed r.stt{ rtrrns i rr ;r t:crtai n par t of t he obiect ive const it uent s

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of a whole group of perceptual situations belonging to different observers. Variations in the former affect only the objective constituents of the perceptual situations of a single observer. When many people are said to a group of per" perceive the same object " we have jointly by a coilt"to't ceptual situations determined independent c o n d i ti o n a n d b y o th e r c ondi ti ons w hi ch vary from one observer to another. If this hypothesis starts with a finite initial probability, the facts strrely giv e it a high fi n a l p ro b a b i l i ty . (iii) It remains to consider horv far the facts make for or against the third part of the common-sense vierv I viz., that these relatively permanent and neutral conditions of groups of correlated perceptual situations are l it er ally ex t en d e d , h a v i n g g e o m e tri c a l s hapes and si zes, a nd hav ing s p a ti a l re l a ti o n s to o th e r th i ngs of the same kind. Up to the present all that has been established is equally compatible rvith the primitive beliefs of common-sense, rvith the theories of Descartes and the natural scientists, and with the speculations of Berkeley, of Leibniz. or of Mr Russell. For each of these parties admits that such groups of perceptual situations are joint ly depen d e n t o n a c o n d i ti o n , w h i ch i s rel ati vel y per m anent an d n e u tra l b e tw e e n th e p e r ci pi ents, and a variable condition which is specially connected rvith

of a particular perceptual situation. For Mr Russell t he neut r al a n d re l a ti v e l y p e rm a n e n t condi ti on i s a

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l )r.11rcl )tualsi ttration exist s alr eady, and t he var iable r' ,rrrrl i ti ons si mpl y select a cer t ain par t or a cer t ain rrrr,nrl rt' rfrom thi s pr e- exist ing whole and m ake it t he ol rj tr:ti vc consti tue nt of a cer t ain per cept ual sit uat ion. ' l ' l rr: C artesi an, t he Leibnit ian, and t he Ber keleian f lrr.rrrir:smay be called creatiue; for, as usually stated, l l rr.y ;rs,sumethat the object ive const it uent s do not exist out of thc percep t ual sit uat ions. They assum e t hat , rvl rr.r b' th sets of condit ions ar e f ulf illed, a sensum of rr (' (' r' t.i l l ki nd arises in a cer t ain place in a cer t ain ,.,.rrsr.-l i t:l d;but that , r vhen t he var iable condit ions

( )rrr.r' :rrrnotsay, i n any lit er al sense, t hat G od's habit s rrl vol i ti on, or a co lony of unint elligent m onads, or a l :r()up of i nterrel at ed sensa, have geom et r ical shape, al zr.,or l l osi ti on. Norv I have argued that we can never be sure that the rlr j'r't ivr: t:
i c rr.i rsorr;rl l l t,. C ert ain gener al ar gum ent s have been Ix,' rr1' l rt ;rgtri nst the r ealit y of spat ial qualit ies and rr' l i rfrrrrrs. l f these r ver e valid ao/ / t ir t g could lit er ally l trrr' r..,11;s1y,., si ze, o r posit ion. I t r vould f ollor v t hat rr,rl rrrl ' l i l i . the comm on- sense view of physical object s r rrrrl rlpossi l l l y be true. Bt r t , in t he f ir st place, all t hese !r H rrr' rrs s.r:rn to rn e t o be plai'ly f allacious. secondly,

2O2 MIND'S

KNOWLEDGE

OF EXISTENTS

if t hey be v a l i d a t a l l , th e y mu s t a PP l Y , not onl y to the s uppos ed p e rs i s te n t a n d n e u tra l c o n di ti ons of perceptual s it uat ion s , b u t a l s o to th e o b j e c ti v e consti tuents of these s it uat ions th e m s e l v e s . If th e re b e some i nternal contradic t ion in th e v e ry n o ti o n o f s p a ti a l qual i ti es and rel at ions it r v i l l b e a s i mp o s s i b l e fo r th e obj ecti ve consti tuents of perceptual situations to have these qualities or to s t and in th e s e re l a ti o n s a s fo r a n ythi ng el se to do so. Now t he o b j e c ti v e c o n s ti tu e n ts o f vi sual and tactual sitrrations certainly seeitton careful inspection to have s hapes a n d s i z e s , a n d to s ta n d i n spati al rel ati ons to ot her c o n te n ts o f th e s a me s e n s e -fi el d. Thus anyone rvho accepts these general arguments against the reality of s pat ia l q u a l i ti e s a n d re l a ti o n s must be prepared to hold t ha t w e a re mi s ta k e n , a n d e normousl y mi staken, about the ob-J'ectiueconstihtents of ou'r perceptual situations as well as about their neutral and persistent conditions. It is not merely a mistake about details, as it r v ould be i f s o m e th i n g w h i c h w a s real l y round seemed to be elliptical ; it rvould be a mistake about a fundam ent al d e te rmi n a b l e c h a ra c te ri s ti c w hi ch seems to belong t o th e o b j e c ti v e c o n s ti tu e nts of al l vi sual and As I h a v e s a i d, the arguments t ac t ual si tu a ti o n s . agains t th e re a l i ty o f s p a ti a l c h aracteri sti cs seem to m e plain l y fa l l a c i o u s ; b u t, i f I coul d see nothi ng wr ong w i th th e m , I s h o u l d s ti l l venture to thi nk i t m uc h mo re l i k e l y th a t a n a rg u m e n t i s i nval i d, though it s eem s to me s o u n d , th a n th a t the obj ecti ve cons t it uent s o f v i s u a l a n d ta c tu a l s i tu a ti ons arc unextended, t hough t h e y s e e m to h a v e s h a p e s , si zes and posi ti ons. For I knorv fr<,rmsad experience that I can be taken in by pla u s i b l e b u t fa l l a c i o u s a rg u m ents, rvhi l st I have no r eas o n to th i n k th a t th e o b j e c ti ve consti ttl ents of my t ac t ual a n d v i s u a l s i tu a ti o n s c o u l d s eem to have shapes, s iz es , an d p o s i ti o n s i f th e y rv e re real l y unextended. It s eem s t o n te th e n to b e p ra c ti c a l l y certai n that the objec t iv e c o n s ti tu e n ts o f c e rta i l l perceptual si tuati ons do have spatial characteristics. It is therefore possible

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2o3

that thei r p er sist ent and neut r al condit ions m ay also Ir:tvc these char act er ist ics. The only quest ion is w hether ther e is any posit ive gr ound f or believing that they do in f act have t hem . ' I' he onl y r vay t o answer such a quest ion is t o st udy r:areful l y an d in det ail t he nat ur e of object ive consti tuents and t heir cor r elat ions. I n t he not ion of l ' hysi cal S p ace we m ust dist inguish t wo f act or s: (,r) the gene r al concept ion of a Spat ial r vhole having corrtcnts of v ar ious shapes and sizes at var ious places in i t ; :tnd (rf) the special char act er and cont ent s which ar e l rscri bed to Physical Space. I have no doubt t hat t he gcnt' ral concept ion of a spat ial r vhole spr ings f r om our nr' (l uai ntanc e wit h visual f ields. Her e we do have an r.xtcnded w hole of sim ult aneous par t s; t hese par t s, vi z., vari ously colour ed out st anding pat ches, do visibly It;rvr: vari ous shapes and sizes, and do visibly occupy vrtri otrsptosit ionsr vit hin t he whole f ield. The visual f ield l l tr:rr i s zzspa t ial r vhole u, it h w. hich we ar e acquaint ed in ,tr.rfs(:-perception,and it is the only spatial rvhole of l rry i rnporta nce wit h r vhich we ar e acquaint ed. The l rl ry.si r:alw orld, as a spat ial r vhole, is conceived on t he rurri rkrgyof the visual f ield. Bodies ar e analogous t o orrtstandi ng colour ed pat ches. They ar e conceived t o Irrrvcshapes a nd sizes, as t hese pat ches visibly do have l l rcnr I to occupy var ious posit ions in Physical Space, rur l l l r.sr:patc hes visibly occupy var ious posit ions in t he vrsrri rlfi cl d; and t o be capable of m oving about wit hin l ' l rysi r:al S pa ce, as som e of t hese pat ches visibly do m ove nl rorrt rvi thi n t he visual f ield. ( i i vr.rr the gener al concept ion of a spat ial r vhole, l rr,rrr1,rrl tcrna t ive t heor ies about it s det ailed st r uct ur e ri l rrl r' ()ntcnts ar e possible. O ur belief s about t he del rrrl r.rl stl uotrr r e and cont ent s of Physical Space ar e Ir,r' .r.tlorr t,xper iences of sight , t ouch, and m ovem ent , rrrrrl on tl rr: ver l' com plicat ed cor r elat ions u'hich t hese rrrr. l ,rrrrrtl to have wit h each
2o4

