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Conclusive reasonsFred Dretske

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aUniversity of Wisconsin.

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D o w n l o a d e d B y : [ U n i v e r s i t y o f T o r o n t o ] A t : 1 5 : 1 0 1 1 M a y 2 0 0 7

Australasian Journa l of PhilosophyVol. 49, No. 1; May, 1971

F R E D D R E r S K E

C O N C L U S I V E R E A S O N S *

C o n c l u s i v e r e a s o n s h a v e a m o d a l a s w e l l a s a n e p i s te m i c c h a r a c t e r . I n

h a v i n g c o n c l u s i v e r e a s o n s t o b e l ie v e t h a t P is th e c a s e o n e ' s e p i s te m i c c r e d e n -

t ia ls a r e su c h a s t o e li m i n a t e t h e p o s s i b i l i t y o f m i s t a k e . T h i s , a t le a s t, ish o w I p r o p o s e t o u n d e r s t a n d t h e m f o r t h e r e m a i n d e r o f t h i s p a p e r . L e t t in g

t h e s y m b o l ' ( ) ' r e p r e s e n t t h e a p p r o p r i a t e m o d a l i t y ( a y e t t o b e c l ar if ie d s en s e

o f poss ib i l i t y ) , I s h a ll s a y , t h e n , t h a t R is a c o n c l u s i v e r e a s o n f o r P i f a n d

o n l y i f, g i v e n R , ~ ( ) ,-~ P ( o r , a l t e r n a t i v e l y , ~ ( ) ( R . ~ P ) ) . T h i s i n t e r -

p r e t a t i o n a l lo w s u s t o s a y o f a n y s u b j ec t , S , w h o b e l ie v e s t h a t P a n d w h o h a s

c o n c l u s iv e r e a s o n s f o r b e li e v in g t h a t P , t h a t , g i v e n t h e s e r e a s o n s , h e c o u Mn o t b e w r o n g a b o u t P o r , g i v e n t h e s e re a s o n s , i t i s f a l s e t h a t h e m ig h t b e

m i s ta k e n a b o u t P .

S u p p o s e , t h e n , t h a t

( I ) S k n o w s t h a t P a n d h e k n o w s t h is o n t h e b a si s (s i m p l y ) o f R e n ta i ls

( 2) R w o u l d n o t b e t h e c a s e u n l e s s P w e r e t h e c a s e . 1

T h e l a t t e r f o r m u l a e x p r e ss e s a c o n n e c t i o n b e t w e e n R a n d P w h i c h is s t r o n g

e n o u g h , I s u b m i t , t o p e r m i t u s t o s a y t h a t i f ( 2 ) is t r u e , t h e n R i s a c o n c l u s i v e

r e a s o n f o r P . F o r i f ( 2) is t r u e , w e a r e e n t i tl e d, n o t o n l y t o d e n y th a t , g i v e n R ,

n o t - P is t h e c a s e , b u t a l so t h a t , g i v e n R , n o t - P m i g h t b e t h e c a s e . T h a t is t o

s a y , ( 2 ) e l i m i n a t e s R a n d n o t - P a s a p o s s i b l e ( jo i n t ) s t a t e o f a f f a ir s a n d , w h e n

w e a r e g iv e n R , i t e l i m i n a t e s n o t - P a s a p o s s i b l e s t a t e o f a f f ai rs . T h i s is s ob e c a u s e ( 2 ) e n t a i l s t h e f a l s i t y o f ,

( 3) A l t h o u g h R is t h e c a s e P m i g h t n o t b e t h e c a s e .

I f w e e x p r e s s ( 3 ) a s ' G i v e n R , ( ) ,-~ P ' , t h e n ( 2) e n t a i l s t h a t i t is f a l se t h a t ,

g i v e n R , ( ) ~ P w h i c h is e q u i v a l e n t t o , g i v e n R , ~ ( ) ~ P ; a n d th i s is

p r e c is e ly t h e r e q u i r e d f e a t u r e o f c o n c l u s i v e r e a s o n s g i v e n a b o v e . H e n c e ,

w h e n ( 2 ) is t r u e , R i s a c o n c l u s i v e r e a s o n f o r P .

W h a t f o l l o w s is a n a m p l i f i c a t i o n o f t h e a b o v e s k e t c h - - h e n c e , a n a r g u m e n t

f o r th e v i e w t h a t i n th o s e c a s e s w h e r e k n o w l e d g e t h a t P r e st s o n e v i d e n c e ,

*An ear ly vers ion of th is pa per was read to the Ph i losophy D epar tm ent a t T he Uni -versi ty of I ll inois, Ch icago Circle. M ore recently i t was read at T he U niversi ty o f N or thCarol ina 's Col loquium in Phi losophy with Professor Robert Sleigh commenting.

x I shal l be using 'R ' and 'P ' to replace a variety o f related g ram ma tical uni ts . De pend ingon the sentential context, they sometimes serve as noun phrases, sometimes as fullindicat ive sentences, sometimes fo r appro priate t ransform ations o f the indicative.

