per(op)relativity preceptual knowledge

8/14/2019 Per(Op)Relativity Preceptual Knowledge

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W I L L I A M S. B O A R D M A N

T H E R E L A T I V I T Y O F P E R C E P T U A L K N O W L E D G E

AB STR AC T. S ince the most promis ing pa th to a so lu t ion to the problem of skept ic i smregard ing perceptua l knowledge seems to res t on a sh arp d i s t inc tion be tween perce iv ingand inferr ing, I begin by clar ifying and defending that dis t inct ion. Next , I discuss thechief obstacle to success by this path , :he difficulty in makin g the require d dist inct ionbe tween mere ly log ica l poss ib i l i t i es tha t one i s mis taken and the ' r ea l ' (Aus t in) or' re le van t ' (Dretske) possibi li t ies which would exclude know ledge. I argue tha t this dis t inc-t ion cannot be drawn in the ways Aus t in and Dre tske sugges t wi thout begging thequest ions at issue. Final ly, I sketch and d efen d a more radical way of ident ifying ' re levan t 'possibi l i t ies that is inspired by Aust in 's controversial suggest ion of a paraI lel betweensaying ' I know ' and say ing ~I promise ' : a c la im of knowledge of som e par t icu la r mat te ri s re la t ive to a contex t in which ques t ions about the m at te r h ave be en ra i sed .

.To set the stage for my discussion, I wil l rehearse and clarify a well-known d i spu te be tw een A. J . A yer and J. L . Aus t in concern ing whe the rperceptual judgments are inferences . Both in h is Sense and Sensibiliaand in his O the r M inds , 2 Au stin carefully dist inguishes recognizingthat p f rom inferring that p . Fo r the pu rpose of comp ar ing his posi t ionwith A yer s , we m ight put h is bas ic c la im in th is way: g iven the w aywo rds such as recognize and infer are used outs ide phi losophicaldiscussions, one clearly distinguishes instances of recognizing fro m in-s tances of inferring . Y et A ye r does not d ispute tha t ; ra ther , he repl iesthat whi le non-phi losophers do make a sharp d is t inc t ion between thetwo, i t i s a rb it rary for phi losophical purpo ses . 3 Cla ims based upo n one shaving recognized something are sufficiently l ike claims based uponone s having inferred , A yer supposes , tha t i t is useful to t rea t then: asins tances of a com m on ca tegory . S o the issue is not wh ether the d is tinc-t ion is recognized outside philosophical circles, but whether i t is adefensible and useful one to make. Clear ly , Aust in ins is ts upon thedis t inc t ion because he supposes tha t fa i l ing to make i t wi l l promotephi losophical confusion; indeed, he argues tha t one t radi t ional problemof skepticism is largely due to this confu sion. 4 In his O th er M inds ,Austin tr ies to suggest how recognizing differs from inferring by show-Synthese 94: i45-169, 1993. 1993 Kluw er Acad emic Publishers Printed in the Netherlands


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46 W I LLI A M S BO A RD M A N

i n g h o w t h e s o r t s o f q u e s t i o n s o r c h a l l e n g e s b ro u g h t t o b e a r d i f f e rb e t w e e n t h e t w o s o r ts o f c l a im: 5 fo r i n f e r e n c e s , o n e w a n t s a r e h e a r s a lo f t h e p i e c e s o f e v i d e n c e a n d a n a c c o u n t o f t h e i r c o n n e c t i o n s t o t h ej u d g m e n t ; f o r p e r c e p t u a l c l ai m s o f r e c o g n it i o n, o n e e x p l o r e s w h e t h e rt h e o b s e rv e r h a d t h e o p p o r t u n i t y t o s e e w h a t h e c l a i me d t o h a v e s e e n ,w h e t h e r h e h a d a c q u i r e d t h e e x p e r t i s e to r e c o g n i z e t h e s o r t o f t h in g h ec l a i m e d t o h a v e s e e n , a n d w h e t h e r t h e c i r c u m s t a n c e s w e r e f r e e o fe v i d e n t d i s t r a ct i o n a n d d e fe c t . B u t h is r e a d e r s a p p re c i a t i o n o f t h e s et h i n g s d e p e n d s u p o n t h e i r h a v i n g a l r e a d y g ra n t e d t h a t t h e d i s t i n c t i o ni s no t a rb i t ra ry : s ince Aus t in expec t s u s t o recogn ize tha t t he d i s t i nc t ionis j u s ti f ia b l e , h e d o e s n o t d e f e n d i t ex p li c it ly . A f t e r w e h a v e c o m p a r e dthe two so r t s o f c l a im, we wi l l examine a de fense o f t he d i s t i nc t ionwhich acco rds w i th Aus t in s d i scussion .

W h e n w e t u r n t o a n e x a m i n a t i o n o f cl ai m s b as e d u p o n i n f e r e n c e an do n e s m a d e a s p e r c e p t u a l j u d g me n t s o f r e c o g n i t i o n , w e d i s c o v e r an u mb e r o f i mp o r t a n t s i mil a ri ti e s w h i c h mu s t b e a d d re s s e d b y a n y a c-c o u n t w h i c h i n s i s t s n e v e r t h e l e s s u p o n t h e i mp o r t a n c e o f d i s t i n g u i s h i n gb e t w e e n t h e m .(1) W h e n w e e x p l a in o u r p e r c e p t u a l m i s t a k e s , w e o f t e n d o s o in a w a yw h i c h ma k e s w h a t w e d i d l o o k l i k e a n i n f e r e n c e . F o r w e l i k e t o a r t i c u -l a t e c h a r a c t e r s i n c o m m o n b e t w e e n w h a t w e ( m i s t a k e n l y ) t h o u g h t w esaw and wha t we d id ( in fac t ) see wh ich l ed us to mis t ake one fo r t heo t h e r . A n d t h a t ma k e s i t a p p e a r t h a t w e r e a c h e d o u r (mi s t a k e n ) j u d g -m e n t t h r o u g h a c o ns i d e r a ti o n o f t h o s e c o m m o n f e a t u r e s.(2 ) W h e n w e e x p l a i n h o w w e , u n l i k e o t h e r s p r e s e n t , h a v e b e e n a b l et o s e e w h a t w e d i d s e e , w e a g a in t a l k a b o u t o u r j u d g m e n t a s t h o u g h i tw e r e a s p e c ie s o f i n f e r e n c e . F o r w e p o i n t t o t h e o n e o r s e v e ra l c h a ra c t e r -i s t i c s wh ich enab led us to see wha t we saw.(3 ) I n g e n e ra l , f o r a n y p e rc e p t u a l j u d g m e n t w h i c h o n e ma k e s , t h e r e i sa n i n f e r e n c e w h i c h mi g h t h a v e b e e n ma d e i n t h o s e c i r c u ms t a n c e s a n dw h i c h mi mi c s o r e mu l a t e s t h e p e r c e p t u a l j u d g me n t . B e c a u s e o f t h is ,i f I r e c o g n i z e s o me t h i n g w h i c h y o u d o n t , I ma y p o i n t o u t c h a ra c te r i s ti c swh ich wi l l enab le you to in fe r t ha t wha t I c l a im i s t rue . Th i s fac t abou tp e rc e p t u a l j u d g m e n t s is w h a t e n a b l e s a s e a s o n e d v e t e r a n t o te a c h ab e g i n n e r t o r e c o g n i z e w h a t h can recogn ize . Imag ine t each ing a ch i ldto recogn ize oak t rees : on e wi ll f ir s t po in t ou t t he f ea tu re s cha rac t e r i s t i c


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R E L T I V I T Y O F P E R C E P T U L K N O W L E D G E 147o f o a k s - t h e p a t t e r n s o f t h e i r le a v e s, t h e w a y th e y b r a n c h , f e a tu r e s o fthe i r ba rk , the i r u sua l hab i ta t - in shor t , the so r t s o f th ings f rom w hicho n e s p u p i l m a y in f e r t h a t h e i s s ee in g a n o a k . Ev e n tu a l l y f r o m s u c ht ra in ing the pup i l may lea rn to recognize cer ta in t rees as oaks . So ap e r c e p tu a l j u d g m e n t l o o k s l ik e a v e r y r ap id , u n e x p r e s s e d i n f e r e n ce . I na d d i t i o n , g a in in g n e w in f o r m a t io n c a n e x p a n d o n e s a b i li t y t o r e c o g n izeor see th ings , ju s t a s i t can s imi la r ly expand the number o f in fe renceso n e c a n m a k e .( 4) O n e s c l aim s a b o u t w h a t h e s e es o f t e n i n c o r p o r a t e n o n - p e r c e p tu a lbe l ie f s o r th ings he takes fo r g ran ted , ju s t a s do h i s in fe rences . AsD r e t s k e h a s s h o w n , 6 i f y o u a s k m e w h e th e r t h e w a te r y o u p u t o n t h es tove i s bo i l ing , I may be ab le to see tha t i t i s even though I canno tsee tha t i t i s wa te r wh ich i s bo i l ing : I t ake i t fo r g ran ted tha t the s tu f fin the po t i s wa te r . A nd i f I be l ieve tha t i t is m y ca r wh ich I was see ingth r o u g h th e w in d o w , I c a n p r o p e r ly c l a im to h a v e seen a red -ha i redman s tem my ca r . Because i t i s c lea r tha t a t l eas t pa r t o f such ap e r c e p tu a l j u d g m e n t r e q u i r e s a n i n f e r e n c e ( a n a c t o f t h e f t p r e s e n t in gno un ique v i sua l pa t te rns ) , i t i s t empt ing to suppose tha t the en t i reju d g m e n t m u s t c o n si s t o f i nf e r en c e s .(5 ) As an empi r ica l ma t te r o f (causa l ) f ac t , whenever one recogn izesX as a Y o r th i s a s an X, he mus t be enab led to do so in v i r tue o fce r ta in v i s ib le o r o the rwise ev iden t fea tu res o f the th ing he sees o rp e r ce ive s . Ev e n w h e n th e o b s e r v e r c a n n o t i d e n t i f y t h o s e f e a tu re s w h ic he n a b le d h im to p e r c e iv e w h a t h e h a s p e r c e iv e d , n e v e r th e l e s s t h e r em u s t h a v e b e e n e v id e n t f e a tu r e s w h ic h w e r e c a u sa l ly n e c e s s a r y f o r h isp e r c e p tu a l j u d g m e n t . I f I r e a l l y d o recognize m y f a th e r a s h e c o m e sd o w n th e s t r e e t , t h e n h a d c e r t a in o f h is f e a tu r e s b e e n o b s c u r e d b ym a k e u p o r o b s t ac l es , I w o u ld n o t h a v e r e c o g n iz e d h im . A n d s o i t l o o k sa s t h o u g h w h e n e v e r o n e m a k e s a p e r c e p tu a l j u d g m e n t , t h e r e a r e vi su a l(o r sensory ) cues which wi ll se rve a s the da ta fo r a recons t ruc t io n o fth e p e r c e p tu a l j u d g m e n t a s a n i n f e r e n c e . F o r c l e a r ly , i n s o m e s e n s eo n e m u s t h a v e b e e n w re of those cues , even i f one i s unab le toa r t icu la te them la te r .