MIND',S KNOWLEDGE

OF' EXISTENTS

vi su a l field and t he v i s i b l e mo v e m e n ts o f col oured p a tch e s wit hin it , a n d b y n re a n s o f th e c o rr el ati ons b e trve en t he f or m er a n d th e l a tte r. C o n v e rsel y, the general conception of Ph1'5isal Space, which is based o n o u r a c quaint anc e rv i th v i s u a l fi e l d s , i s fi l l e d out and sp e ci fi ed in det ail b y o trr e x p e ri e n c e s o f m o vement. The hypothesis that rvhat appears to us as external objects and rvhat appears to us as our own bodies are exte n d e d ar . r d s t and i n s p a ti a l re l a ti o n s , i n the sense exp l a i n e d abov e, ac c o u n ts fo r th e c o rre l a ti o n s betrveen o b j e cti ve c on. s t iluen ts o f p e rc e p tu a l s i tu a ti o n s and for t h e i r va r iat ions as we m o v e a b o u t. An d i t i s di ffi cul t to se e t hat any alt ern a ti v e h y p o th c s i s w h i c h d oes not lo g i ca l l y r educ e t o t h i s o n e rv i l l a c c o u n t fo r s u ch facts. Ab o u t the m inut er de ta i l s o f th e p h y s i c a l s p a ti o -t emporal o rd e r th er e is r oom fo r mu c h d i v e rs i ty o f o p i n i on and f o r mu c h f ut ur e m o d i fi c a ti o n a n d re fi n e n re n t, as the facts adduced by the Theory of Relativity show. But th i s rn u c h s eem s t o m e to b e p ra c ti c a l l y c e rtai n, vi z., t h a t th e nat ur e and r e l a ti o n s o f th e p e rs i s te n t a n d neutral co n d i ti o ns of s ens a t ttu s t b e i n te rp re te d b y a n a l o gy rvi th v i srra l s ens aand t heir re l a ti o n s i n th e v i s u a l s e n se-fi el d; and that they cannot be interpreted by analogy with th o u g h t s or v olit ions a n d th e i r re l a ti o n s rv i th i n a mi nd ( a s Be rk c ley held) , or w i th th e re l a ti o n s o f mi n d s rvi thi n a so ci e ty ( r v hic h, t o p u t i t v e ry c ru d e l y , rv a s L ei bni z' s v i e w). Th u s, r v it h s uit abl e i n te rp re ta ti o n s , I a c c e p t the fi rst th re e cl a us es < - rtfhe c o mmo n -s e n s e b e l i e f a b o u t physi cal objects. 'fhe fourth clause I have t
SITNSE-PERCEPTION

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2os

Irirvt:, arrd that these objective constituents are literally lxrrts of the surfaces of those physical objects which wc arr: said to be perceiving. If we drop the fourth llrrrrsc of the common-sense belief it still remains possible l l r;rt the neutral and persist ent condit ions of per cept ual si trr;rti ons l i teral l y have som e colour and som et em per aIrrrc. A nd the col our and t em per at ur e nziglt tbe ident ical w i tfr those of the obj ect ive const it uent of one specially l ;rvoured perceptual si tuat ion. I s t her e any posit ive r' (' ;rsonto bel i eve that t his is in f act t r ue? I do not tl ri nl < that there i s. It does not seem t o be possible lrr :rt:t:ount for the correlated variations in the shapes tut(/ .tizcsof visual sensa without assigning qtrasi-spatial r;rrnl i ti es and rel ati ons to t lie per m anent condit ions of l l rcsr: vari abl e appearances and t o t he t hings r vhich rtr;rni fcst themsel ves to us by bodily f eelings. But , so f'ar as I can see, it is neither necessary nor useful l o ascri be to these per m anent condit ions anyt hing ;ur:rlrrg
2o4 MIND'S

KNOWLEDGE

OF- EXISTENTS

vi sr . r al f ield and th e v i s i b l e m o v e me n ts of col oured p at c hes wit hin i t, a n d b y m e a n s o f th e correl ati ons betrveen the former and the latter. Cor-rversely, the g e ner al c onc ept i o n o f P h y s i c a l S p a c e , w hi ch i s based o n our ac quainta n c e rv i th v i s u a l fi e l d s , i s f i l l ed out and spec if ied in de ta i l b y o trr e x p e ri e n c e s of movement. The hy pot hes is th a t w h a t a Pp e a rs to u s as external objects and rvhat appears to us as oLlr own bodies are e x t ended and s ta n d i n s p a ti a l re l a ti o n s , i n the sense explained above, accounts for the correlations betrveen o b jec t iv e c ons t i tu e n ts o f p e rc e p tu a l s i tu a ti ons and for th e ir v ar iat ions a s w e mo v e a b o u t. A n d i t i s di fi fi cul t to s ee t hat any a l te rn a ti v e h y p o th c s i s w hi ch does not l o g ic ally r educ e to th i s o n e rv i l l a c c o u n t f or such facts' Ab out t he m inut e r d e ta i l s o f th e p h y s i c a l s pati o-temporal o rder t her e is r o o m fo r m u c h d i v e rs i ty o f opi ni on and fo r m uc h f ut ure mo d i fi c a ti o n a n d re fi n e ment, as the fa ct s adduc ed b y th e T h e o ry o f R e l a ti v i ty show . B ut th is r nt r c h s eem s to m e to b e p ra c ti c a l l y certai n, vi z., th a t t he nat ur e a n d re l a ti o n s o f th e p e rs i s te ntand neutral conditit-rnsof sensa ntust be interpreted by analogy rvith vi s t r al s ens aand th e i r re l a ti o n s i n th e v i s u al sense-fi el d; and that they cattttot be interpreted by analogy with th ought s or v ol i ti o n s a n d th e i r re l a ti o n s r vi thi n a mi nd (a s B er k eley hel d ), o r w i th th e re l a ti o n s o f mi nds rvi thi n a s oc iet y ( r v hic h , to p u t i t v e ry c ru d e l y , rvas Lei bni z' s vi e w) . T hus , r v it h s u i ta b l e i n te rp re ta ti o n s , I a ccept the fi rst th ree c laus es of th e c o mmo n -s e n s e b e l i e f a bout ph1' si cal objects. 'fhe fourth clause I have to reject, for reasons rvh ic h I hav e t ri e d to ma k e p l a i n i n th e e arl i er part of th is Chapt er It is T-he Slatus of so-callul " Secondary Qualities". physical vierv that part of the common-sense of course o b jec t s lit er ally h a v e c o l o u rs ' te mp e ra tu res' etc. Thi s is a logical consequence of the view that the objective cons t it uent s of p e rc e p tu a l s i tu a ti o n s l i te ral l y have the se ns ibt e qualit ie s rv h i c h th e y s e e m o n inspecti on to