1




F r e d D r e t s k e

g r o u n d s , o r r e a s o n s , w h e n t h e q u e s t i o n ' H o w d o e s S k n o w ? ' c a n s e n s i b l y

b e a s k e d a n d a n s w e r e d , t h e e v i d e n ce , g r o u n d s , o r r e a s o n s m u s t b e c o n c l u si v e .

A n y t h i n g s h o r t o f co n c lu s iv e r e a s o ns , t h o u g h i t m a y p r o v i d e o n e w i t h

j u s t if i e d t r u e b e l i ef s , f a il s t o g i v e t h e k i n d o f s u p p o r t r e q u i s i t e t o k n o w l e d g e .I s h a l l a l s o u r g e t h a t t h e p o s s e s s i o n o f c o n c l u s i v e r e a s o n s t o b e l i e v e , p r o p e r l y

q u a l i fi e d , is a l so a s u f fi c ie n t c o n d i t i o n f o r k n o w l e d g e .

1. K n o w i n g P o n t h e B a s i s o f R : T h e C o n n e c t io n B e t w e e n (1 ) a n d (2) .

S u p p o s e S , in o r d e r t o a s s ur e h i m s e l f t h a t h is c h i ld ' s t e m p e r a t u r e i s

n o r m a l ( n o f e v e r ) , p l a ce s a t h e r m o m e t e r i n t h e c h i l d 's m o u t h , e x t r a c t s ita f t e r se v e ra l m i n u t e s , a n d o b s e r v e s a r e a d i n g o f 9 8.6 ° F . I n r e m a r k i n g t o t h e

d o c t o r t h a t h i s c h i l d ' s t e m p e r a t u r e i s n o r m a l S i s a s k e d h o w h e k n o w s .

S r e s p o n d s , n a t u r a l l y e n o u g h , b y s a y in g , ' I j u s t t o o k h is t e m p e r a t u r e ' .L e t u s a s s u m e , t h e n , t h a t w e h a v e a n i n s t a n t i a t i o n o f ( 1 ):

( l a ) S k n o w s t h a t h i s c h i l d ' s t e m p e r a t u r e i s n o r m a l a n d h e k n o w s t h i s

o n t h e b as is o f t h e ( n o r m a l ) r e a d in g o n t h e t h e r m o m e t e r (w h i c h

h e h a s j u s t p l a c e d i n t h e c h i l d ' s m o u t h , e tc .) .

C a n o n e c o n s i s t e n t ly a f fi rm ( l a ) a n d d e n y th e c o r r e s p o n d i n g i n s ta n t i a t i o n o f

( 2 ) ?

( 2 a) T h e t h e r m o m e t e r w o u l d n o t h a v e r e a d 9 8 .6 ° u n l es s t h e c h i l d 's

t e m p e r a t u r e w a s n o r m a l .

I f it i s n o t a l r e a d y o b v i o u s t h a t o n e c a n n o t c o n s i s t e n tl y a ff ir m ( l a ) a n d d e n y

( 2 a) , I t h i n k i t c a n b e m a d e o b v i o u s b y c o n s i d e r in g th e k i n d o f t h in g w h i c h

w o u l d s h o w ( 2a ) t o b e fa ls e. F o r e x a m p l e , i f C h a r l es , f a m i l i a r w i t h t h e

p a r t i c u l a r t h e r m o m e t e r in q u e s t i o n , s h o u l d s a y , ' O h , I k n o w t h a t t h e r -

m o m e t e r ; i t i s f a i r ly a c c u r a t e f o r t e m p e r a t u r e s b e l o w 9 8 ° b u t i t s ti ck s a t

9 8 .6 f o r a l m o s t a n y h i g h e r t e m p e r a t u r e , ' w e h a v e b e e n g i v en s o li d g r o u n d s f o rr e j ec t in g ( 2 a) . S i m u l t a n e o u s l y , h o w e v e r , w e h a v e b e e n g i v en s o l id g r o u n d s

f o r re j e c t in g ( l a ) . I f i t is t h a t k i n d o f t h e r m o m e t e r , t h e n i f S 's o n l y b a si s f o r

t h i n k i n g h i s c h i ld ' s t e m p e r a t u r e n o r m a l i s a 98 .6 r e a d i n g o n i t , t h e n h e d o e s

n o t k n o w t h a t hi s c h i ld ' s t e m p e r a t u r e i s n o r m a l . I t might b e n o r m a l , o fc o u r s e , b u t i f S k n o w s t h a t i t is , h e m u s t h a v e m o r e t o g o o n t h a n t h e r e a d i n g

o n t h is ( d e f e c ti v e ) t h e r m o m e t e r .

O t h e r a t t e m p t s t o s h o w ( 2 a ) f a l s e h a v e t h e s a m e e f f e c t ; t h e y i m m e d i a t e l y

u n d e r m i n e R ( t h e r e a d i n g o n t h e t h e r m o m e t e r ) a s a n a d e q u a t e b a s i s f o r

s o m e o n e ' s k n o w i n g th a t t h e c h i l d 's t e m p e r a t u r e i s n o r m a l (P ) . F o r i n

r e j e c t i n g ( 2 a ) w e r e j e c t t h e t h e r m o m e t e r a s a r e l i a b l e d e v i c e f o r d i s c o v e r i n g

w h e t h e r a p e r s o n ' s t e m p e r a t u r e i s n o r m a l , a n d k n o w l e d g e i s n o t a c q u i r e d

b y r e l y i n g o n w h a t i s u n r e l i a b l e i n p r e c i s e l y t h o s e r e s p e c t s i n w h i c h w e r e l y

o n i t .