Co m p a r e d t o t h e s e im p r e ss iv e s o rt s o f s im i l ar i ty b e tw e e n in f e re n c e sa n d p e r c e p tu a l j u d g m e n t s , t h e differences b e tw e e n th e m lo o k a t f i r s tto be fa i r ly sub t le . In the f ir st p lace , on e can be enab l ed by v i r tue o f


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ce r t a in cha rac t e r i s t i c s v i s ib ly d i sp l ayed by X to recogn ize i t a s a Yw i t h o u t d e l i b e r a t e l y o r c o n s c i o u sl y h a v i n g t a k e n n o t i c e o f t h o s e c h a ra c-t e r is t i cs . Whi l e t he p re sen ce o r avai l ab il i ty o f t hose cues m ay bec a u s al l y n e c e s s a ry t o o n e s s e e in g w h a t h e s e e s, t h e o b s e rv e r m a yn e v e r t h e l e s s b e w h o l l y u n a b l e t o li st t h e m i n a n y h e l p ful w a y ; w h e re a s ,in t he case o f an in fe rence , he mus t be ab le t o l i s t o r adve r t exp l i c i t l yt o t h e d a t a h e h a s u s e d (o r , i f h e h a s a l r e a d y fo rg o t t e n t h e m , h e mu s thave ea r l i e r gon e th rou gh such a li s t) . On e m igh t , o f cou rse , t ry top a t c h u p t h e c o m p a r i s o n b y i n v o k i n g u n c o n s c i o u s l y u s e d d a t a o r i mp l ic i tr e a s o n s , a f t e r t h e m a n n e r o f H a rm a n , 7 P i t c h e r , s a n d p e rh a p s P o l l o c k ; 9bu t t ha t r isks begg ing the qu es t ion a t i s sue . S econd ly , no t on ly m ay ap e r s o n f a il t o m e n t i o n t h e c u e s w h i ch a rg u a b l y h e u s e d i n hi s p e r c e p t u a lr e c o g n i t i o n , o f t e n - w h e n q u e s t i o n e d a b o u t t h e m s p ec if ic a ll y - o n emisdescri es t hose cha rac t e r i s t i c s . Th us , a s is pe r f ec t ly fami l i a r t o u s ,o n e s c l a i m t o h a v e r e c o g n i z e d a f r i e n d a t a p a r t y ma y b e f a r mo rere l i a b le t h a n o n e s r e s p o n s e t o q u e s t i o n s a b o u t h o w t h e f r i e n d l o o k e dor wha t he was wear ing . Ind ee d , i t i s a c ruc i a l fea tu re o f one s ab i l it yt o r e c o g n i z e s o me o n e o r t o s e e t h a t s o me t h i n g i s t h e c a s e t h a t t h ere l i ab i l it y o f h i s pe r cep tua l j udg me n t ou t s t r ip s h i s ab i li t y t o say accu -r a t e l y h o w h e w a s e n a b l e d t o s e e w h a t h e s aw . a S o m e t i me s , t h ep e rc e p t u a l j u d g m e n t i n q u e s t i o n s e e ms t o o s i mp le fo r it s r e l e v a n t c u e sto be spec i f i ed : How indeed i s one enab led to see tha t t he wa l l i sye l low, i f see ing i s rea l ly in fe r r ing? Som et im es , t he d i f fi cu lty is t ha t w edo no t rea l ly have a c la ss if i cat ion schem e o f t he cues wh ich is a s f i ne lyg raded as t he th ings we a re enab led to pe rce ive : one can o f t en t e l l ,f r o m t h e w a y t h e k i t c h e n s me l l s , w h a t i s c o o k i n g , t h o u g h o n e w o u l db e u n a b l e t o d e s c r i b e t h e o d o r e x c e p t a s t h e o d o r o f b u rn t t o a s t o rt h e o d o r o f r o a s t b e e f . A n d s o me t i me s , t h e d i f f ic u lt y s e e ms t o b e

t h e e n o r m o u s c o m p l e x i ty b e h i n d t h e ju d g m e n t . F r e q u e n t l y a p e r s o nacqu i res t he ab i l it y t o t el l tha t h is spouse o r bes t f r i end i s ang ry w i thou tbe ing ab le to spec i fy wha t , i n t hose c i rcu mstan ces , e nab led h im to te l l;a n d e v e n o t h e r s w h o o b s e rv e h i m i n a c t i o n ma y b e h a rd p r e s s e d t ospec i fy the op e ra t i ve cues . Of t en a pa ren t can recogn ize h is chi ld a tg r e a t d i s t an c e s , o r f ro m u n u s u a l p e r s p e c t i v e s , o r f r o m a l a rg e ly o b -scu red v i ew, in a way wh ich de f i e s spec if i c exp lan a t ion . A nd tha t i se x a c t l y t h e f e a t u r e o f a n e x e rc i s e o f a p e r c e p t u a l a b i l i t y w h i c h ma k e si t d i s t inc t f rom an in fe rence : i t s re l i ab i li t y ou t s t r ip s any se t o f i n fe rence sw h i c h h o p e s to e mu l a t e o r r e p l i c a t e t h e w h o l e s e t o f p e r c e p t u a ljudg m en t s wh ich a re exe rc i ses o f t ha t pe r cep tua l ab i li ty . 11


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No doub t when one , say , recogn izes h i s ch i ld f rom a pa r t ia l v iew,the re a re causa l cues wh ich se rve as necessa ry cond i tions ; the p rob le min one s o r so me one e l se s spec i fy ing these cues a r i ses l a rge ly f rom the i rc o m p le x i ty a n d r e d u n da n c y . I m a g in e t h a t a n y o f n u m e r o u s s et s o f fa c ia lfea tu res wi l l enab le a pa ren t to recogn ize h i s ch i ld ; and suppose tha tseve ra l se t s o f these fea tu res a re ava i lab le to the pa ren t in the cu r ren tc i rcumstances ; then he may be ab le co r rec t ly and re l iab ly to recogn izeth is a s hi s ch i ld wi tho u t be ing ab le to iden t i fy tha t se t o f fac ia l cha rac te r -i st ic s wh ich e nab led h im to do so . i2 In fac t , because o f such redun dan cy ,the pa ren t m ay fa l se ly suppose tha t he was ab le to recogn ize h i s ch i ldby on e cha rac te ri s t i c, where as in fac t i t was so me se t o f cha rac te r i s t ic sno t inc lud ing tha t fea tu re wh ich was the bu t - fo r causa l cond i t ion o fh is recogn i t ion . In th i s so rt o f in s tance , the pa ren t s p e rcep tu a l judg-m e n t ( t h a t i s m y c h i ld ) i s f a r m o r e r e li a b le t h a n a n y a t t e m p t b y h imto in fe r the conc lus ion f rom exp l ic i t ly no ted da ta : fo r an in fe rence i son ly a s good as i t s da ta , and in th i s in s tance the da ta wh ich the pa ren ti s ab le to a r t i cu la te do no t conc lus ive ly suppor t the judg me nt tha t hei s see ing h i s ch ild . More over , th e re i s no gua ran t ee tha t an indep end en tinves t iga to r cou ld do be t te r : he migh t conf i rm the re l iab i l i ty o f theparen t s rep ea te d reco gn i t ions o f h is ch ild over t ime an d va ry ing c i rcum-s tances , bu t be un ab le to o f fe r se t s o f causa l ly su f f ic ien t cues wh ichwou ld wi th equa l re l iab il i ty have suppor te d in fe rences rep l ica t ing thep a r e n t s j u d g m e n t s .