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2o5

have, and that these objective coltstituents are literally parts of the surfaces of those physical objects which we are said to be perceiving. If we drop the fourth clause of the common-sense belief it still remains possible that the neutral and per sist ent condit ions of per cept ual situations literally have some colour and some temperature. And the colour and temperature migltt be identical with those of the objective constituent of one specially favoured perceptual situation. Is there any positive reason to bel i eve t hat t his is in f act t r ue? I do not think that there is. It does not seem to be possible to account for the correlated variations in the s/zapes trnd sizes of visual sensa rvithout assigning quasi-spatial rl tral i ti es and rel ati o ns t o t lie per m anent condit ions of tlrese variable appearances and to the things rvhich rnani fest themsel ves t o us by bodily f eelings. But , so far as I can see, it is neither necessary nor useful to ascri be to these per m anent condit ions anyt hing analogotrs to the colour and, the telt?erature which rvc find in sensa. It has been found more expedient to correlate the colours and temperatures of sensa with r:crtai n ki nds of motion of cer t ain kinds of m icr oscopic parts of thei r perm anent condit ions. I t is pr act ically r:r:rtain.that the independentl-vnecessary and sufficient r:onditions of the colour and temperature of the objective r' or.rsti tuentof a gi v en per cept ual sit uat ion ar e event s rvi thi n the observer's own body; i. a. , wit hin t hat r elati vcl y permanent object r vhich is m anif est ed t o him self l ry a mass of bodi ly f eeling, and t o ot her s t hr ough r:crtai n characteri sti c visual and t act ual sensa. But , in rron-del usi ve percept ual sit uat ions, t hese bodily event s :rrt: physi cal l y determined by cer t ain m ot ions of cer t ain ;xrrti cl es i n an emi tt ing r egion; so t hat t hese ext er nal lrlrysical events are the dcy'cndentlynecessary and coutrnon t' ondi ti ons of the colour s and t em per at ur es of t he cor r el:rtcd sensa of a rvhole group of observers rvho are said to l l e ((percei vi ng the sam e ext er nal object ". Pr ovided \v(. :tre deal i ng rvi th non- delt r sive per cept ual sit uat ions

2o4 MIND',S KNOWLEDGE

OF- EXISTENTS

v is r , r al f ield a n d th e v i s i b l e mo v e m e n ts of col oured pat c hes wit hi n i t, a n d b y n re a n s o f t he correl ati ons bet r v een t he fo rm e r a n d th e l a tte r. C onversel y, the general conception of Physical Space, which is based on our ac quai n ta rrc erv i th v i s u a l fi e l d s , i s fi l l ed out and s pec if ied in d e ta i l b y o u r e x p e ri e n c e s of movement. The hypothesis that rvhat appears to us as external objects and rvhat appears to us as our own bodies are ex t ended and s ta n d i n s p a ti a l re l a ti o n s, i n the sense explained above, accounts for tlte correlations betrveen objec t iv e c on s ti tu e n ts o f p e rc e p tu a l s i t uati ons and ftrr t heir v ar iat ion s a s rv e m o v e a b o u t. And i t i s di ffi cul t t o s ee t hat an y a l te rn a ti v e h y p o th c s i s whi ch does not logic ally r edu c e to th i s o n e rv i l l a c c o ttl . l tfor such facts. A bout t he m in u te r d e ta i l s o f th e p h y s i c a l spati o-temporal or der t her e is ro o m fo r mu c h d i v e rs i ty of opi ni on and f or m uc h f utu re m o d i fi c a ti o n a n d re fi nement, as the facts adduced by the Theory of Relativity show. But t his r nt r c h s e e m s to m e to b e p ra c ti c a l l y certai n, vi z., that the natrrre and relations of the persistent and neutral conditions of sensa tuust be interpreted by analogy rvith v is t r al s ens aa n d th e i r re l a ti o n s i n th e v i sual sense-fi el d; and that they mnnot be interpreted by analogy with t hought s or v o l i ti o n s a n d th e i r re l a ti o n s rvi thi n a mi nd ( as l3er k eley h e l d ), o r w i th th e re l a ti o n s of mi nds rvi thi n a s oc iet y ( r v h i c h , to p u t i t v e ry c ru d e l y, rvas Lei bni z' s v iew) . Thus, rvith suitable interpretations, I accept the first t hr ee c laus es o f th e c o mmo n -s e n s e b e l i e f about ph1' si cal objects. '.fhe fourth clause I have to reject, f
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2o5

have, and that these objective constituents are literally Jrarts of the surfaces of those physical objects which we are said to be perceiving. If we drop the fourth clause of the common-sense belief it still remains possible that the neutral and persistent conditions of perceptual situations literally have some colour and some temperature. And the colour and temperature mig/tt be identical with those of the objective constituent of one specially lavoured perceptual situation. Is there any positive reason to bel i eve t hat t his is in f act t r ue? I do not think that there is. It does not seem to be possible to account for the correlated variations in the s/tapes rtnd sizcs of visual sensa rvithout assigning quasi-spatial rl tral i ti es and rel a t ions t o t lie per m anent condit ions of tl rese vari abl e ap pear ances and t o t he t hings r vhich rrrani fest themselves t o us by bodily f eelings. But , so far as I can see, it is neither necessary nor useful to ascri be to th ese per m anent condit ions anyt hing ;rrralogotrs to the colour and the teutperature which rve find in sensa. It has been found more expedient to correlate the colours and temperatures of sensa with r:crtai n ki nds of m ot ion of cer t ain kinds of m icr oscopic parts of thei r perm anent condit ions. I t is pr act ically r:r:rtain,that the iudependenth necessary and sufficient r:ondi ti ons of the colour and t em per at ur e of t he object ive r' ,rrrsti tuentof a given per cept ual sit uat ion ar e event s rvi thi n the observ er 's oln body; i. a. , wit hin t hat r elati vel y permanent o bject r vhich is m anif est ed t o him self lry a mass of bodily feeling, and to others through r:crtain characteristic visual and tactual sensa. But, in rron-del usi ve perc ept ual sit uat ions, t hese bodily event s l rrc physi cal l y dete r m ined by cer t ain m ot ions of cer t ain l xrrti cl es i n an em it t ing r egion ; so t hat t hese ext er nal lrlrysical events are the depcndentl1necessary and coluuon < :ondi ti ons nf the colour s and t em per at ur es of t he cor r el:rtcd sensa of a rvhole group of observers rvho are said to l l c ' t percei vi ng t he sam e ext er nal object , , . Pr ovided \r,(.are dealing rvith non-delrrsive perceptual situations

2c,6 MIND'S KNOWLEDGE OF EXISTENTS and with normal human observers whose bodies are in a healthy state, we can drop the independently necessary conditions out of account, and confine our attention to these dependently necessary and common external conditions. This of course is what the physical theories of colour and temperature do. Naturally such theories are incomplete, since they presuppose the fulfilment of conditions which are not always fulfilled. But, when we try to complete them we have to do so, not by ascribing a physical colour or temperature in a literal sense to the external conditions, but by considering the structure and processes of the observer's body. Thus, whilst it is not impossible that physical objects may literally have colours and temperatures, there is not the slightest reason to believe that they do. It is of course quite easy to def,ne a Pickrvickian sense in which a certain physical object may be said to have a certain physical colour. I have already done this in t r eat ing t h e M u l ti p l e In h e re n c e T h e ory, and i t i s perfectly easy to give a similar definition, nutatis mutandis, on the other trvo theories. But this is quite a different thing from saying that a physical object literally has a certain colour, in the sense in which the objective constituents of visual situations have colours. I do not know that I have ever seen a satisfactory def init ion o f th e te rm s t' P ri ma ry " and t' S econdary " It will therefore be of interest to try to give Quality. one. I suggest thc following definitions. "A Primary Quality is a determinable characteristic which, we have reason to believe, inheres literally and dyadically in some physical object in some determinate form or other." " A Secondary Buality is a determinable characteristic rvhich certainly inheres or seems to inhere literally and dyadically in the objective constituents of some perceptual situations in some determinate form or other, but which there is no reason to believe inheres literally A primary and dyadically in any physical object." quality may, but need not, inhere literally and dyadic-