W e fr e q u e n t l y p u r p o r t t o k n o w t h in g s o n th e b as is o f t e s ti m o n y . J a m e s

h a s a l a rg e s t a m p c o l l e c t i o n a n d , a f t e r g iv i n g a d e t a i l e d d e s c r i p t i o n o f i t,

i n v i te s S to h i s h o m e t o s e e i t. S d e c l i n e s, b u t h e l a t e r r e f e r s t o J a m e s ' s t a m p

c o l l e c t io n i n c o n v e r s a t i o n . I t is e a s y e n o u g h t o i m a g i n e c i rc u m s t a n c e s i n

w h i c h i t w o u l d b e n a t u r a l f o r s o m e o n e t o a s k S h o w h e k n e w , w h a t r e a s o n s




C o n c l u s i v e R e a s o n s

h e h a d f o r th i n k i n g , t h a t J a m e s h a d s u c h a c o l le c t io n . A n d i t is j u s t a s e a s y

t o i m a g i n e S , i n r e s p o n s e t o s u c h a q u e r y , r e f e r r i n g t o h i s c o n v e r s a t i o n w i t h

J a m e s . L e t u s a s s u m e , t h e n , t h a t

( l b ) S k n o w s t h a t J a m e s h a s a s ta m p c o l le c t io n a n d h e k n o w s th is o n t h eb a s is o f J a m e s ' d e s c r i p t i o n ( a n d i n v i t a t i o n )

is t r ue . I a m n o t n o w c o n c e r n e d t o a r g u e t h a t o n e c a n k n o w s o m e t h i n g

o f t hi s s o r t i n t h is w a y ; t h e q u e s t i o n is , r a t h e r , w h e t h e r ( 2 b ) m u s t b e t r u e / f

( l b ) i s t r u e .

( 2 b) J a m e s w o u l d n o t h a v e s a id h e h a d a s t a m p c o l le c t i o n , d e s c r i b e d

i t i n s u c h d e t ai l, a n d i s s u e d a n i n v i t a t i o n u n l e s s h e h a d a s t a m p

c o l l e c t i o n .

I f J a m e s i s t h e s o r t o f f e l l o w a b o u t w h i c h ( 2 b ) c a n n o t b e t r u l y a s s e rt e d , t h e nh e is n o t t h e s o r t o f f e ll o w w h o c a n b e t r u s t e d o n s u c h m a t t e r s a s t hi s. I f

J a m e s is t h e s o r t o f f e ll o w w h o s o m e t i m e s s a y s s u c h t h i n g s a s a j o k e , w h o

w o u l d ( o r m i g h t ) c o n c o c t s u c h e l a b o r a t e s to r ie s f o r h i s o w n a m u s e m e n t

( o r w h a t e v e r ) , w h o w o u l d ( o r m i g h t ) w h i m s i c a l ly is su e a n i n v i t a t i o n o f th is

s o r t u n d e r t o t a l l y f al se p r e te x t s , t h e n , d e s p i t e t h e f a c t t h a t h e is ( b y h y p o -

t h e s i s ) t e l l i n g t h e t r u t h o n t h i s o c c a s i o n , h i s t e s t i m o n y i s h a r d l y t h e s o r t o n

w h i c h o n e c a n re s t a c l a im t o k n o w . I n d e n y i n g ( 2 b) o n e is c o n c e d i n g t h a t

J a m e s w o u l d , o r m i g h t , h a v e s a id w h a t h e d id w i t h o u t p o s s e ss i ng a s t a m p

c o l l e c ti o n , a n d i n t h e l ig h t o f th i s c o n c e s s i o n o n e c a n n o t g o o n t o i n s is t th a t ,

n o n e t h e l e s s , S k n o w s h e h a s a s t a m p c o l l e c ti o n o n t h e b a s is , s i m p l y , o f w h a t

J a m e s s a i d .

I n a r e c e n t a rt ic l e G i l b e r t H a r m a n c o n t r a s t s t w o c a s e s, t h e l o t t e r y c a s e

a n d t h e t e s t i m o n y c a s e . 2 A l t h o u g h S , s ay , h a s o n l y o n e a m o n g t h o u s a n d s o f

t ic k e ts i n a l o t t e r y a n d , h e n c e , h a s a n e x t r e m e l y s l e n d e r c h a n c e o f w i n n i n g ,

w e n a t u r a l l y r e j e ct th e i d e a t h a t S c o u l d k n o w t h a t h e w a s g o i n g t o lo s e o n t h e

b a s is o f a c o r r e c t p r o b a b i l i t y e s t im a t e ( w e ll o v e r 9 9 . 9 % ) o f h i s l o si n g . E v e n

i f S c o r r e c t l y p r e d i c ts t h a t h e i s g o i n g t o l o se , w e w o u l d d e n y t h a t h e k n e w h e