Th is shou ld no t be su rp r i sing . W he n ce r ta in cues a re the causa l lysu f fic ien t cond i t ions fo r a pe rso n s be ing ab le to recogn ize som eon e ,then , fo r the ob se rve r to b r ing o f f h is recogn i t ion , i t is no t n ecessa rytha t he be ab le to a r t i cu la te o r adve r t to the cues ; i t i s necessa ry on lytha t they b e in fac t d i sp layed to h im. 13 Unl ik e an in fe rence , the c redi -b i l i t y o f a p e r c e p tu a l j u d g m e n t o f r e c o g n i t i o n d o e s n o t d e p e n d u p o none s be l ie f s abou t h ow he w as ab le to a r r ive a t h i s judg me nt ; a l l tha tis r e q u i r e d is t h a t h e r e l i a bly m a k e t h e j u d g m e n t u p o n th e p r e s e n t a t i o nof causa lly necessa ry cond i t ions - cond i t ions which m ay go un iden t i f ied .S imi la r ly , the re a re add i t iona l cond i t ions which a re causa l ly necessa ryfor one to see tha t th is is h is chi ld : one s ey es , opt ic nerves , and bra incen te rs mus t be in ce r ta in s ta te s wi th in ce r ta in to le rances ; and beyonds u c h c o n d i t i o n s o f t h e o b s e r v e r , t h e e n v i r o n m e n t m u s t e i t h e r p o s s e s sce r ta in cha rac te r i s ti c s o r a nyw ay lack ce r ta in o the r cha rac te r i s ti c s . Bu tonce aga in , in o rde r to obse rve tha t someth ing i s the case , a pe rsonneed no t adver t to o r use be l ie f s abou t these cond i t ions : i t i s su f f ic ien t


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1 5 0 W I L L I A M S B O A R D M A N

t h a t t h e c a u s a l c o n d i t i o n s b e sa t i s f ied ; the pe rson need no t k n o w t h a tt h e y a r e .

Th u s , a l t h o u g h s o m e p e r c e p tu a l j u d g m e n t s m a y b e r e c o n s t r u c t e dfa i r ly accura te ly a s in fe rences , no t a l l can be so recons t ruc ted . Fo rone th ing , the use o f exp l ic i t in fe rences p resuppo ses the ab i l ity to m ak eo t h e r j u d g m e n t s n o n - in f e r e n t ia l l y . Th i s u l t im a te d e p e n d e n c y o f r u le -f o l lo w in g ju d g m e n t s u p o n in tu it i v e j u d g m e n t s is a t t h e b o t to m o f t h ecom mo n-sen se v iew tha t in fe rences re s t upo n obse rva t ion : i f one can-no t , e .g . , s imply s e e what the da ta a re , then he wi l l no t be ab le to in fe rth in g s f r o m th e m . A n d f o r a n o th e r , w e m a y b e f a r m o r e c o n f id e n ta b o u t a p e r c e p tu a l j u d g m e n t s r e l ia b i li t y t h a n a b o u t a n y i d e n t if i c at i o nof i ts impl ic i t da ta . Jus t a s in fe rences a re l i able to go wrong , so one sexe rc i se o f pe rcep tua l ab i l i t i e s i s f a l l ib le . To be su re , somet imes wha tm a k e s a p e r c e p tu a l j u d g m e n t g o w r o n g m y b e a n a lo g o u s t o t h ec o r r e s p o n d in g f l a w in a n i n f e r e n c e : a b a c k g r o u n d b e l i e f m a y h a v eb e e n f a l s e, o r s o m e o f t h e c ru c ia l c u e s m a y h a v e b e e n o b s c u r e d , o rs o m e t im e s o n e m a y h a v e b e e n i n c a u t io u s o r h a s ty . Bu t s o m e t im e s ,un l ike ins tances o f in fe rences , no one can say why , on tha t pa r t icu la roccas ion , a pe rson s ab i l i ty to recogn ize th ings such as th i s fa i led h im.

We a r e n o w in a p o s i t i o n t o u n d e r s t a n d w h y , a s A u s t in p o in t s o u tin h i s O th e r M in d s , c h a l le n g e s a n d q u e s t i o n s p e r t a in in g t o a p e r c e p tu a lc l aim o f r e c o g n i t i o n f o ll o w a d i f f e r e n t p a t t e r n f r o m o n e s p e r t a in in g t oan in fe rence . I f one wan ts to cha l lenge o r gauge the c red ib i l i ty o f anin f e r e n c e , h e n e e d s t o l o o k a t t h e d a t a u s e d a n d a t t h e g r o u n d s w h ic hr e l a t e d t h e m to t h e s o r t o f co n c lus io ns d r a w n . Bu t i f o n e w a n t s t oc h a l l e n g e o r s c r ut i n iz e a p e r c e p tu a l j u d g m e n t o f r e c o g n i ti o n , o n e l i k elyhas no exp l ic i t r eco rd to cons ide r . A nd s ince the re l iab i li ty o f thep e r c e p tu a l j u d g m e n t m a y o u t s t r ip t h a t o f a n y i n f er e n c e s u g g e s te d a s i tsr e p l i c at i o n , e x a m in in g a r e p l i c a ti o n m a y n o t b e a n a c c u r a te w a y o f

e v a lu a t i ng t h e c r e d ib il i ty o f t h e p e r c e p tu a l j u d g m e n t . I n s t e a d , o n e m u s tlo o k to t h e p a s t p e r f o r m a n c e s o f t h e p e r c e iv e r - t o s e e w h e th e r i t i sl ike ly tha t he has dev e loped the ab i l i ty wh ich he c la ims to hav e usedon th i s occas ion , and to see whe the r th i s occas ion was the so r t to havepermi t ted i t s r e l iab le exe rc i se . ( In a c lose ly ana logous way , when wew a n t t o d e t e r m in e w h e th e r J o n e s t e n n is p l a yin g o n t h i s o c c a sio n w ass k il lf u l o r m e r e ly l u c k y , w e lo o k to w h e th e r h e h a s h a d t h e o p p o r tu n i tyto d e v e lo p s u c h sk il l a n d w h e th e r t h e p r e s e n t c i r c u m s ta n c es w e r e p r o p i-t ious for i ts exerc ise ; we do n o t dem an d tha t Jone s c i te a se t o f exp l ic i tru le s fo r p lay ing tenn is , s ince tha t wi l l no t in genera l be a re l iab le


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R E L T I V I T Y O F P E R C E P T U L K N O W L E D G E 151indicator of what we wish to assess.) After all, when we question aperson who claims perceptual knowledge, we want to find out whetherthe person probably did see what he supposed he recognized, notwhether he would have been able to infer what he saw from someexplicit set of data.

Thus we find Austin s insistence on the distinction between recogniz-ing and inferring to be fully justified. As a result, Austin is supportedin his further claim that certain sorts of facts about the perceiver andabout the thing perceived need not be substantiated by the perceiverin order for it to be correctly asserted that he has seen what he supposedhimself to have seen. Although these items would be part of the data ofan inference which emulates the perceptual judgment, the perceiver sgrounds for believing them are not relevant to whether he saw what hesaid he saw: he did not claim to have inferred, but to have recognizedThus, the distinction between recognizing and inferring forestalls onetraditional entrance of the problem of skepticism. For Jf seeing reallywere the making of an inference, then the observer would certainlyhave to include in his grounds for his perceptual judgment some detailsconcerning these cues ; and he would also need to have subsidiaryevidence tending to substantiate such details. And since one scarcelyever has relevant and conclusive evidence about such things, traditionalskeptical problems would consequently assert themselves and force thedenial that one ever really does see such a thing as that X was at theparty. But since recognizing is not the making of an inference, thesedetails are not data which the observer needs to have adverted to andmade sure of; instead, they are causal conditions which simply musthave been satisfied - independently of what the observer knew orreasonably believed. Indeed, the observer can make an inference whichgoes quite in the opposite direction: realizing that he has seen X at theparty, and realizing that doing so required a host of causal conditionsto have been satisfied, he is able to infer that these conditions musthave been satisfied.

.We shall be able to appreciate the special features of perceptual recog-nition which explain its differences from inference if we see it as aninstance of the wider category of intuitive judgments - ones which donot bring rules to bear. (While this discussion will try to make the


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52 W I L L I A M S B O A R D M A N

dif ferent k inds of judg me nts c lear by concentra t ing on the e xtrem es offul ly in tu i t ive judgments as contras ted wi th inferent ia l judgments , weneed to rem em ber that the re are many mixed instances . Wh en , fo rexample , one c la ims to have recognized a goldf inch f r om i ts color andits bil l , one is art iculating a general range of characterist ics whichenabled him to ident i fy the b i rd as a goldf inch: l ike the correspondinginstance of inference, if goldfinches have no dist inguishing sort of bil l ,then the claim of recognit ion fails .) To acquire an abil i ty to makeintui t ive judgments , one typica l ly must be t ra ined through apprent ice-ship by someone who has the in tu i t ive abi l i ty a l ready (or must haveacquired the abi l i ty through much exper ience) . The pupi l acquires thein tuit ive abi l ity by having large num bers of specific judgm ents correc tedor conf i rmed by the master ; he subseq uent ly acquires , e .g . , an ear forlanguage, a nose for argum ent , an eye for fashion. Eve n wh en histraining is aided by the use of some explici t rules (as stud ents of Englishare a ided by ru les of gram mar ) , h is eventual abi l ity to mak e re l iablejudgm ents by ear can excee d his capaci ty and that of h is teacher toart iculate explici t , general rules which decide those cases correctly.Ofte n , the de velo pm ent o f a se t of com prehensive , explic it ru les i sdepend en t upon and sub sequen t to the ex i s tence o f som eone s in tu i tiveab i li ty to m ake the re levan t judgments . For example , long be fo re Ar i s -to t le or o ther logic ians, p eople were able to d ist inguish good argumen tsfrom poo r o nes on a case-by-case bas is ; la ter , ru les of logic were devisedto al low a fair ly mechanical and systematic identif ication of valid argu-ments . Such ru les enable someone who has not mastered the in tu i t iveenterpr ise to m ake jud gm ents w hose re l iabi li ty rivals those of the ex-pert . But, often, the set of explici t rules is never as rel iable in the hugevar ie ty of ins tances as is the e xper t s in tu it ive abi l ity . (Not ice h ow anygiven sys tem of formal logic can deal wi th only a fa i r ly narrow type ofval id argum ent - nev er wi th the whole range o f them at once; for theresult ing complexity of rules dealing with all val id arguments would beoverwhe lming.) Thus , even if we could reconstruct s ome intuit iveabil i t ies as the mechanical application of explici t rules, we could notreconstruct a ll . Som e are s imply too complica ted; and, anyw ay, the

use of expl ic i t ru les presupposes the abi l i ty to make other judgmentsintuitively.The special advantage of an intuit ive abil i ty is that i t al lows far-reaching yet re l iable extrapola t ions to be made on the meager bas is ofre la t ive ly few ins tances which have served as the bas is of one s ins truc-