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ally in some objective constituent. On these definitions, colour and temperature are secondary qualities, if I am right about their status. Shape, size and position are pri mary qual it ies r vhich inher e lit er ally and dyadically both in the objective constituents of perceptual situations and i n thei r r elat ively per m anent condit ions. Elect r ic charge, magnetic properties, and so on, are primary qualities which inhere literally and dyadically in physical objects, but do not (so far as we know) inhere in the objective constituent of any perceptual situation. B efore ending t his sect ion it will be int er est ing t o see just rvhere Locke and Berkeley were respectively right and wrong, on our vierv, about primary and secondary qualities. Berkeley rvas right against Locke when he said that nothing could possibly be merely extended and movabl e. (Though Locke, t o do him just ice, never mai ntai ned anyt hing so silly as t he pr oposit ion which Berkeley refutes.) This may be expressed by saying that, zf spatio-temporal characteristics be primary, they cannot be tleeonl1t primary characteristics. Whatever is extended must have sotne other characteristic, which is r:apable of covering an area or filling a volume as colour and temperature do in sensa. But Berkeley lvas wrong .i rr thi nki ng that t his , . ext ensible char act er ist ic", as I rvill call it, must be colour or temperature or sorne other qual i ty w hi ch lit er ally and dyadically inher es in sensa. It might be mass or electric charge. Again, Berkeley rvas right in so far as he held that there is just as good rcason to deny that the determinate shapes and sizes of sensa inhere literally in some permanent object, w hi ch w e are said t o be . . seeing", as t o deny t hat t he determinate colours or temperatures of sensa literally inhere in such objects. But Locke rvas right in so far as he held that there is positive reason to hold that the determinable characteristic of extension inheres literally and dyadically in physical objects as rvell as in sensa, rvhilst there is no reason to believe that the determin;rble characteristics of colour and temperature inhere

2O8 MIND'S

KNOWLEDGE

OF- EXTSTENTS

l it er ally and d y a d i c a l l y i n a n y th i n g b u t sensa. A nd s o Loc k e was ri g h t i n th i n k i n g th a t w e can and must dis t inguis h be tw e e n p ri m a ry a n d s e c o ndary qual i ti es, a nd he was r ig h t i n a s s i g n i n € f e x te n s i o n a nd moti on to the former class, and colour and temperature to the latter. Both these great men rvere thus expressing important truths; but they both expressedthem imperfectly, because they failed to notice certain important distinctions which we, who have the advantage of standing on their shoulders, are able to see. The Subjective Factors in Perceptual Situations. I have been considering the belief, rvhich forms an essential factor in every perceptual situation and constitutes its external reference, from a logical and epistemological and not from a psychological point of vierv. By this I mean that I have been concerned with the pr opos it ions be l i e v e d a n d n o t w i th th e a c t of bel i evi ng them. I have tried to state clearly rvhat these propositions are ; to consider rvhich of them are certainly false and which of them are possibly true ; and to adduce and appraise the evidence rvhich can be submitted in favour of the latter. I propose to end this chapter by an attempt at further psychological analysis of the perceptual situation. The remarks which I shall norv make are to be regarded as a continuation of theanalysis which rvas begun and carried a certain length in the sub-section on Ertental Reference. I there rvarned the re ader of t he fo l l o rv i n g p o i n ts . (i ) T h at the bel i ef which constitutes the external reference of a perceptual situation is not in fact reachedby inference, even if it can be defurded by inference on later reflection. (ii) That , ps y c holo g i c a l l y , i t c a n o n l y b e c a l l ed a " bel i ef " by courtesy. We can only say that a man in a perceptual situation acts, adjusts his body, and feels certain e m ot ions ; and th a t th e s e a c ti o rl s , a d j ustments, and emotions are such as would be reasonable if he were ex plic it ly m ak i rrg s u c h a n d s u c h j u d g m e nts, rvhi ch he

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does not in fact make as a rule at the time. The bodily adiustment itself is of course no part of the subjective factor in the perceptual situation ; but it is impossible to make these adjustments or to start to perform these actions rvithout producing certain characteristic modifications of bodily feeling. These modifications of bodily feeling and these emotions are an essential part of the subjective side of every perceptual situation. We have norv to see whether we can carry the analysis any further. A refl ecti ve o bser ver , consider ing one of his own perceptual situations after it has ceased, or considering a contemporary perceptual situation in which he is not personally concerned, rvould probably propose the following analysis for it. (i) An objective constituent, havi ng certai n se nsible qualit ies and f or m ing a dif f er entiated part of a rvider sense-field. (ii) A subjective consti tuent, cons ist ing of a m ass of bodily f eeling, emotion, etc. (iii) The fact that this objective consti tuent i s i ntui tively appr ehended by t he per cipient . (iv) The fact that the percipient, rvho intuitively apprehends the objective constituent and who feels the emotions and bodily feelings, has certain non-inferential beliefs about the objective constituent rvhich go beyond anythi ng that i s int uit ively appr ehended in t he sit uat ion. I believe this analysis to be substantially correct' though the fourth factor in it is expressed in terms rvhich do not strictly apply to anything so primitive as the perceptual situation but are borrowed from higher cognitive levels. I have already discussed the first factor ad ,tdt4sedrn,and I have already given my reasons for w i shi ng to modi f y t he st at em ent of t he f our t h. What I rvant to do now is to explain what I suppose to be i nvol ved i n the int uit ive appr ehension of t he object ive r:r> nsti tuentand in t he quasi- belief about it . I t hink that the tw o are pr obably ver y closely connect ed. It is quite T'/re httuitiz,e Apqsrehension oif Setsa. r:r:rtain that there is a difference between the two

2O8 MIND'S

KNOWLEDGE

OI" EXISTENTS

lit er ally and d y a d i c a l l y i n a n y th i n g but sensa. A nd s o Loc k e w a s ri g h t i n th i n k i n g th a t w e can and must dis t inguis h b e tw e e n p ri ma ry a n d s e condary qual i ti es, and he was ri g h t i n a s s i g n i n g e x te n s i on and moti on to the former class, and colour and temperature to the latter. Both these great men rvere thus expressing important truths; but they both expressed them imperfectly, because they failed to notice certain important distinctions which we, who have the advantage of standing on their shoulders, are able to see. The Subjective Factors in Perceptual Situations. I have been considering the belief, rvhich forms an essential factor in every perceptual situation and constitutes its external reference, from a logical and epistemological and not from a psychological point of vierv. By this I mean that I have been concerned with the pr opos it ions b e l i e v e d a n d n o t w i th th e act of bel i evi ng them. I have tried to state clearly rvhat these propositions are ; to consider rvhich of them are certainly false and which of them are possibly true ; and to adduce and appraise the evidence rvhich can be submitted in favour of the latter. I propose to end this chapter by an attempt at further psychological analysis of the perceptual situation. The remarks which I shall norv make are to be regarded as a continuation of the analysis whic h r v as b e g u n a n d c a rri e d a c e rtai n l ength i n the sub-section on Erterual Reference. I there rvarned the reader of the follorving points. (i) That the belief which constitutes the external reference of a perceptual situation is not in fact reochetlby inference, even if it can be deftnded by inference on later reflection. (ii) T hat , ps y c h o l o g i c a l l y , i t c a n o n l y b e cal l ed a " bel i ef " by courtesy. We can only say that a man in a perceptual situation acts, adjusts his body, and feels certain em ot ions ; a n d th a t th e s e a c ti o rrs , a dj ustments, and emotions are srrch as would be reasonable if he were ex plic it ly m a k i n g s u c h a n d s u c h j u d g ments, rvhi ch he