w a s g o i n g t o l o s e i f t h e o n l y b a s i s h e h a d f o r t h is b e l i e f w a s t h e f a c t t h a t h isc h a n c e s o f w i n n i n g w e r e s o s lig h t, s H a r m a n c o m p a r e s t h is c a s e w i t h t h e

s i tu a t io n i n w h i c h w e o f te n s e e m p r e p a r e d t o s ay t h a t S k n o w s t h a t P w h e n

h e is t o l d t h a t P is t h e c as e b y s o m e o t h e r p e r s o n ( t e s t i m o n y c a se ) . A l t h o u g h

p r o b a b i l i t y e s ti m a t e s a re n o t a l t o g e th e r a p p r o p r i a t e h e r e , w e d o k n o w t h a t

p e o p l e s o m e t i m e s l ie , s o m e t i m e s t h e y a r e h o n e s t l y m i s t a k e n , a n d s o o n .

T h e r e a l w a y s s e e m s t o b e a c h a n c e t h a t w h a t a p e r s o n t e l l s u s i s n o t t h e c a s e

h o w e v e r s in c e re o r c re d ib l e h e m a y a p p e a r , a n d t h e o r d e r o f m a g n i t u d e o f

2 'Kno wled ge, Inference, and Ex plana t ion ' , in American Philosophical Quarterly, July,1968.

8 O f course S m ay have sa id ' I kn ow I am going to lose ' and he m ay say now, af ter he haslost , ' I knew I was going to lose ' , but these expressions are normally accepted withoutepistemological quibbling because the y are tak en a s li tt le m ore th an expressions o f resig-nat ion o r despair . W i th th is use of the verb ' to k now ' , one can kno w one i s going tolose and s t i l l spend a dol lar for a ticket an d a ch ance at the prize---a fact abou t hum anbeings which is puzzling if they believe they know (in any epistemologically relevantsense) that they are going to lose.

3




Fred Dretske

t h is c h a n c e s e e m s t o b e c o m p a r a b l e t o t h e c h a n c e w e m i g h t w i n i n s o m e

a p p r o p r i a t e l o t t e r y s i tu a t i o n . W h y , t h e n , a r e w e p r e p a r e d t o s a y t h a t w e

k n o w i n t h e o n e c a s e b u t n o t i n t h e o t h e r ? H a r m a n h a s s o m e r e v e a l in g

r e m a r k s t o m a k e a b o u t t h e s e c a s e s , b u t I m e n t i o n t h e m o n l y to b r i n g o u tt h e i r r e l e v a n c e t o t h e p r e s e n t d i s c u s s i o n . F o r I t h i n k th i s c o n t r a s t s t re n g t h e n s

t h e v i e w t h a t ( 2 ) i s n o r m a l l y a c c e p t e d a s a n e c e s s a r y c o n s e q u e n c e o f (1 ) ,

t h a t w h e n w e a r e u n w i l l i n g t o e n d o r s e t h e c o r r e s p o n d i n g i n s t a n t i a t i o n o f

( 2 ) w e a r e u n w i l l i n g t o t a l k o f a n y o n e k n o w i n g t h a t P i s t h e c a s e o n t h e b a s i s

o f t h e e v i d e n c e e x p r e s s e d b y R . I n m a n y t e s t i m o n y s i t u a t io n s w e a r e , I

b e l ie v e , w i l l i n g t o a f f i r m ( 2 ): t h e p e r s o n w o u l d n o t h a v e s a i d i t u n l e s s i t w a s

s o . I n t h e l o t t e r y c a s e , h o w e v e r , t h e c o n n e c t i o n b e t w e e n R a n d P e x p r e s s e d

b y t h i s s u b j u n c t i v e c o n d i t i o n a l f a il s t o b e r e a l i z e d , a n d i t f a i l s n o m a t t e r h o w

g r e a t th e p r o b a b i l i t i e s b e c o m e . A d j u s t i n g t h e w o r d i n g o f ( 2 ) t o s u i t t h e

e x a m p l e i n q u e s t i o n 4 w e h a v e

( 2 c) I f S w e r e g o i n g t o w i n t h e l o t t e r y , h i s c h a n c e s o f w i n n i n g w o u l d

n o t b e 1 / m ( m b e i n g t h e n u m b e r o f t i c k e t s s o ld ) .

W h a t e v e r ( f i n i te ) v a lu e w e g iv e t o ' m ' , w e k n o w t h is is f a ls e s i n c e s o m e o n e

w h o s e c h a n c e s o f w i n n i n g a r e 1 / m will w i n , a n d s in c e t h e r e i s n o t h i n g s p e c i a l

a b o u t S w h i c h w o u l d r e q u i r e h i m t o h a v e a b e t t e r c h a n c e o f w i n n i n g t h a n

a n y o n e e l se i n o r d e r t o w i n , w e r e j e c t ( 2 c) a s f a l s e . H e n c e , w e r e j e c t t h e i d e a

t h a t S c a n k n o w h e i s g o i n g t o l o s e o n t h e b a s i s o f t h e f a c t t h a t h i s c h a n c e s o f

l o s in g a r e ( m - 1 ) / m .A l v i n G o l d m a n , i n d e v e l o p i n g a c a u s a l a c c o u n t o f k n o w l e d g e , c o n s t r u c t s a

s i t u a t i o n i n w h i c h S i s sa i d to k n o w t h a t a n e a r b y m o u n t a i n ( I w i l l c a l l i t M )

e r u p t e d m a n y y e a r s a g o . H e k n o w s t h i s o n t h e b a s i s o f t h e p r e s e n c e o f

s o l id i f i e d l a v a t h r o u g h o u t t h e c o u n t r y s i d e s u r r o u n d i n g t h e m o u n t a i n . 5