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t i o n . I n f e r e n t i a l j u d g m e n t , o n t h e c o n t r a r y , is fi rm ly t e th e r e d t o t h o s econdi t ions specif ied in i ts expl ic i t ru les . Thus in learn ing to recognizeX in c i rcumstances where he i s wear ing h i s ha t and wa lk ing , one maythe r eby acqu i re the ab i l i ty to recogn ize h im even wh en he i s sea tedand ha t le ss . In con t ras t , i f we have a l is t o f cha rac te ri s t ic s wh ich un-ique ly iden t i fy X and on ly som e bu t n o t a ll o f the i t ems a re sa t i sf ied ,then we c an in fe r ne i th e r tha t i t i s X nor tha t i t i s no t.14

Ho we ver , in tu i t ive ab il i ti e s possess a spec ia l d i sadvan tage : th e re m aybe h idde n l imi ta t ions on the c i rcumstances in wh ich they can be re l iab lyexerc i sed . I f I have lea rn ed to recogn ize go ld f inches whi le in Br i ta in ,I have no t the reby acqu i red the ab i l i ty to recogn ize them in a ra info res t inhab i ted by o the r spec ies o f b i rd re sembl ing the go ld f inch inw a y s f o r w h ic h t h e p o p u la t i o n o f Br i t i s h b i r d s h a s n o t p r e p a r e d m e .Ye t I migh t no t rea l ize tha t ( in th i s d i f fe ren t env i ronment ) I may no tp roper ly iden t i fy the b i rd be fo re me as a go ld f inch (even i f i t happ ensto e a go ld f inch). In con t ras t , i f I were wo rk ing f rom a comple te andexp lic it inven to ry o f the cha rac ter i s t ic s o f go ld f inches , I wou ld - evenin a ra in fo res t - be ab le to iden t i fy the b i rd b e fo re m e as a go ld f inch,suppos ing tha t I a sce r ta ined the inven to ry to be sa t i s f ied . Thus , wh i lethe te the r o f an in tu i t ive ab i l i ty i s mo re e la s t ic than tha t o f an in fe rence ,i t i s l i ab le to b reak wi thou t warn ing .

As a p rac tica l ma t te r , the h idde n l imi ta t ions o f in tu i t ive ab il i ti e sbeco me a d i f f icu l ty wh en , e .g . , one i s ca l led upon to iden t i fy one sassa i lant f rom a pol ice l ine-up: rea l iz ing tha t he has the abi l i ty tod isc r imina te the cu lp r i t f rom a l l the o the r peop le who were in the pa rka t t h e t im e m a y m i s l e a d o n e i n to s u p p o s in g t h a t h e h a s t h e r a th e rd i f fe ren t ab i l i ty to iden t i fy the cu lp r i t f rom som e g roup o f peop ler a n d o m ly c h o s e n f r o m a m u c h l a r g e r p o p u lat i o n . W h a t m a k e s t hi sfami l ia r l imi ta t ion a ph i losoph ica l d i f f icu lty i s tha t one m ay n o t be ab teto te l l when the cu r ren t c i rcumstances a re s ign i f ican t ly o r su f f ic ien tlyun l ike the ones in wh ich he acqu i red h i s ab i l i ty tha t he canno t coun ton i ts re l iab le exerc ise .

Th e l ia b i li ty o f a p e r c e p tu a l j u d g m e n t t o f a i l t o b e k n o M e d g e d o e sno t , by i t se l f , suppor t a tho roughgo ing skep t ica l cha l lenge to see ing asa m e a n s o f k n o w in g . Th a t o n e s o m e t im e s m i s t a k e n ly su p p o s es t h a t h erecogn izes th i s X as Y does no t p rove th a t in d i f fe ren t , more cus tom aryc i rcumstances he mus t fa i l to recogn ize an X as a Y: my subsequen tb i rd wa tch ings , fo r example , migh t be re s t r ic ted to the Br i t i sh env i ron-me n t . Af te r a ll , one s pe rcep tua l ju dgm ent i s an exe rc i se o f a sk i ll


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1 5 4 W I L L I AM S B OAR DMA N

which, like any o ther skill, might be successful only in certain circum-stances - like that of a tennis player who is an expert on clay courtsbut not on grass. Moreover, as Dretske urges, is even if one s ability tosee that X is Y is restricted to a narrow set of circumstances, neverthe-less, its exercise does not require him to know that he is in favorablecircumstances; it suffices that he be in them.The threat of skepticism does arise, however, when we consider afurther point. If we concede that a person s perceptual judgments areliable to error in circumstances which are abnormal or atypical com-pared to the circumstances in which one has acquired the ability tomake that sort of perceptual judgment, then we can argue that someof his perceptual judgments of this sort nevertheless qualify as knowl-edge only if we can distinguish abnormal from normal circumstancesindependently of whether they permit success Only if we can do thatcan we distinguish the fortuitously correct perceptual judgments whichoccur in abnormal circumstances from the knowledge obtained throughperception in the normal circumstances. When the perceptual judgmentthat X is Y is made in abnormal circumstances, it will require supple-mentary knowledge in order for it to qualify as knowledge: this isbecause abnormal circumstances for a perceptual judgment are thosein which the application of one s ability to recognize that X is Y failsto rule out other relevant possibilities to Xs being Y. For example, ifI subsequently try to apply my goldfinch spotting skills while in a rainforest, I shall then need to exclude the possibility that I am seeing abird which, though not belonging to the class of non-goldfinches in theBritish population of birds (the normal circumstances for the exerciseof my skill), nevertheless is not a goldfinch. And again, if my father stwin, whom I have never met, is in town, then despite my confidencethat it is my father whom I see from some distance, and even thoughit is in fact my father, nevertheless, I may not see that it is; for heremy apparent recognition is consistent with its being my father s twinwhom I see. Notice in these examples that the obstacle to my gainingknowledge by recognition is that although I have learned to discriminateYs from a familiar set of non-Ys, I have not learned to discriminatethem from the different set or kind of non-Ys relevant to these unaccus-tomed situations. In these atypical circumstances, I could know that Iwas seeing a goldfinch (or, my father) only if I had supplementaryknowledge eliminating the further alternatives.Thus to meet the general skeptical challenge, one must be able to


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d is t ingu ish , in a way which i s no t a rb i t ra ry , those c i rcumstances in wh icha p e r c e p tu a l j u d g m e n t n e e d s t o b e a c c o m p a n ie d b y s u p p le m e n ta r yin fo r ma t ion e l imina t ing re levan t a l te rna t ive poss ib il i ti e s f rom th ose c i r-cumstances in wh ich a pe rcep tua l judgment requ i res no such supp lenm e n ta t i o n in o r d e r t o b e k n o w le d g e . A n d s o , i t is r e q u i r e d t h a t r e l e v a n tpossibili t ies not a r i se in eve ry c i rcumstance : on ly facts of the s i tua t ioncan ra i se re levan t a l te rna t ive poss ib i l i t i e s wh ich need to be e l imina tedin o r d e r f o r o n e t o see tha t X i s I1 . In pa r t icu la r , a s bo th Aus t in andDre tske ins is t , the m ere conce ivab i l i ty o f a l te rna t ive poss ib i li t ie s mus tn o t n e c e s s i t a t e s u p p le m e n ta r y i n f o r m a t io n . Th u s , f o r e x a m p le , t h o u g hi t is logica l ly poss ib le th a t the pers on I see is a c lone of my fa ther ,s e c r e tl y c o n t r i v e d b y in v a d in g M a r t i a n s , n e v e r th e l e s s , I n e e d n o t k n o wtha t th i s poss ib i l i ty i s no t rea l ized in o rde r to recogn ize h im as myfa the r .

Al though i t i s t empt ing to fa l l in wi th th i s in s i s tence tha t we d i s t in -gu ish be tween c i rcumstances where rea l poss ib i l i t i e s a r i se and thosew h e r e t h e y d o n o t , n e i t h e r A u s t in n o r D r e t s k e s h o w s h o w to d r a w s u cha d is t inc t ion with ou t begging crucia l quest ions . Th e d if f icul ty is to se t t Ie ,w i th o u t b e in g a r b i t r a r y o r ad hoc, ju s t wha t k inds o f fac t s and wha tse lec t ion o f them do c rea te a ' r ea l ' o r ' r e levan t ' poss ib i l i ty , one whichmarks the c i rcumstances a s abnormal o r a typ ica l . Fo r wha t a t f i r s tappears to be a mer e conce ivab i l i ty can o f ten be re s ta ted so tha t i tseems to be a 'genu ine ' possib i li ty , ac tua l ly rea l izab le , in Dre tske ' swords , in the nu ts and bo l t s o f the pa r t icu la r sys tem in que s t ion . ~6A nd , a s a re su l t , i t is di f ficu lt to sho w tha t an , c i rcumstance i s no ta b n o r m a l .