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2og

does not in fact make as a rule at the time. The bodily adiustment itself is of course no part of the subjective factor in the perceptual situation ; but it is impossible to make these adjustments or to start to perform these actions rvithout producing certain characteristic modifications of bodily feeling. These modifications of bodily feeling and these emotions are an essential part of the subjective side of every perceptual situation. We have now to see whether we can carry the analysis any further. A reflective observer, considering one of his own perceptual situations after it has ceased, or considering a contemporary perceptual situation in which he is not personally concerned, rvould probably propose the following analysis for it. (i) An objective constituent, having certain sensible qualities and forming a differentiated part of a rvider sense-field. (ii) A subjective consti tuent, consist ing of a m ass of bodily f eeling, emotion, etc. (iii) The fact that this objective consti tuent i s i nt uit ively appr ehended by t he per cipient . (iv) The fact that the percipient, rvho intuitively apprehends the objective constituent and who feels the emotions and bodily feelings, has certain non-inferential beliefs about the objective constituent rvhich go beyond anythi ng that is int uit ively appr ehended in t he sit uat ion. I believe this analysis to be substantially correct, though the fourth factor in it is expressed in terms rvhich do not stri ctl y ap ply t o anyt hing so pr im it ive as t he per ceptual situation but are borrowed from higher cognitive levels. I have already discussed the first factor ad ,tttusearn,and I have already given my reasons for wishing to modify the statement of the fourth. What I rvant to do now is to explain what I suppose to be i nvol ved i n th e int uit ive appr ehension of t he object ive r:onsti tuent an d in t he quasi- belief about it . I t hink that the two are probably very closely connected. It is quite T'he Inluiliz,e ATtprehension o1f Sensa. cr:rtain that there is a difference betrveen the two

2IO

MIND'S

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OF EXISTENTS

propositions : " This is a red round patch in a visual field " and " This red round patch in a visual field is E ven i f as a int uit iv ely a p p re h e n d e d b y s o -a n d -s o" . matter of fact there are no such objects which are not intuitively apprehended by someone, it seems to me to be perfectly certain that it is logically possible that there might have been. (I have argued earlier in the chapter that it is also causally possible, but it is not necessary for our present purpose that this should be so.) Since it is logically possible that the same sensum should s om et im es b e i n tu i ti v e l y a p p re h e n d e d and someti mes not, or that it should sometimes be intuitively apprehended by A and not by B and at other times by B and not by A, it seems plain that the characteristic of being " i n tu i ti v e l y a p p re h e n d e d " i s a rel ati onal c har ac t er is t i c ; i .e ,, th a t i t c o n s i s ts i n t he establ i shment of a certain asymmetrical relation R between the sensum and s om et hin g e l s e . T h e q u e s ti o n i s : r' W hat i s thi s relation, and what is this something else ? " A theory has been put forward by the persons rvho call themselves " New Realists ", which would provide a simple ans wer t o t hi s q u e s ti o n i f i t c o u l d b e a ccepted. It has also been suggested by Mr Russell, and is therefore worth a degree of attention rvhich it rnight not otherwise have deserved. So far as I can understand the theory it comes r oughly t o t h i s . Al l th e v i s rra l s e n s a o f w hi ch i t w oul d be true to say that A intuitively apprehends them belong to a certain visual field. And of all sensa which belong to this visual field it would be true to say t hat A int ui ti v e l y a p p re h e n d s th e m. H ence the tw o pr oper t ies of " b e i n g i n tu i ti v e l y a p p re hended by A " and " belonging to a certain visual field " are logically equiv alent . M o re o v e r, th e re l a ti o n o f a sensum to a s ens e- f ield is a s y m m e tri c a l . It i s th e n suggested that really we have not two differcnt though logically equivalent properties, but a single property rvith trvo different names. To say that " The visual sensum s is

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2TI

rrrtrri ti vel y apprehended by A" , ileans t he sam e as t o s;r;' that ttThe visual sensum s belongs t o a cer t ain vi srr;rl fi el d ,f^. " I f t his r ver e t r ue, t he " som et hilg tl sr: " to w hi ch a sensum is r elat ed when it is int uit ively ;tl rprchended w ould be a cer t ain sense- f ield; and t he ' rsvrrrmetri cal re lat ion of being int uit ively appr ehended rvorrfcl be that of a part of a sense-field to the sense-field ,rs :r w hol e. It scems to me perfectly certain that this theory is l ,rl sc. (a) N o one would adm it t hat a sensum which \v;rs part of a sense- f ield r vhich is not int uit ively i rpl )l chcnded would it self be int uit ively appr ehended. l l crrr:r:w e can ho ld t hat " t o be int uit ively appr ehended " rrrrrl "to belong to a sense-field" tttean the same only if wt irrlrnit that it is logicallT impossible for there to be a r,r.rrsr.-l i r:lwdhi ch is not int uit ively apyr r ehended. Nor v rt i s r;tri te pl ai n t hat t her e is no m or e logical im possil ri l i ty i n the exist ence of an unappr ehended sense- f ield l l rnrr i n the exi st ence of a single sensu'. n which is not Hence " t o be int uit ively Irrtrri ti vcl y appr ehended. n;r;rrr:l rcnded" and " t o belong t o a sense- f ield" cannot rrrri rrrthe same. ( D) A visual sensum , a t act ual sensum , rrrrrl ;ur audi tor y sensum m ay all be int uit ively apgrr,' l rr,ndcdby the sam e per son at t he sam e t im e. They r r.rl ;ri rrl y do not all f or m par t s of any one sense- f ield. l l rrrl r,, to be int uit ively appr ehended by a cer t ain l r,r:i ()n crrnnot b e t he sam e as t o f or m par t of a cer t ain nr,rr,;r.-fi cl d.S till, it is no doubt t r ue t hat t her e is sont e rr.l rrti orrbetrvee nt hose sensa r vhich would be said t o be Irrtruti vr,l yappre hended by t he sam e per son, which does rr,rl l rol tl betw e en sensa r vhich would not be said t o be trrtrri ti vt:l yappre hended by t he sam e per son. M ight it rrot l rc srrggeste dt hen t hat t he t heor y is r ight in out line, tl rorr;,gl irn< ;orrectas or iginally st at ed? We m ay adm it f l r,rt " to l rc i rrtuit ively appr ehended" is not t he sam e as " ro l )r. rrni tcd wit h cer t ain ot her sensa so as t o f or m rutl r tl rcrrr :r < : er t ain sense- f ield" I but m ight r ve not tl r:tt i t rs t he sam eas "t o be unit ed wit h cer t ain ' ,rr1,s,r' .,t