A c c o r d i n g t o G o l d m a n , a n e c e s s a r y c o n d i t i o n fo r S ' s k n o w i n g t h a t M

e r u p t e d m a n y y e a r s a g o o n t h e b a s i s o f t h e p r e s e n t ex i s t e n c e a n d d i s t r i b u t i o n

o f t h e l a v a is th a t t h e r e b e a c a u s a l c o n n e c t i o n b e t w e e n t h e e r u p t i o n o f th e

m o u n t a i n a n d t h e p r e s e n t e x is t en c e a n d d i s t r i b u t i o n o f t h e l a v a . I d o n o t

4 T h e wo rd i n g o f (2) w i l l s o m e t i m es h av e t o b e a d j u s t ed t o s u it t h e p a r t i cu l a r i n s t an t ia t i o ni n q u es ti o n . T h e ch i e f f ac t o r s d e te rm i n i n g th i s ad j u s t m en t a r e t h e r e l a t iv e t em p o ra ll o ca t i o n s o f R , P an d t h e t i m e o f u t t e ran ce an d a l s o th e cau s a l co n n ec t io n s , i f an y , wh i cha re b e li ev ed t o h o l d b e t ween R an d P . T h e p a r t i cu l a r wo rd i n g I h av e g i v en (2) i s m o s tap p ro p r i a t e wh en P i s s o m e s t a t e o f a f f a i r s an t eced en t t o (o r co n t em p o ran eo u s wi t h )b o t h R an d t h e t i m e o f u tt e r an ce . T h i s , o f co u rs e , i s t h e r e su l t o f t h e f ac t th a t (2) ism o s t o f t en u s ed w h en P i s s o m e s t a t e o f a f f a i rs cau s a l l y r e s p o n s i b l e fo r t h e p re s en tco n d i t i o n R . W h en P i s a fu t u re s ta t e we m i g h t ex p re s s (2) a s : R wo u l d n o t b e t h e ca s eu n l es s P w ere g o i n g t o h ap p en . Fo r ex am p l e , h e wo u l d n o t h av e r eg i s te r ed u n l es s h ewere g o i n g t o v o t e . I d o n o t w i sh t o p rec l u d e t h e p o s s i b i li t y o f k n o wi n g t h a t s o m e t h i n g

will o ccu r o n t h e b as i s o f p re s en t ev id en ce b y r e s t r ic t i n g t h e w o rd i n g o f (2) . T h ed if ficu lty, o f course , i s tha t when P i s som e fu tu re s ta te , the sub junct ive re la t ing i t to Rg en e ra l ly b eco m es so m ew h a t q u es t io n ab l e . W e p re fe r t o s ay , i n o u r m o re cau t i o u sm o o d s , t h a t i f h e w e re n o t planning to vo te , he w ould no t have reg is te red (acknowledg ing ,thereby , the fac t tha t con t ingencies may in te r fe re wi th the execu t ion o f h i s p lans ) .B u t i n t h e s am e cau t i o u s m o o d s w e p re fe r t o s ay , n o t t h a t w e k n o w h e i s g o i n g to v o t e(b ecau s e h e r eg is t e red ) , b u t t h a t we k n o w h e p l an s o r i n t en d s t o v o t e .' A C a u s a l T h e o r y o f K n o w i n g ', Journal of Philosophy, Jan e 22, 1967, p . 361.

4





w i s h t o d i s p u t e t h i s c la i m a t t h e m o m e n t s in c e t h e v i ew I a m a d v a n c i n g i s e v e n

s t r o n g e r : v iz . t h a t a n e c e s s a ry c o n d it io n f o r S t o k n o w t h a t M e r u p t e d o n

t h is b a s i s i s t h a t

( 2d ) T h e l a v a w o u l d n o t b e h e r e , a n d d i s t r ib u t e d i n t h is m a n n e r , u n l e s sM e r u p t e d

i s t r u e . ( 2 d) is a s t r o n g e r c l a i m t h a n t h a t th e e r u p t i o n o f M i s c a u s a l l y

c o n n e c t e d w i t h t h e p r e s e n t e x i s te n c e a n d d i s t r ib u t i o n o f t h e l a v a . ( 2 d ) r e -

q u i re s , in a d d i t i o n , t h a t M ' s e r u p t i o n b e n e c e s s a r y f o r t h e p r e s e n t s t a t e o f

a f fa ir s. T o il lu s t ra t e , c o n s i d e r th e f o l lo w i n g e m b e l l i s h m e n t o n G o l d m a n ' s