Suppose i t to be a fac t tha t a l though my fa the r has no twin , he hasl iv ing in Timbuk tu a Doppelgiinger - a look-a l ike~ Then does tha t factc rea te a ' r ea l ' poss ib il i ty tha t i t is m y fa the r ' s do ub le w hom I am see ingn o w ( as I l o o k d o w n th e s t r e e t i n A p p le to n , Wis c o n s in ) ? I f th e a c tu a lexis tence of a look-a l ike crea tes a ' rea l ' poss ib i l i ty tha t I might bemis taken in my jud gm ent tha t I see m y fa the r , the n , s ince I possess nosupp lemen ta ry in fo rmat ion exc lud ing tha t poss ib i l i ty , we sha l l have tosay tha t I do not s e e t h a t i t is m y f a th e r a p p r o a c h in g - e v e n t h o u g h i tis him, h is Doppelgiinger cur ren t ly be ing in Timbuk tu . Us ing th i s pa t -te rn o f iden t i fy ing ' r ea l ' poss ib i l it i es , we cou ld ra i se skep t ica l cha l lengesvir tua l ly in every case whe re s om eo ne c la ims to see tha t X is 17. Fo rexample , i t i s sure ly a fact t h a t s o m e H o l l y w o o d m a k e - u p a rt is t h a s t h eab i l i ty to d i sgu ise somebody so tha t I wou ld mis take h im (a t th i s d i s -


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56 W I L L I AM S B O A R D M A N

tance) for my father; whether such a person has had the opportunity anddesire to deceive me is a matter about which I have no supplementaryknowledge Indeed, the recent facts of biological discovery might evenmake it actually possible that with great sums of money and patiencea team of scientists could clone a genetic copy of my father. Theproblem is that there are always numerous subsets of facts which, bythemselves - in the absence of further facts - would serve as relevantevidence that one is mistaken. 17 If the existence of such a subset o ffacts is sufficient to raise 'relevant' alternative possibilities, then theclaim to knowledge of every perceptual judgment unal loyed with supple-mentary knowledge of the further facts would be compromised. But,clearly, the same considerations would prevent one from knowing anysubset of facts, since there would always be still further facts that onewould need to know first.On the other hand, we might insist upon including such further factsalong with the subclasses as defining the circumstances which in factprevailed on this occasion . 18 Thus, for example, even though myfather's Doppelgdnger exists, it is a further fact that he is currently inTimbuktu and so not available for my inspection. Accordingly, wemight say that my mistaking my father's look-alike for him was not a'genuine' possibility under 'the prevailing circumstances'. But now theproblem is that since 'the prevailing circumstances' include all of thefacts which prevented or were inconsistent with the realization of alter-native possibilities, this option would serve as a pattern for makingevery perceptual judgment which happens to be correct an instance ofknowledge: returning to the example where my father 's twin is in town,it is a further fact that the twin is currently in another part of town andso not available to my scrutiny (and so, my having mistaken him formy father would not be a genuinely alternative possibility under 'theprevailing circumstances'); and when I see the goldfinch in the rainforest, it is a further fact that no spurious goldfinches are on the treeto which my eyes are turned. In general, whenever an alternativepossibility is not realized, there will always be facts which either pre-vented or were inconsistent with its realization. Nor is there any non-arbitrary way to single out the truly relevant facts of the prevailingcircumstances (my father's twin is in town; my father's Doppelgdngeris not) from those which are not truly relevant (my father's twin is inanother part of town; the spurious goldfinches are on other trees).Thus, it seems futile to search for a principled, non-arbitrary way to


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distinguish 'abnormal' from 'normal' circumstances. The problems 19 forthis sort of account are much deeper than Dretske allows when he (quiteproperly) acknowledges flexibility and plasticity in the notion of

r e l e v a n t alternative possibilities . 2.

What is required to block the general skeptical challenge to perceptualknowledge is something more radical than a distinction between thecustomary circumstances of perceptual judgment and atypical ones.Surely Austin is correct in arguing that while it is the purpose of aclaim of knowledge of p to exclude some specific ways of being mistakenabout p, no knowledge claim is intended to exclude all conce ivab leways of being mistaken. And so the host of skeptical challenges to aclaim of knowledge is often frivolous: as Austin says, Enough isenough .21 What refutes a person's claim to know that p is a showingthat 'p' is probably false or that there is some concrete reason tosuppose that [he] may be mistaken in this case ; 22 the inherent liabilityof a human to mistake does not prevent one f rom knowing things. Butif a person's knowing that p does not require him to be able to meetevery conceivable challenge, then we ought to be able to specify whichchallenges he must be able to meet in order (to be correctly said) toknow that p. In other words, if 'enough is enough', how do we deter-mine what is enough? I suggest that when a person claims knowledge,he does so in a context where some specific difficulties in supposingthat p have been raised explicitly or implicitly: it is these difficultieswhich both make a claim of knowledge appropriate and also determinewhat counts as 'enough' to be correctly said in this context to knowthat p.

Warnock has attacked philosophers who use, as I do, the notion ofa c la im of knowledge as a central element in their accounts of knowing;he accuses such philosophers of greatly exaggerating the importance ofclaims to know. 23 To escape Warnock 's criticisms, we may distinguishroughly between two sorts of circumstances in which we speak of some-one's knowing that p or seeing that X is y.24 In what we may stylea b iographical context, the question motivating the discussion is theexplanation or moral appraisal of a person's conduct. In this type ofcontext, the interrogators have already discovered the truth of 'p' orthat X is Y; what they want to determine is why the person acted the


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58 WI LLI AM S BOARDM AN

way he did - and whether he was, at the time he acted, in a reasonableposition to act in accordance with p s being true. Suppose that aparticular bridge was in danger of imminent collapse, and yet a super-visor sends a workman across it to fetch a tool; then the questionwhether the supervisor is to blame for the workman s subsequent deathor injury will focus on whether the supervisor knew or could see thatthe bridge was unsafe. If, for instance, the supervisor had merely beenaware of various rumors regarding the bridge s lack of safety but wasreasonable in dismissing them, then he would not be to blame forthe tragedy. In biogr phic l circumstances, we distinguish between aperson s knowing that the bridge was unsafe, and his having been inignor nce of the bridge s lack of safety. The distinction between heknew and he ought to have known is not very interesting in this typeof circumstance, since either makes him blameworthy; indeed, it isworth noting that lawyers frequent ly alternate the two expressions indif-ferently . Even the distinction between he knew and he believed isnot very interesting: for his inability to have claimed to know that thebridge was in imminent danger would not serve as an excuse or explana-tion so long as he h d supposed that the bridge was in imminent dangerof collapse. Again, when we are explaining or predicting a person sacts, the distinctions are t rea ted in the same way: the general who fearsthat the enemy knows of the planned invasion on Tuesday would not(and should not) be mollified by a showing that the enemy generalscould not be entitled to claim knowledge of the plans - since they haveonly guessed at them; it is sufficient corroboration of his fears if theyare prepared to act in accordance with the proposition our enemy isplanning an invasion on Tuesday . I t is in these biogr phic l circum-stances where one confesses and admits to having known, rather thanclaims to have knownYBut there is another sort of context where the interrogators have notalready discovered whether p is true, and where the question motivat-ing the discussion is whether p may be accepted as established orcertified. In what we may call certific tion circumstances, to talk ofknowing or having recognized or having seen that p is to make orendorse a claim that p - to advance p as established, in contrast to itsbeing highly probable (though less than conclusive), a reasonable bet,or only a guess. Here the tru th of p is being claimed together withthe person s being in a special position to make the strongest sort of


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claim. It is with certification circumstances that epistemological dis-cussions, including the present one, are chiefly concerned.

Without a special context, the question 'Do you know that X is )1.9'is incomplete. Apart from artificial examples coined by philosophers,the question would be asked only in circumstances where a problemwith the supposition that X is Y or with the speaker's possession ofthat information was explicitly stated or contextually apparent: 'Giventhat this is too early in the spring for goldfinches, how do you know itwas a goldfinch?'. 'Given that your father's twin is in town, how doyou know it was your father?'. Again, the questioner might make itclear that he had heard the prevalent rumors bruiting that p, and askwhether the person knows that p: in such a case the gravamen is thatthe assertion of p is merely an unsubstantiated rumor.Accordingly, statements of the form 'I know that p' , 'I saw that p',and 'He recognized X as being Y', should normally be viewed asresponses to specific sorts o f worries. 26 Apar t from such suggestions ofa specific sort of worry', a declaration of knowledge is vacuous, thoughit may be made substantive by our presupposing some sort of worry asunderstood by the speaker. In this respect, Aust in was perfect ly correctin noting the similarity of a declaration of knowledge to a guarantee: 27a guarantee is not made absolutely, but against contingencies of poorworkmanship, poor design, liability to misuse by the clumsy, liabilityto the ravages of long and hard use. One can guarantee that a productwilt continue to work during the worst sort of electrical storm or after atypically savage attack by a four-year-old, but one cannot meaningfullysimply guarantee a product unless some range of usual, customarydefects or liabilities is understood. No doubt the relativity of guaranteescan escape notice because their audience is usually acquainted with thesorts of liabilities to which a particular kind of product is subject, andso has some idea which of those liabilities one could reasonably expecta manufacturer to minimize or extinguish. In a parallel way, when aspeaker is prepared to urge the truth of 'p', the context usually makesclear to him what his hearers consider to be the obstacle(s) to acceptingp as true. Thus, as Ebersote points out , 2s in the absence of a specialcontext, it is outrageous for one to say that he knows this or that. Itisn't that his statement would be false; rather, it would be empty -merely an emphatic way of saying 'p'.