2T2 IIIND'S

KNOWLEDGE

OF EXISTENTS

R mi ght be a ot her s ens a b y a c e rta i n re l a ti o n R " ? quit e unique re l a ti o n , i n c a p a b l e o f fu rther anal ysi s or definition ; but it rvould have to have the follorving pr oper t ies . (r) It mu s t b e l o g i c a l l y possi bl e for a set of sensa which are not all parts of a single sense-field to be related to each other by the relation R. (z) R must be such that trvo sensa, each of rvhich is related by R to so,ueother sensa, need not be related by R to each other. F or t her e a re s e n s a w h i c h a re i n tu i ti vel y apprehended by A and not by B, and there are sensa rvhich are The int uit iv ely a p p re h e n d e d b y B a n d not by A . m odif ied t he o ry th e n c o m e s to th i s . There i s a certai n r elat ion R w h i c h b i n d s c e rta i n s e n sa together i nto T o b e intui ti vel y apprem ut ually ex c l u s i v e g ro u p s . o f s o me group o[ sensa me mb e r b e a to m ea n s hended re l a ti o n R . Let us consi der th e b y bound t oge th e r form. this theory in its modified So long as the theory is content to regard the relation R as abs o l u te l y u n i q u e a n d p e c u l i a r I do not thi nk t hat it c an b e p o s i ti v e l y re fu te d . The moment i t at t em pt s t o i d e n ti fy R rv i th s o m e fa m i l i ar rel ati on, such as compresence in a sense-field or a direct relation of s im ult aneit y , i t i s p l a i n l y fa l s e . It i s o bvi ousl y l ogi cal l y possible, e.g., that a set of sensa should be directly simultaneous with each other and yet that none of them s hould be i n tu i ti v e l y a p p re h e n d e d . B ut, al though I c annot r ef u te th e th e o ry s o l o n g a s i t i s rvi l l i ng to take R as abs o l u te l y u n i q rre a n d p e c u l i ar, I thi nk I can prove that it fails to account for a certain obvious fact so well as alt e rn a ti v e th e o ri e s , a n d th a t t he moti ves rvhi ch led to it are connected with an erroneous belief. This I will norv try to shorv. (a) lf the theory be a complete account of the facts, t he unit y o f a s e t o f s e n s a rv h i c h a re al l i ntui ti vel y appr ehende d b y a c e rta i n p e rs o n i s rvhol l y a " ttni ty of I shal l have to s y s t em " an d n o t a " tl n i ty o f c e n tre " . detai l rvhen i n g reater o f u n i ty ty p e s trv o t he s e c ons ider I rvi l l pr:esent At th e Se l f. o f u n i ty th e I c ons ider

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2r3

(:ol rtcnt mysel f rvit h saying t hat a f am ily of br ot her s ;rnd si sters i s an exam ple of a unit y of cent r e. The lcl:rtions rvhich they have to each other are due to the firt:t that they all stand in a common relation to somel hi rrg (vi z., thei r par ent s) which is not it self a m em ber of the set. The point s on a st r aight line const it ut e a prrrc uni ty of sys t em ; t hey ar e just dir ect ly r elat ed t o r.;rt:h other by th e r elat ion of ( 'bet r veen ", and t his rcl ati on does not depend in any t vay on t heir all being l r' l ated by some com m on r elat ion t o som et hing r vhich is n(,1 a member of t he set . Now it is per f ect ly cer t ain l l r;rt rve al l bel i eve, t o st ar t wit h, t hat t he unit y of a set ol sr:nsa w hi ch ar e all int uit ively appr ehended by t he tjulc person is a unity of cenlre and uot a pure unity of system. That t his is so is pr oved conclusively by l rrnguage, and by t he ext r em e air of par adox which t he l rl l l xrsi te vi erv con t inues t o pr esent even r vhen we adm it tl rrrt i t i s l ogi cal l y possible. I t is cer t ainly a f act t hen l l urt, r/' the uni ty o f a set of sensa int uit ively appr ehended l ry tl rt: same perso n be in f act a pur e unit y of syst enr , it rtr.vr.rt-lreless afpeors, and goes on appearing, to be a rrrti ty of centre. This f act m ust be r ecognised and alr'orrnted for on any adequate theory of the subject. N orv rny obj ecti on t o t he t heor y under discussion is t hat i t rrttr:rl y fai l s to account f or t his appear ance. We m ust l r.rrtcrrrl l erthat ev er y unit y of cent r e is also a unit y of ny\tr.fn. l f r, y, and . c all st and in a cer t ain unique rr,l ;rti on S to a ce r t ain t er m 1 t her e r vill be an unique, f l rrrrrgl r deri vati ve, r elat ion bet r veen r , - t ', and s. For r w ,i fl l rave to t th e r elat ion R of " being bot h of t hem l r.rrrrs rvhi t:h stan d in t he r elat ion S t o / ". And, qrrrl r S i s uni que, R r vill be unique. Thus it is quit e gro..ri l rk:that rvha t is in f act a unit y of cent r e m ight rl l )l x.;i l ' tri be a pur e unit y of syst em , especially if t he ' r r r.ntrc " / rvr-' resuch t hat it is har d t o det ect and easy Irr uvr.rl ool i . IJut t her e is no r eason t vhat ever r vhy r vhat 1,,i rr l ,l tct i r l )ure unit y of syst em should appear t o be a rrrr,rtyol ( ot)tre. Hence it seem s t o m e t hat t he t heor l,

2r4

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OF EXISTENTS

u nder dis c us s io n i s q u i te i n c o mp e te n t to expl ai n a most st r ik ing and pe rfe c tl y i n d u b i ta b l e fa c t. I shoul d therefore co-nsiderit absurd to accept such a theory unless ther e r v er e ins u p e ra b l e o b i e c ti o n s to th e a l ternati ves or These claims rvould be great advantages in itself. but I believe that they theory present the for ; irade try to shorv' now I rvill justification, as have no of this theory supporters which (D) The objection l a tter i nvol ves a th e i s th a t v i e w m ak e t o t he op p o s i te tt Pure Ego " to be the " centre " which generates the unit y . ena it i s s u p p o s e d th a t a " P u r e E go " i s so disreputable that no decent philosopher would allorv s uc h a t hing i n h i s mi n d i f h e c o u l d p o ssi bl y hel p i t' I shall have to deal rvith the alleged indecency of the Pur e E go in a l a te r c h a p te r; h e re I wi l l merel y say th at t he objec t i o n i s q u i te i rre l e v a n t b e c ause there i s no need whatever for the unifying centre to be a Pure Ego' It m ight be, an d I b e l i e v e i s , a m a s s o f bodi l y feel i ng' O f c our s e, lat e r o n , q u e s ti o n s mu s t b e rai sed about the {' or v ner s hip" o f th i s m a s s o f fe e l i n g ; and then w e m ight f ind t h a t th e Pu re Eg o T h e o ry expl ai ned the facts better than any other. But, so long as we are m er ely c onc e rn e d w i th th e i n tu i ti v e a pprehensi on of ,"nr", it is perfectly ridiculous to try to frighten us into t he t heor y und e r d i s c u s s i o n b y th re a te n i ng us w i th tl te P ur e E go as a k i n d o f b o g e y w h i c h c a n be exorci sed tt Nerv Realism "' only by a cotlrse of which is claimed for 1r; i ttrint< that the advantage n a tu ra l i s ti c " ' ' l ' hi s, I thi nk, i t i s is t h a t t he t heor y " means roughly that it claims to be able to deal rvith m ind r v it hout i n tro d u c i n g a n y n e l v a n d uni que enti ti es or relations. I have already shorvn that the opposite theor y has no i mme d i a te n e e d o f a n y very mysteri ous s pec ial ent it y , s u c h a s a P u re E g o ' T here shoul d be not hing v er y t ry i n g ' e v e n to th e mo s t s e n si ti vel y natural is t ic m ind, in a m a s s o f b o d i l y fe e l i n g ' A nd I cl ai m also to have shorvn that the theory cannot dispense r v it h an uniq u e k i n d o f re l a ti o n . If y o u i denti fy the