e x a m p l e. N o t f a r f r o m M is a n o t h e r m o u n t a i n , N . T h e g e o l o g y o f t h e

a r e a i s s u c h t h a t a t t h e p o i n t i n t i m e a t w h i c h M e r u p t e d s o m e t h i n g , s o t o

s p e a k, w a s b o u n d t o g i ve ; i f M h a d n o t e ru p t e d , N w o u l d h a v e . F u r t h e r -

m o r e , t h e l o c a t i o n o f N i s s u c h t h a t i f i t, ra t h e r t h a n M , h a d e r u p t e d , t h ep r e s e n t d i s t r i b u t io n o f la v a w o u l d h a v e b e e n , i n a l l r e s p e c t s re l e v a n t t o S ' s

t a k i n g i t a s a r e a s o n f o r b e l ie v i n g M e r u p t e d , t h e s a m e . I n s u c h c i r c u m -

s t an c e s G o l d m a n ' s n e c e s s a r y c o n d i t i o n i s s a ti sf ie d , b u t m i n e i s n o t . ( 2d ) i s

f a l s e ; i t i s f a l s e t h a t t h e l a v a w o u l d n o t b e h e r e , a n d d i s t r i b u t e d i n t h is f a s h i o n ,

u n le s s M h a d e r u p t e d . F o r if , c o n t r a r y t o h y p o t h e s i s , M h a d n o t e r u p t e d ,

N w o u l d h a v e ; l e a v i n g th e v e r y s a m e ( re l e v a n t) tr a c e s.

I n s u c h c ir c u m s t a n c e s I d o n o t t h i n k w e c o u l d s a y t h a t S k n e w t h a t M

e r u p t e d o n t h e b a s is o f t h e p r e s e n t e xi s te n c e a n d d i s t r ib u t i o n o f l a v a . F o r ,

b y h y p o t h e s i s , th i s s t at e o f a f fa ir s w o u l d h a v e o b t a i n e d w h e t h e r M e r u p t e do r n o t a n d , h e n c e , t h e r e i s n o t h i n g a b o u t t h is s t a t e o f a f fa i rs w h i c h f a v o u r s

o n e h y p o t h e s i s ( M e r u p te d ) o v e r a c o m p e t i n g h y p o t h e s i s ( N e r u p t e d ). S

i s s t i l l c o r r e c t i n s u p p o s i n g t h a t M d i d e r u p t , s t i l l c o r r e c t i n s u p p o s i n g t h a t

i t w a s M ' s e r u p t i o n w h i c h i s c a u s a l l y r e s p o n s i b l e f o r t h e p r e s e n t e x i s t en c e

a n d d i s t r ib u t i o n o f l a v a, b u t h e d o e s n o t k n o w i t w a s M t h a t e r u p t e d - - n o t

u n le s s h e h a s s o m e a d d i ti o n a l g r o u n d s w h i c h p re c l u d e N . I f h e h a s s uc h

a d d i t io n a l g r o u n d s , c a ll t h e m Q , t h e n w e c a n s a y th a t h e k n o w s t h a t M

e r u p t e d a n d h e k n o w s t h i s o n t h e b a s i s o f R a n d Q . I n t h i s c a s e , h o w e v e r ,

t h e c o r r e s p o n d i n g i n s t a n t i a t i o n o f ( 2) i s a l s o s a ti s f ie d : R a n d Q w o u l d n o tb e t h e c a s e u n l e s s M e r u p t e d . A s th i n g s s t a n d , t h e m o s t t h a t S c o u l d k n o w ,

o n t h e b a s i s s i m p l y o f th e p r e s e n t e x i s te n c e a n d d i s t r i b u t i o n o f l a v a , is t h a t

e i t h e r M o r N e r u p t e d . (2 ) p e r m i t s u s to s a y th is m u c h , a n d n o m o r e , a b o u t

w h a t c a n b e k n o w n o n t h e b a s is o f la v a fl ow .

T h e c a s e b e c o m e s e v e n c l e a re r if w e e x p l o it a n o t h e r o f H a r m a n ' s e x a m p l e s .6

H a r o l d h a s a ti c k e t i n a lo t t e ry . T h e o d d s a g a i n s t h is w i n n i n g a r e 1 0 ,0 0 0 t o 1 .

T h e p r i z e , c a l l i t a n X , i s s o m e t h i n g t h a t H a r o l d d o e s n o t n o w h a v e n o r

c o u l d h e r e a s o n a b l y e x p e c t t o o b t a i n o n e b y m e a n s o t h e r t h a n w i n n i n g t h e

l o tt e ry . E n t e r a p h i l a n t h r o p i c g e n tl e m a n , R o c k a f o r d , w h o d e c id e s t o g iv eH a r o l d a n X i f ( a s se e m s li k e ly ) h e s h o u l d f a il t o w i n o n e i n t h e l o t t e ry .

T h i n g s 3 o a s o n e w o u l d e x p e c t ; H a r o l d h o l d s a l o si n g t ic k e t. R o c k a f o r d

k e e p s h is w o r d a n d g i ve s H a r o l d a n X . S , f a m i l i a r w i t h t he a b o v e c i rc u m -

s ta n c e s b u t u n a w a r e o f w h e t h e r H a r o l d w o n o r l o s t i n t he l o t te r y , fi nd s

o In 'Know ledge, Inference, and Explanation', pp . 168-9. I have adapted the examplesomewhat.