What makes it appropriate, then, for someone to say that he knows


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160 W I LLI A M S BO A RD M A Ntha t X i s Y i s the dou b t rega rd ing Xs be ing Y which has been expressedo r s u g g e s t e d . An d wh e n , in those circumstances, a pe rson says tha t heknow s o r sees tha t p , he i s say ing tha t he can respon d de f in it ive ly tothat dou b t a s be ing g round less o r can ce r t i fy p no tw i ths tand ing i t.Th u s , s u p p o s e t h a t t h e wo r r y a b o u t wh e th e r i t i s m y f a th e r wh o i sr ing ing the doorbe l l i s tha t h i s schedu le would p reven t i t s be ing h im.Th e n p e r h a p s I a m a b l e to c o u n te r t h e d o u b t w i th t h e i n f o r m a t io n t h a th e h a d t o ld m e e a r l ie r t h a t h e w o u ld t a k e a b r e a k t o v i si t t h is m o r n in g .Or p e r h a p s I h a v e r e c o g n iz e d h im a s h e wa lk e d to wa r d t h e f r o n twindow. Ei the r o f these rep l ie s de fends the a sse r t ion , tha t i t i s myfa the r , aga ins t the sugges ted reason fo r doub t ; in e i the r case I mayp r o p e r ly c l a im k n o wle d g e . Bu t i f , o n t h e o th e r h a n d , t h e wo r r y i s t h a ti t migh t be my fa the r s twin o r Doppelgiinger w h o h a s c o m e t o m e e tme , then I sha l l no t be ab le to d i smiss that doub t by say ing tha t Irecogn ize h im as my fa the r .

Thu s to say I kno w tha t p o r I see tha t p i s no t to g ive an abso lu tegua ran te e th a t p : one i s s ta t ing tha t he is in a pos i t ion relative to specificworries t o s e t t l e d ef in it e ly t h e q u e s t i o n wh e th e r p . He m a y b e p l a c e din such a pos i t ion by va r ious so r t s o f c i rcumstances : he may havec o n c lu s iv e e v id e n c e ; h e m a y h a v e r e c o g n iz e d t h e f a c t ; h e m a y h a v er e c e iv e d a s s u r a n c e s f r o m s o m e o n e e l s e wh o knew 29 Th e a p p r o p r i a t e -n e s s a n d s u c c e s s o f h i s g r o u n d s w i l l d e p e n d b o th u p o n th e n a tu r e o fthe wor r ie s which were ra i sed and on the c i rcumstances in which hewas p laced re la t ive to p . Bu t in any case , whe the r such a wor ry needsto be taken se r ious ly (and so i s sues in I know tha t p o r I see tha t po r , i n s t e a d , I wo u ld b e t t h a t p ) w i ll d e p e n d u p o n wh e th e r t h e r e a r eg rounds in the cu r ren t c i rcumstances which sugges t the l ike l ihood o fth e wo r r y s b ein g t r u e . I m a g in e t h a t u p o n m y lo o k in g o u t th e w in d o wa n d a n n o u n c in g t o m y wi f e t h a t m y f a th e r i s c o m in g u p t h e p a th , s h erepl ies whimsica l ly , Per hap s i t i s only a Doppelgdnger : a l though Ic a n n o t t h e n g iv e t h e a s s u r a n c e t h a t I r ec o g n ize m y f a th e r , n e i t h e r m u s tI c o n c e d e r e a s o n a b le d o u b t . A d o u b t a b o u t wh e th e r p d o e s n o t p r o p e r lya r is e u p o n a wh im s y . I t is o th e r w i s e i f we h a v e r e c e n t ly h e a r d r e p o r t sf r o m o u r n e ig h b o r s o f t h e i r b e in g a s to n i s h e d b y a l o o k - a l i k e t o m yf a th e r : t h e n t h e wo r r y is l eg i t ima te , and I mus t admi t tha t I do no t (a tthis d is tance , anyway) see tha t i t i s my fa the r .Ho w e v e r , a c la im o f k n o wle d g e i s u n l ik e a g u a r a n t e e , i n t h a t b e y o n done s be ing en t i t l ed to c la im to know tha t p und er the c i rcumstances ,p m u s t a c tu a l ly b e t r u e i n o r d e r f o r o n e t o k n o w th a t p . W h e n a


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product fails in precisely the circumstances in which the manufacturerguaranteed it, it is nonetheless true that the manufacturer did guaranteethe product; but when a person claims to know that p in circumstanceswhere he is able to defend the assertion of p against specific contextualworries, if it nevertheless transpires that p is false, then the persondid no t know that p.30 Imagine, then, that in circumstances about whichmy wife and I have been kept ignorant (e.g., my father has carefullyplanned a surprise meeting of his twin brother and my family), myfather s twin approaches my house and hears this dialogue between meand my wife: Put on the kett le, would you? My father is here . Itcan t be your father - he s still at work: remember , he s on the morningshift this mon th . I know it s him - I see him . In such circumstances,my uncle is in a position to be amused by my false claim of knowledge.One s being warranted under the circumstances in claiming to knowthat p is only a necessary condition of one s actually knowing it.On the othe r hand, imagine that in the same circumstances - asbefore, my father has planned the surprise meeting - it is in fact nayfather who approaches the house, his twin brother remaining unseenin the car parked by the curb. In this case, the claim of knowledgeexpressed to my wife is true: here I am in a position to surmount mywife s objections to my identification of the visitor as my father; and,moreover, it is my father. The further fact of my father s twin beingnearby is irrelevant to whether I know what I claim to know, as areadditional facts such as that my father has a o p p e l g a n g e r (residing inTimbuktu), who, were he approaching the house, would be mistakenby me for my father.

One is probably unsatisfied at first glance with these protestations ofirrelevancy. But that is due, I think, to a confusion between two setsof contexts: there is, first, the context in which the person in theexample assures his wife (against the worry that the father s workschedule prevents his being the visitor) that he sees that the visitor ishis father; but there is the f u r t h e r circumstance of the reader who,looking at the example from a God s-eye view, has information whichthe wife in the example does not - that the father s twin is in thevicinity. If the reader imagines himself in the example and investedwith this further information, then he may imagine that the relevantcontext contains the additional worry - that the visitor might be hisfather s twin; and, as I have said earlier, if that worry wer e properlyraised, the husband could not reasonably claim to know that the visitor


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i s h i s fa the r . Y e t , on the con t ra ry , the a dd i t iona l in fo rm at ion possessedb y th e r e a d e r d o e s n o t d e f ine t h e c o n t e x t i n w h ic h th e c l a im o f k n o w l-e d g e s h o u ld b e j u d g e d . I n e f f e ct , t h e p e r s o n i n th e e x a m p le i s im a g in e da s b e in g q u e r i e d i n tw o s e p a r a t e w a y s : G iv e n t h a t y o u r f a th e r iss u p p o s e d t o b e o n h i s m o r n in g s h i f t , c a n y o u b e s u r e t h a t i t i s h im ?and Gi ven tha t yo ur fa the r s twin is in the v ic in i ty , can yo u be su retha t th i s is you r fa the r ? . A leg i t ima te fo rm o f th is so r t o f supp lem en t ingo f c o n t e x t o c c u r s i n a c o u r t o f l a w w h e n n e w in f o r m a t io n c o m e s t ol igh t o f wh ich an eyewi tness had been ignoran t : to the ques t ion nowp u t t o h im , Ca n y o u ( n o w ) b e s u r e th a t i t w a s y o u r f a th e r w h o m y o usaw ( in l igh t o f the cu r ren t ly d i sc losed fac t tha t your unc le was in then e ig h b o r - h o o d ) ? , t h e p e r s o n m u s t r e p ly t h a t h e might b e m i s t a k e n i nsuppos ing tha t i t was h is fa the r who m he saw, even th oug h he o r ig ina l lye n t e r t a in e d n o s u c h q u a lm s . H e m u s t n o w t e s ti f y t h a t h e thinks he sawh i s f a th e r , n o t t h a t h e r e c o g n iz e d h im ; h e c a n n o t e n d o r s e h i s e a r l i e rc la im to know tha t i t was h i s fa the r .