SENSE-PERCEPTIONAND I\IATTER

2rs

relation R rvith any familiar relation it is perfectly obvi orrs that ,.to b e int uit ively appr ehended', does nit nlean ttto be a member of a group of sensa interrelated by R ". On the rvhole, then, it seems to me that there :trc grave objections to the theory under discussion and no advantages to outweigh them. I therefore reject it, ;rrrd accept the common-sense view that rvhen a visual, tactual , or audi tory sensum is int uit ively appr ehended i t stands i n an un ique kind of r elat ion t o som et hing rvl ri ch i s not an audit or y, t act ual, or visual sensum . A nd I bel i eve this . . som et hing " t o be t he m ass of general bodily feeling of the percipient at the t i l nc. T'hc quasi-Belief obout the Sensunt I am inclined to tl ri nk that the qua si- belief about t he object ive consti tuent, rvhi ch i s t he f our t h dist inguishable f eat ur e in it perceptual situation, consists in the fact that certain ::1tnific bodily feelings (connected rvith the automatic rrrl .j ustnrentof the body) , cer t ain em ot ions, and cer t ain fer.lirrgsof expectition, are related in an unique way to tl rr: :rpprehended se nsum . These ar e causallydependent ol r the traces l eft b y past exper ience. When a sensum of a speci fi c ki nd is int uit ively appr ehended cer t ain l ri l r:cs are exci ted; t hese ar ouse cer t ain em ot ions and i rrrl rrr:t:certai n bod ily adjust m ent s r vhich ar e accom -

l l rr. rrl l prehensi on o f t he sensum do not just coexist rvrtl r i t; they i mmediat ely ent er int o a specif ic kind of rr,l rrti on to i t, rvhi c h I do not knor v how t o analyse l rrrtl rr.r. A nd these . . m nem ic consequences" in t his r;rr,r' i l i r:rel ati on to t his int uit ively appr ehended sensum I rn\ti l rrtc the quasi - belief about t he sensum , which gives tl rr, si t rr.l ri on i ts s pecif ic Ext er nal Ref er ence. Any ' rrtu,tti ()nctl nstructed of such m at er ials in such r elat ions, tf " , /,r,7' ,,Il as such an d such an Ext er nal Ref er ence. This

2T6 MIND'S

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is the best analysis that I can offer at present of the typical perceptual sittration. It r ais es one in te re s ti n g q u e s ti o n . C a n th ere be pure sensation without perception ? Let us see exactly what th i s m eans on ou r th e o ry . A p u re s e n s a t i on w oul d be a s it uat ion in r v h i c h a c e rta i n s e n s u mr e .g.t a noi se or a c olour ed pat c h , w a s i n tu i ti v e l y a p p re h e n ded, but i n rvhich there 'ivas no external reference. Now, on our th e or y , we s hou l d e x p e c t p e rc e p ti o n to m e l t i nto pure se ns at ion by ins e n s i b l e d e g re e s ; w e s h o u l d expect the latter to be an ideal limit rather than an observable fact; and rve should expect it to be unstable and tra n s it or y , if it h a p p e n s a t a l l . If th e mass of feel i ng be highly differentiated and certain specific parts of it b e spec if ic ally r e l a te d to a c e rta i n s e n s u m, rve shal l have a clear case of a perceptual situation rvith a definite external reference. If, on the other hand, the mass of feeling be little differentiated, and the apprehension of the sensum fails to excite traces rvhich cause specific mo dif ic at ions in th e m a s s ' w e s h a l l h a v e a si tuati on rvhic h appr ox im a te s to p u re s e n s a ti o n , s i n c e i ts external reference rvill be very vague. And the same result would happen, even if the mass of feeling were differentiated in the way suggested, provided that for some reason the differentiated parts failed to enter into the p ro per r c lat ion to th e a p p re h e n d e d s e n s u m . It seems to m e t hat r v he n w e a re l o o k i n g a t s o methi ng rvi th interest our arvareness of the sensa torvards the edge of th e v is ual f ield a p p ro x i m a te s to p u re s e n sati on for the first reason. And, perhaps, rvhen rve are looking for so m et hing and d i s c o v e r a fte n v a rd s th a t i t rvas stari ng u s in t he f ac e al l th e ti me , o u r a w a re n e s sof the sensa connected rvith it approximates to pure sensation from the second cause. The Categorial Factor in Sense-Perception. One more p o i nt r em ains t o b e ra i s e d . I h a v e s a i d that' rvhen the q u a s i- belief r v hich i s a n e s s e n ti a l fa c to r i n al l percepttral si tu at ions is f or mu l a te d i n a b s tra c t te rms, i t l nay be

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MATTER

2T7

srrrnmedup i n certain pr oposit ions r vhich I have st at ed lrnrl criticised. I rejected the fourth of these, and rl cl i rnded the fi rst t hr ee by an inver se- pr obabilit y ;rrgtrrnent. B ut, as a m at t er of psychology, I asser t ed l l r;rt the bel i ef i n them was not in f act r eached in t his w i ry. A nd, as a mat t er of logic, I asser t ed t hat t he rrr'1;rrnrentgives them a high final probability only i 1 tl rr.y start w i th a fi nit e init ial pr obabilit y. Her e t hen ;rlc r:r:rtain propositions such that every one acts as if l rr' l rcl i eved them, an d inevit ably goes on act ing as if trr. l l r:l i evedthem, no m at t er what t heor et ical doubt s he nr;ry l i rt:labout them r vhile he is r ef lect ing on t hem . I t rr cr,rt;ri n that they d o not appear self - evident on r el l r,xi orr; that they ca nnot be deduced by self - evident rtr.;rs f' rom premi ses which ar e self - evident ; and t hat l l rr,y r' :rnnot be defended by pr obable r easoning except i l i l l l r(: assumpti on that t hey have a f init e init ial pr obrrl ri l i t.y. I cal l such a set of pr oposit ions a set of " Itostrrl ates" ] B etween t hem t hey , , def ine " a cer t ain F' rrrr.r;rlooncept, vi z. t he not ion of a Physical O bject . l " or ;1 l l l l ysi cal obj ect just is som et hing t hat answer s t o l l tr. c postul ates. A gener al concept which is def ined i rr tl ri s w ay by a set o f post ulat es such as I have been rfrrr ri l ri rrg, I cal l a t . Cat egor y". Fr om t he ver y r,rl ur(. of the case the not ion of , , Physical O bject " r,l nnot l r;rve been derived by abst r act ion f r om obser ved i rrrt;rrrccsof i t, as the not ion of , , r ed" no doubt has Irr.r,rr. l i or the obj e ct ive const it uent s of per cept ual cl l rr,rti ons trc not i ns t ances of t his concept ; and it is urrl 1,rrr vi rtuc o[ these post ulat es t hat we can hold t hat l l rr,!' ;rrc " l tarts of " or , , m anif est at ions of t ' inst ances tI t l ri s r' orrcept. The concept is not , ( got out of " l l pr' r r(.nc(.rrnti l i t has been r . put int o " exper ience. I t l !, l rr' ,,trl r.sr;ri bedas an innat e pr inciple of int er pr et at ion ul rr, l r rvr. aJl pl y to the dat a of sense- per cept ion. At l l rr, l rrrrcl ,y Jl erceptua l level r . t o apply t he pr inciple " .,rrrrpl 1,rn(' :l n.sto act and t o f eel as it would be r eason,rl rl r' to;r{' l ;l nd feel i f r ve explicit ly r ecognised it and