Har old with his newly acquired X. S infers that Haro ld received his X from

Roekaford. He concludes this because he knows that the only other wayHarold might have acquired an X is by winning the lottery and the odds

against that happening are enormous . The following conditions are satis-fied: (a) Harold received his X from Rockaford; (b) S believes that Harold

received his X from Rockaford; (c) S is warranted in believing this since the

chances of his having received it in any other way are negligible; (d) Rocka-

ford's generous gift of an X to Harol d is the (causal ?) explanation of Haro ld' s

present possession of an X; and, finally (e) S correctly reconstructs (to use

Goldman's language) the causal chain of events which brought about

Haro ld's possession of an X. Yet, why does it seem clear (at least to myself---and apparently to Harman) and S does n o t know that Rockaford gave

Harold his X. Because(2e) Harold would not have an X unless Rockaford gave him one

is plainly false.7 If Rockaford had no t given him an X, it would have been

because Harold already possessed one as a winner in the lottery. Hence,

Harold would possess an X even if Rockaford had not given him one.

It is not true that R would not be the case u n l e s s P; hence, not true that S

knows tha t P on the basis o f R. s

(2), therefore, expresses something stronger than a causal relationship

between R and P. It should be pointed out, however, that it expresses

something which is, in certain important respects, weaker than a universal

association between states or condit ions similar to R and states or conditions

similar to P. When 'R ' and 'P' are expressions which stand for particular

conditions or states of affairs, as will often be the case when we know one

thing on the basis of something else, (2) expresses a connection between more

d e t e r m i n a t e states of affairs than those described by talking about states

similar to R and P. If someone remarks, mid-way through a poker hand,

that if his neighbour had not folded (dropped from the game) he (the speaker)

would have been dealt a royal flush, he is obviously not maintaining that

w h e n e v e r his neighbour remains in the game, he (the speaker) is rewarded

with a royal flush. Rather, he is talking about t h i s hand (already holding

four cards to the royal flush), t h i s p a r t i c u l a r distribution of cards in the

remainder of the deck, t h i s p a r t i c u l a r seating arrangement, and so on.

He is not saying tha t his neighbour' s remaining in the game is, quite generally,

sufficient for his receipt of a royal flush. Rather , he is saying tha t i n t h e

7 There is a way of reading (2e) which makes it sound true--viz , if we illicitly smuggle inthe fact that Harold has lost the lottery. That is, (2e') 'Harold, having lost the lottery,would not have an X unless Rockaford had given him one', is true. But this version of(2) makes R, the reason S has for believing Rockaford gave him an X, not only Harold'spossession of an X but also his having lost the lottery. This, by hypothesis, is not partof S's reason; hence, not properly included in (2e). (2e) must be read in something likethe followingfashion: Harold would not have an X, whatever the outcome of the lottery,unless Rockaford had given him one. With this reading it is clearly false.

s It is difficult to say whether this is a counter-example to Goldman's analysis. I think itsatisfies all the conditions he catalogues as sufficient for knowledge, but this depends onhow strictly Goldman intends the condition that S must be warranted in inferring thatP is the case from R.

6




C o n c l u s i v e Re a so n s

p a r t ic u l a r c i r c u m s t a n c e s w h i c h i n f a c t p re v a i l e d o n t h i s o c c a s io n , circumstances

which include such things as ca rd distribution, arrangement of players, etc.,

an occurrence of the first sort (neighbour remains in game) will invariably

be followed by one o f the second sort (his receipt of a royal flush). Onecannot falsify his claim by showing that he would not have received a royal

flush, despite his neighbour's remaining in the game, if the card distribution

in the deck had been different from what it in fact was. Fo r his claim was a

claim about the inevitable sequence of events w i t h t h a t d i s t r ib u t i o n o f c a rd s .

Statements such as (2), then, even when R and P are expressions for par-

ticular states of affairs, express a general uniformity, but this general uni-

formity is not that whenever a state similar to R is the case, then a state

similar to P will also be (or have been) the case. The uniformi ty in question

concerns the relationship between states similar to R and P u n d er a f i x e dse t o f c i r c u m s t a n c e s . Whenever (a state such as) R i n c i r c u m s t a n c e s C then

(a state such as) P where the circumstances C are defined in terms of those

circumstances which actually prevail on the occasion of R and P. But does

C include a ll the circumstances that prevail on the occasion in question or

only s o m e of these? Clearly not all the circumstances since this would

trivialize every subjunctive condi tional of this sort. Even if we restrict C

to only those circumstances logically independent of R and P we still obtain

a trivialization. For, to use Goldm an 's moun tain example (as embellished),

C would still include the fact that N did not erupt (since this is logicallyindependent of bo th R and P), and this is obviously one o f the circumstances

n o t held fixed when we say that the lava would not be here unless M erupted.

For in asserting his subjunctive we mean to be asserting something which

would be f a l s e in the situation described (N would have erupted if M had

not) whereas if we hold this circumstance (N did not erupt) fixed, the uni -

formity between the presence of lava and M's eruption would hold .