P o t e n t i a l c o n f u s io n b e tw e e n d i s t i n c t s e t s o f c o n t e x t s i s a b e t t e d b ythe sub t le l ingu is t ic complex i t ie s o f the re la t ionsh ips be tween p resen tand pas t t enses o f the ve rb kno w , an d be tw een f i r s t -person c la ims tok n o w a n d in d i r e c t r e p o r ts o f s u c h c la im s . Wh e n o n e s a y s I k n e w o rh e k n e w o r h e k n o w s , o n e i s n o t m e r e ly r e p o r t in g t h a t X w a s o r is

in a pos i t ion to c la im kn owle dge ; one i s endors ing i t a s one s o wnc u r r e n t c la im . Wh e n I sa y I k n e w th a t p , I t h e r e b y c l aim to k n o w th a tp n o w ; a n d w h e n I s a y H e k n e w th a t p , o n c e a g a in I c l aim to k n o wtha t p . Bu t i f the cu r ren t c i rcumstances invo lve a fu r the r wor ry -concern ing w he th e r p - wh ich d id no t a r i se in the c on tex t in wh ich thee a r l ie r c l aim o c c u r r e d , o n e c a n n o t e n d o r s e t h a t c l a im ( o n e c a n n o t s a y ,X k n e w th a t p ) w i th o u t t h e r e b y im p ly ing th a t X w a s i n a p o si t io n t o

o v e r c o m e th i s f u r th e r w o r r y . Th u s , w h e n th e c o n t e x t h a s c h a n g e d , Ik n e w d o e s n o t w o r k s im p ly a s t h e p a s t t e n s e o f I k n o w , a n d h e k n e wd o e s n o t m e r e ly r e p o r t t h e t r u th o f another person s ea r l ie r c la im, Ik n o w . F o r t h a t r e a s o n , a p e r s o n p o s s es s in g t h e a d d i t i o n a l i n f o r m a t io nth a t t h e f a th e r s tw in w a s i n t h e v i c in it y m a y n o t s a y t h a t t h e h u s b a n dknew tha t the v i s i to r was h i s fa the r : fo r tha t wou ld fa l se ly imply tha tt h e h u s b a n d h a d b e e n i n a p o s i ti o n t o o v e r c o m e th e p o t e n t i a l o b je c t i o nto h i s iden t i f ica t ion , H ow can you be su re tha t i t is no t yo ur fa the r stw in ? . N e v e r th e l e ss , t h e h u s b a n d s c l a im was a p p r o p r i a t e a n d true T od e n y th is w o u ld b e t o p lu n g e im m e d ia t e ly i n to t h e p r o b l e m s w h ic h w esurveyed a t the c lose o f Sec t ion 2 above : i t wou ld be to demand


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R E L T I V I T Y O F P E R C E P T U L K N O W L E D G E 163supplementary knowledge excluding every mistake whose possibility issupported by some subset of facts. For it is not only the fact of thetwin s visit of which the husband is ignorant; he is also ignorant of the

opp e l g i i n g e r who resides in Timbuktu, of the Hollywood make-upartist, and of numerous other facts which - were he to know t h e mselectively without knowing further facts inconsistent with the alterna-tive possibilities t h e y raise - would prevent him from ever being entitledto claim knowledge.

When we consider the context in which someone claims to knowsomething, we are frequently in possession of new information whichwas not available in the original circumstances. This new informationraises alternative possibilities to p s being the case which w e shouldwant to exclude before we might now claim to know that p. But ourconsequent inability to endorse a claim to know that p which was madein the original circumstances does not show that that claim was false.It merely shows that we do not now stand in the shoes of the originalclaimant.

Perhaps it will help to notice that this peculiarity of endorsement isnot confined to knowledge claims. When we consider a person wholives in different social and cultural circumstances from our own, wemay find ourselves unable to endorse his view of his duties and obliga-tions, since they are condi tioned by institutional rules inconsistent withour own; and yet we sometimes want to admit not only that such aperson did what reasonably s e e m e d right to him but that it was rightfor him then and there. Yet frequently we cannot directly say that whathe did was right, since doing so endorses his judgment from the socialcontext in which we stand. Thus we find difficulties about how to phraseour claim that his judgment that he had a duty to resort to infanticideor sacrifice to the gods was correct in his circumstances. Nevertheless,such difficulties ought not to lead us to imagine that one s moral dutiesare absolute, independent of the institutional framework of the societyin which one lives. Similarly, the obstacles to endorsing one s earl ierclaim of knowledge or someone else s claim of knowledge ought not tomake us imagine that true claims of knowledge are absolute, indepen-dent of the context in which they are put forth.

But will this conception of claims of knowledge as relative to theircontexts help to turn aside the skeptical attacks with which Austin andDretske were concerned when they tried to distinguish between thenormal and abnormal circumstances of perception? Imagine that having


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164 W I LLI A M S BO A RD M A Nl ea rne d to recogn ize go ld f inches in a Br i ti sh env i r onm ent , I subse -quen t ly t ry to app ly m y sk il ls wh i le v is i ting a ra in fo res t . La te r , I r epor tto f r iends tha t a go ld f inch was ac tua l ly ea t ing a banan a . Bu t , t heyq u e r y , a r e y o u s u r e i t wa s n t a r o b in ? W e v e h e a r d o f ro b in s e a ti n gb a n a n a s , b u t n e v e r goldfinches . Ag a in s t t h e s u g g e s t i o n t h a t t h e b i r dm ig h t h a v e b e e n a robin , my Br i t i sh t ra in ing s tands me in good s tead ,for I have l ea rne d to d i s t ingu ish go ld f inches f rom rob ins. A nd so I canprope r ly (and t ru ly - i f i t was inde ed a go ld finch) c la im to have recog-n ized i t a s a go ld f inch . Bu t suppose , in s tead , tha t one o f my f r iends ,who i s more soph is t ica ted abou t the inhab i tan ts o f the ra in fo res t , a sksm e w h e th e r i t m ig h tn t h a v e b e e n a s p u r io us g o ldf in ch ( wh o s e La t inn a m e h e p r o n o u n c e s t o m e ) : n o w I m u s t r e p ly t h a t I a m n o t s u r e , t h a tI hav en t l ea r ned to d i s t ingu ish those so r ts o f b irds . O r p e rhaps i f headds tha t these spur ious go ld f inches have red wing ba rs , I sha l l haveno t ic ed the b i rd s wing a nd wi l l now be ab le to kn ow tha t i t was ag o ld f in c h . Ag a in , c h a n g in g th e e x a m p le , s u p p o s e t h a t h a v in g b e e nmu gge d in a pa rk , a pe rson n ow surveys suspec ts in a l ine -up . I f heiden t if ie s nu m ber th r ee a s the cu lp r it , he is c la iming som eth in g l iketh i s : to see tha t i t i s number th ree as opposed to the others in theline-up. While he i s no t m ere ly c la iming a s imi la r i ty be tw een the cu lp r i ta n d n u m b e r t h r e e ( n u m b e r t h r e e m ig h t b e t h e m e m b e r o f t h e l in e-up m os t re sem bl ing the cu lp r i t wi th ou t the v ic t im s suppos ing tha t heis the cu lp r it ) , nev er the less , h i s c la im is - i f the p res en t accou n t becor rec t - m ore limited than an abs o lu te c la im o f iden t i f ica t ion . I f a newworry is posed - tha t the cu lp r i t migh t ac tua l ly be so me one absen t f romthe l ine -up who looks very much l ike n u m b e r t h r e e - t h e n I d o n trea l ly see how the ea r l ie r l ine -up iden t i f ica t ion cou ld reasonab ly beexpec ted to ru le tha t ou t . The wi tness mus t rep ly tha t th i s i s possible:subsequen t inves t iga t ion mus t cen te r on how l ike ly th i s poss ib i l i ty i s .I f a t h o r o u g h in v e s t i g a t i o n f i n d s n o e v id e n c e o f t h e r e h a v in g b e e ns o m e o n e e l se i n t h e v i c in i ty a t t h e t im e w h o lo o k e d m u c h l i k e n u m b e rth r e e , t h e n t h e w i tn es s m a y p r o p e r ly c l aim to h a v e r e c o g n iz e d n u m b e rth ree a s the cu lp r it . Bu t , o n the o the r ha nd , i f the ev idence sugges t sth a t s o m e o n e wh o lo o k s l i k e n u m b e r t h r e e was in the v ic in i ty a tthe t ime in ques t ion , then the wi tness mus t re t rac t h i s ea r l ie r c la im.S u b s e q u e n t ly , t h e w i tn e ss m a y h a v e a n o p p o r tu n i ty t o l o o k a t t h is n e wsuspec t : on th i s occas ion , he may be ab le to see tha t the new suspec ti s no t the cu lp r i t - pe rhaps the new suspec t has a p rominen t molewhich the wi tness wou ld ce r ta in ly have no t iced had the cu lp r i t been so


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R E L T IV IT Y O F P E R C E P T U L K N O W L E D G E 165endo wed , o r pe rhaps the wi tness s imply sees tha t thi s new suspec t i s no tthe culpr i t . Such supplementary informat ion would a l low the wi tness tore ins ta te h is or ig inal c la im to have recognized num ber three as theculprit.

W hen we turn to on e s eyew itness ident if ica tion o f one s ow n fa theror child or close fr iend, the identif ication is typically much strongerthan that of a recent mugger s imply because one has spent so muchtime and e ffort learning to dist inguish on e s relat ives or fr iends from alarge var ie ty of people . Yet even here i t would be a mis take to imaginethat such an identification might be a bsolute ; ev en this kind o f identif i-ca t ion depends upon the worr ies which are ra ised in the context . Aparent might , in one context , recognize perfec t ly wel l the f i rs t -born ofhis twin chi ldren; ye t when a new worry ar ises tha t the second-bornmight recent ly have undergone plas t ic surgery to d isguise those subt lefea tures w hich formerly dis t inguished him fro m his twin, then the parentwill not have recognized him as his f irst-born (even though i t turns outthat the twin has not had such surgery) . So whether the parent hasactually recognized his f irst-born or has only correctly guessed his ident-i ty wi l l depend upon which worr ies had been ra ised in the context .