2T8 MIND'S KNOWLEDGE OF EXISTENTS int er pr et ed t h e d a ta o f s e n s e i n a c c o rd a nce rvi th i t. It is only at t he re fl e c ti v e l e v e l th a tw e c a n state i n abstract t er m s t he im p l i c a ti o n s o f rv h a t w e h a v e al l been doi ng all our liv es . Summary and Conclusions. In this chapter I have been c onc ern e d rv i th tw o v e ry d i fl i cul t questi ons : t t W hat m ay w e b e l i e v e a b o u t o tl r o w n bodi es and about t he exte rn a l rv o rl d ? " a n d " W h at i s the mi nd r eally doing rv h e n i t i s s a i d to b e p e rc ei vi ng a materi al object ? " On the first point I have reached the follorving t ent at iv e c onc l u s i o n s . (r) We m a y b e l i e ve that there are relatively permanent objects rvhich literally have shape, s iz e, and pos i ti o n ; w h i c h s ta n d i n l i te ral spati al and t em por al r ela ti o n s to e a c h o th e r ; a n d w hi ch l i teral l y move about in Space. (z) We may believe that some of t hem ar e a n i m a te d b y mi n d s ; a n d that any one of t hem whic h i s a n i m a te d b y a mi n d mani fests i tsel f to t hat m ind in a p e c u l i a r w ? /r v i z .rb y o rg ani c sensati ons. Not hing m an i fe s ts i ts e l f i n th i s rv a y except to the m ind, if t her e b e o n e , w h i c h a n i ma te s i t. (3) W e may believ e t hat p h y s i c a l o b j e c ts , w h e th e r a ni mated or not, m anif es t t hem s e l v e s i n a v a ri e ty o f w a y s to mi nds w hi ch do not anim a te th e m. An d w e ma y bel i eve that a s ingle phy s ic a l o b j e c t m a y m a n i fe s t i tsel f at the same t im e in t he s a m e o r i n d i ffe re n t w a y s to a number of m inds anim at i n g b o d i e s i n v a ri o u s p l a c e s. (4) W e may believ e t hat , b y c o m p a ri s o n o f th e o b j e cti ve consti tuents of various perceptual situations and by reflexion on t heir c or r elat i o n s , w e c a n d e te rm i n e w ith hi gh probabilit y t he s h a p e , s i z e , a n d p o s i ti o n o f the physi cal Ancl object which manifests itself in this situation. rvith somervhat less certainty we can determine important facts about its microscopic structure and the m ov em ent s o f i ts mi c ro s c o p i c p a rts . (5) W e must believe that a physical object has other properties beside it s pur ely s pa ti o -te m p o ra l o n e s . It m u st have at l east one qualit y w h i c h i s c a p a b l e o f l i te ra l l y coveri ng an

SITNSE-PERCEPTION

AND

IIATTItR

2r9

i l rca or fi l l i ng a volum e; and it m ay have m any such. (tr) W e may not believe t hat t he object ive const it uent s ol ' l l erceptual si tuat ions ar e lit er ally spat io- t em por al lxtrts of the physical objects rvhich we are said to be pcrcei vi ng i n tho se sit uat ions ; or t hat in gener al t hey lrrrve the same determinai'e spatial characteristics as the scnsa by rvhich they manifest themselves. (7) We ha-ve n(, rc:rsonto bel i e ve t hat physical object s have t he sam e < l cl c.rrni uabl csensible qualit ies as t he sensa by r vhich llrr:y rrranifestthemselves. (8) \\re may ilot believe that t f rc shape, si ze, spat ial posit ion, dat e, or sensible rl rr:rl i ti cs of a sensum by r vhich a cer t ain physical olr,jrrr:tmanifests itself are direcl[, determined by this pl rysi < :alobj ect or by pr ocessesin it . O n t he cont r ar y llrr tntlependentlynecessary and sufficient conditions of rrl l these character ist ics of t he sensum ar e r vit hin t he rrgi on occupi ed by t he per cipient 's body. At best t he cxtl l n:rl physi caf object and t he pr ocesses in it ar e I r'fn()to and depcndettl-t, necessary conditions of the :.,r'nsunrand its characteristics. (9) We have, therefore, l rr rcr' ogni sea pe culiar kind of t r ans- physical causat ion, rrl cortl i ng to rvhich t he occur r ence of cer t air l event s in a r rt l ;ti tt brai n and ner vous s) 'St em det er m ines t he occur rrrrr' r' r)f a sensum r vit h st r ch and such a shape, size, p,rsi ti ol r, and se nsible qualit y, in a cer t ain sense- f ield ol ,;r t:r' rtai n sense- lt ist or y. ( r o) We have t o adm it l l r;rt ccrtai n charact er ist ics of cer t ain sensa ar e pr r r bably 11' t t' orn1)l etel y det er m ined by physical and physiol ngi r' ;rl cvents i n t he body of t he per cipient ; but ar e in ;r,rrt rl r:termi ned, eit her dir ect ly or indir ect ly by event s rrr tl rr: rni nd rvhi c h anim at es t his body. ( )rr tl rc second point I have r eached t he f ollor ving tl rl ;rti vr: t:oncl u sions. ( t ) The per cept t r al sit uat ion r ,rrrt.ri rrstrvo con st it uent s, one object ive and t he ot her ' ,rrl jr.r' ti vt:. (e) The object ive const it uent is a sense( - l) The l rr' l rl rvi th a cer t ain out st anding sensum . ,,rrl r1r'tirvc const it uent is a m ass of bodily f eelir r g, r, rt,r' l l rcr rvi th cer t ain specif ic em ot ions, m uscular

22O MIND'S

KNOWLEDGE

OF EXISTENTS

sensations, feelings of familiarity, images, etc. (4) The latter are produced through the excitement of certain traces by the apprehension of the sensum. (5) The se n s um is appr eh e n d e d b y e n te ri n g i n to a certai n specific relation rvith the general mass of bodily feeling. (6) The situation has a certain specific external reference in virtue of a certain specific relation between the tt a p p re hended s ens u m a n d i ts m n e m i c c o n s equences" in the rvay of feeling, etc. (Z) lt seems likely that pure sensation is an ideal limit, which is approached as the external reference grows vaguer and vaguer, rather than an observable fact. (8) The notion of Physical Object cannot have been abstracted from the data of sense. It is a Category, and is defined by Postulates.

CHAPTER

V

Memory ' l ' l tr: w ord " memory " is highly am biguous, even when it is not being used in admittedly paradoxical and un('()rnmon senses, as when people talk of tt racial " or " itncestral " memory. I call such uses of the word paradoxical because even those persons who hold that itr ;rcrforming an instinctive action we are t.trememberittg " similar actions which were performed deliberately lry our remote ancestors would have to admit that, in l l tc < l rdi nary sense of tt r em em ber ing", we cer t ainly do n()t r(:member the actions or thoughts of our ancestors. l i vr.rr apart from these odd senses of t t m em or y" it is rgrritr:t:crtain that the rvord covers a number of very rl i l l i .rr:nt acts. W e talk of r em em ber ing a set of n(' nsr.nse-syl l abl es I of r em em ber ing a poem ; of r errrr.rrrl xrri nga proposi tion in Euclid, t hough we have ftrrgotten the words in which it was expressed when w r, ori gi nal l y l earnt i t ; of r em em ber ing past event s I nrrrl of rernemberi ng p eople, places, and t hings. To rrrrrrnl l )t:ra set of nonsense- syllables is m er ely t o have nl rl rri rcrl the pow er of r epeat ing t hem at will ; and rr,rrrr.rrrl rr:ri ng, i n thi s sense, seem s t o be no m or e an rrrI ol r:ogrri ti on than i s t he act of r iding a bicycle or of trvi rrrrrri rrg. To remem ber a pr oposit ion of Euclid is l rr rl orrl rt t< t perform a genuine act of cognit ion; and l l rr. ,i ,;rrrrc i s true of remem ber ing event s, per sons, and Irl,rrr.s. llrrt the first kind of. act has an abstract and tl nrr.l (.ssobj ect; rvhi l st t he second has a concr et e par ttr rrl ,rr ol l .i cr:trvhi ch exist s in t im e. Pr esum ably t hen tl rl rrrr.rnoryof proposi t ions is som et hing quit e dif f er ent Ir,' rrr tl tt rncmory of m er e sent ences,on t he one hand,