Per hap s i t will be tho ugh t th at in arguing for a concep tion of claimsof knowledge as re la t ive I am in ef fec t g iving up any useful not ion ofknowledge, much as do repl ies to skept ic ism which construe knowledgeas highly probable bel ief . I submit tha t the present account does notdo th is . Like Aust in , I want to defen d a conce pt ion of know ledge whichunder l ies the ac tual ways we ta lk of knowing outs ide phi losophicaltheories . Know ledge o f som eth ing / s de fin it ive , on my accoun t , thoughit is definitive against specific worries. This does no t cheapen the no t ionof know ledge, thoug h i t does acknow ledge specif ic l imi ts or boun dar ies .For despite acknowledging such l imits, i t recognizes a qualitative difference be tw een know ing o r see ing tha t p and m ere ly be ing conv inced o ftha t p on the bas is o f wha t o ne sees . The im por tance o f con tex t doesno t e rode the d i st inc tion be tw een know ledge and w ar ran ted be l i e f. Themain d i f fe rences be tw een the p resen t accoun t and those o f Aus t in andDretske are mot ivated by pract ica l considera t ions . I contend that thefeatures o f context w hich limi t knowled ge m ust be fac ts of which theperceiver has so me n ot ice or warning, as he has of worr ies ra ised onthe occasion of h is c laim of knowled ge, ra ther than deta ils of theci rcumstances of perce pt ion of which he might have no n ot ice whatever .Fo r i f there are bound ar ies to k now ledge, th en only i f one can ant ic ipate


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166 W I L L I A M S . B O A R D M A Nthem can one s claim of knowledge carry practical weight. Thus, I wouldmodify an account of knowledge such as Dretske s in the following way:a person, K, knows that s is F relative to a contextually specified worryw = K s belief that s is F is caused (or causally sustained) by theinformation that s is F which eliminates or rules ou t worry w. 31

Finally, we may note a further, distinct element in the context towhich knowledge claims are relative: they are relative to a thresholdof conclusiveness which shifts according to what is expressly at stakein the situation. 32 A particular observation or a particular set of evi-dence may entitle me to say to one who wishes to avoid the incon-venience of walking up four flights of stairs for naught that I know Xis in the building - I recent ly noticed him walking up the stairs; andif tha t was in fact X, I do know. Yet if the question is whether X mighthave been the murderer of his fourth floor competitor, then that sameobservation may entitle me to say only that I believe it was X whom Isaw mount ing the stairs; in this different context, I may not know eventhough I have the same reasons for p which permitted me to know inthe former example.Because a claim of knowledge is relative in the ways I have indicated,it cannot always be transposed from one context to another. SupposeI speak, in succession, to someone who doubts that p for one reason,and then to someone who doubts it upon an entirely different ground:my candid (and perhaps true) assurances to the first person that I sawthat p do not settle what should be my candid reply to the second.Thus, no attempt to set forth the conditions of perceptual knowledgewhich assumes them to be independent of the specific contexts in whichclaims of knowledge are made can succeed in account ing for one sknowledge. For many of the things one sees or otherwise knows areknown only relative to specific obstacles or problems or doubts givenin a particular context which occasioned the claim of knowledge.

N O T E S1 Au st in 1962, pp. 115-24).2 Au st in 1961, pp. 44-84).3 Ayer i970 , pp . 127-30).4 Aus t in 1962, pp . I1 2-24 and pp . 137-42) .5 Aust in 1961, pp. 47-54).


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R E L A T I V I T Y O F P E R C E P T U A L K N O W L E D G E 676 Dretske (1969, pp. 93-112).7 Harman (1973 , pp . 175-76 and 183-86) .8 Pi tcher (1971, pp. 97-112).9 Potlock (1974, pp. 60-64) .

lo Au st in (1961, p. 53) . I t may be that per ceptu al and perce ptual- l ike skil ls are som etime seven fur th er f rom the reach of in fe rence : in d i scuss ing recen t research on cover t aware-ness . Alan Cowey wr i tes tha t a s tudy by Goodale and o thers

demons t ra tes wi th a r res t ing c la r i ty tha t no t a l l complex computa t ions involved inthe neura l repre sen ta t ion of shape , s ize and or ien ta t ion a re access ib le to consc iousjudgments of these object qual i t ies . I t is as i f conscious awareness operated on aneed- to-know bas i s , and tha t m any neura l events such as those govern ing prehen s ioncan occur wi thout awareness in para l le l wi th o thers o f a s imi la r na ture tha t l ead toconscious awareness. (Cowey 1991, p. 103)

11 See the discussion of 'Coding and Content ' , in Dretske (1981, pp. 171-89). Dretskewrites:

What endows some systems with the capaci ty to occupy states which have, as theirsemant ic conten t , fac ts ab out some d is tan t source i s the p las t ic i ty of the sys tem forex t rac t ing in format ion about a source f rom a var ie ty of s igna ls . The sys tem, as i twere , ignores the par t icu la r messenger in order to re spond to the in form at ion de liv -e red by the messenger . . . . [The semant ic ] s t ruc ture i tse l f ca r r ies no in format ionabou t the m eans of i ts p roduc t ion (about the m essenger ) . ( Ib id . , p . 187)

12 See Dre tsk e ' s ingenious d iscuss ion of p r imary and secondary represen ta t ions in Dre t -ske (1981, pp. 156-65).13 Dretske (1981, pp. 111-23).14 Explici t rules can also be l imited to specif ic circumstances: one might , for instance,give a new em ploy ee a l is t of character is t ics which suff ice to ident ify the boss out of thosepersons work ing wi th the company, a l though the charac te ri s t ics would no t suff ice to p ickhim o ut o f a l l h i s fe l low res iden ts o f Manh at tan .15 Dretske (1969, pp. 124-39).16 Dretske (1981, p. 131 - with minor interpolat ions) .17 See the example of the Grabit family in Lehrer and Paxon (1969, pp. 228-29).18 Dretske (1971, pp. 6-7; i ta l ics omit ted) . Dretske adds that the detai ls of these con-d i t ions mus t inc lude no th ing which i s log ica l ly or causa l ly dependent upon the fac t o fwhich one c la ims knowledge .19 The d i ff icu lty i s s imi la r to what Richard Fe ldma n ca ll s Th e Prob lem of Ge nera l i tyin his 'Reliability and Justification' (1985, po 161).20 Dretske (1981, pp. 133-34); I wil l re turn in my penult imate paragraph to this dis t inctsort of context-relat ivi ty.zl Austin (1961, p. 52).22 Austin (1961, p. 66).23 Warnock (1962, pp. 19-32) .24 See Hanfl ing (1988, pp. 40-55) .2s Warnock (1962, p. 22).26 This might be the sor t o f th ing contemp la ted by Ann is whe n he wr i tes o f jus t if icat ion


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68 W I L L I A M S. B O A R D M A Nas being relati ve to the issue-con text ; see Ann is (1978, pp. 213-19). But his use of adefeasibility requirement (on p. 217) suggests that he does not see claims of knowledgeas being relative in the way I am suggesting.27 Austin (1961, pp. 67-71).2s Ebersole (1972, pp. 186-221).z9 See Welbourne (1979); but notice that such assurances will be relative to the contextin which they were given.3o See Harrison (1962, p. 453).3a See Dre tske 's original formu la (Dre tske 1981, p. 86). M y bold face addition impliesthat there n eed be no such thing as the inform ation that s is F: frequen tly there is, instead,the information that s is F rather than G the information that s is F rather than H andso forth, the relevant piece of information depending upon the worry specif ied by thecontext.32 See Austin (1961, fn. 1 on p. 76). Also Braine suggests that th e thresho ld varies withthe .sort of proposition in question (in Braine 1971, pp. 41-63). See also Dretske (1981,pp. 132-33).

R E F E R E N C E SAnnis, D .: 1978, 'A Contextual Theo ry of Epistemic Just if ication' , American Philosoph-ical Quarterly IS, 213-19.Austin, J. L.: 1961, 'Other Minds', in his Philosophical Papers Oxford Universi ty Press,

Oxford, pp. 44-84.Austin, J. L.: 1962, Sense and Sensibilia Oxford U niversi ty Press, Oxford.Ayer, A. J . : 1970, 'Has Austin Refuted the Sense-datum Theory?' , in his Metaphysicsand Common Sense Freeman, Cooper & Co. , San Francisco, pp. 127-30.Braine, D.: 1971, 'The Nature of Knowledge' , Proceedings o f the Aristotelian Society 72,

41-63.Cowey, A.: 1991, 'Grasping the Essentials', Nature 349, 102-03.Dretske, F. I.: 1969, Seeing and Knowing University of Chicago Press, Chicago.Dretske, F. I . : 1971, 'Conclusive Reason s' , Australasian Journal o f Philosophy 49, 1-22.Dretske, F. I.: 1981, Knowledge and the Flow of Information Bradford BookstMIT

Press, Cambridge, MA.Eberso le, F. : 1972, 'Saying and Me aning' , in A. Am brose and M. Lazerowitz (eds.) ,Ludwig Wittgenstein: Philosophy and Language Humanit ies Press, New York, pp.186-221.Feldman, R.: 1985, 'Reliability and Justification', The Monist 68, 159-74.Hanfl ing, O.: 1988, 'A Situat ional Account of Knowledge' , The Monist 68, 40-56.

Harman, G.: 1973, Thought Princeton University Press, Princeton.Harrison, J.: 1962, 'Knowing and Promising', Mind 71,443-57.Lehrer , K. and T. Paxon, Jr . : 1969, 'Knowledge: Unde feated Just ified True B elief ' ,

Journal of Philosophy 66, 225-37.Pitcher, G.: 1971, A Theory of Perception Princeton University Press, Princeton.Pollock, J. L.: 1974, Knowledge and Justification Princeton U niversi ty Press, Princeton.Warnock, G. J . : 1962, 'Claims to Knowledge' , Proceedings of the AristoteIian SocietySuppl. 36, 19-32.


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R E L A T I V I T Y O F P E R C E P T U A L K N O W L E D G E 69Welbo urne, M .; 1979, The Transmission of Know ledge , hilosophical Quarterly 29, 1-

9.Department of PhilosophyLawrence Universi tyAppleton, WI 54912U.S .A.

per(op)relativity preceptual knowledge

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