I think that our examples, not to mention an extensive literature on the

subject, 9 point the way to a proper interpretation of C. The circumstanceswhich are assumed constant, which are tacitly held fixed, in conditionals

such as (2), are those circumstances prevailing on the occasion in question

(the occasion on and between which the particular states R and P obtain)

which are logically and causally independent of the state of affairs expressed

9 I am not proposing a solution to the problem to which Nelson Goodman (Fact, Fictionand Forecast, Chapter I), Roderick Chisholm ('The Contrary-to-Fact Conditional,"Mind, 55, 1946) and others addressed themselves in trying to specify the 'relevant con-ditions' associated with counterfactuals. I shall use the notion of 'causality' in mytreatment, a device which both Goodman and Chisholm would regard as question-begging. I am not, however, attempting to offer an extensionalist analysis of the sub-junctive conditional; I am merely trying to get clear in what way such conditionals arestronger than the statement of a causal relationship between R and P and yet (in onesense) weaker than a statement of the universal association between states similar toRand P.




Fred Dretske

b y p.1 0 W h e n w e h a v e a s t a t e m e n t in t h e s u b j u n c t i v e w h i c h ( u n l i k e ( 2 ))

i s c o u n t e r f a c t u a l ( t h e a n t e c e d e n t g i v e s e x p r e s s i o n t o a s t a t e o f a f f a i r s w h i c h

d o e s o r d i d n o t o b t a i n ) , t h e n C i n c l u d e s th o s e c ir c u m s t a n c e s p r e v a i li n g o n t h e

o c c a s i o n w h i c h a r e l o g i ca l ly a n d c a u s a l ly i n d e p e n d e n t o f t h e s t a te o f a f fa ir s( o r l a c k o f s u c h s t a t e ) e x p r e s s e d b y t h e a n te c e d e n t o f t h e c o n d i t i o n a l . I n

o u r p o k e r g a m e , f o r e x a m p l e , w e c a n s a y t h a t S ' s s ta t e m e n t (I w o u l d h a v e

g o t a r o y a l f lu s h i f m y n e i g h b o u r h a d s t ay e d i n th e g a m e ) f i x e s t h a t s e t o f

c i r c u m s t a n c e s w h i c h a r e l o g i c al ly a n d c a u s a ll y i n d e p e n d e n t o f h i s n e i g h b o u r ' s

s t a y i n g in t h e g a m e ( i .e . t h e a n t e c e d e n t s i nc e t h e s t a t e m e n t is c o u n t e r f a c t u a l ) .

H e n c e , i f t h e r e is a n o t h e r p l a y e r i n t h e g a m e ( w h o s e p r e s e n c e o r a b s e n c ea f fe c ts t h e c a r d s d e a l t t o S ) w h o w o u l d h a v e d r o p p e d i f S 's n e i g h b o u r h a d

n o t d r o p p e d , t h e n t h i s p e r s o n ' s r e m a i n i n g i n t h e g a m e i s n o t h e l d f ix e d , n o t

i n c l u d e d i n C , b e c a u s e i t i s c a u s a l l y c o n n e c t e d t o t h e s t a t e o f a f f a i rs e x p r e s s e db y th e a n t e c e d e n t i n S 's s t a te m e n t . T h e r e f o r e , w e c a n s h o w S ' s s t a t e m e n tt o b e f a l s e i f w e c a n s h o w t h a t s u c h a c i r c u m s t a n c e p r e v a i l e d , a n d i t i s a l o n g

t h e s e l i n e s t h a t o n e w o u l d s u r e l y a r g u e i n a t t e m p t i n g t o s h o w S t h a t h e

w a s w r o n g , w r o n g i n s a y in g th a t h e w o u l d h a v e r e c e iv e d a r o y a l f lu s h i f h i sn e i g h b o u r h a d s t a y e d i n t h e g a m e .

O n t h e o t h e r h a n d , o n e c a n n o t s h o w t h a t S 's s t a t e m e n t is f a ls e b y s h o w i n gt h a t , w e r e t h e c a r d s d i f f e re n t ly a r r a n g e d i n th e r e m a i n d e r o f t h e d e c k , h e

w o u l d n o t h a v e r e c ei v e d h is r o y a l fl u s h ; f o r t h e a r r a n g e m e n t o f c a r d s i n t h e

r e m a i n d e r o f t h e d e c k ( u n l ik e t h e p r e s e n c e o r a b s e n c e o f o u r o t h e r p l a y e r )is ( p r e s u m a b l y ) i n d e p e n d e n t o f S 's n e i g h b o u r ' s d e p a r t u r e f r o m t h e g a m e .

H e n c e , i t i s o n e o f th e c o n d i t i o n s h e l d f i x e d , i n c l u d e d i n C , b y S ' s s t a t e m e n t ,

a n d w e a r e n o t a l l o w e d t o c o n s i d e r a l t e r a t i o n s i n i t i n a s s e s s i n g t h e g e n e r a li m p l i c a t io n o f S ' s s t a t e m e n t .

O r c o n s i d e r o u r o r i g in a l t h e r m o m e t e r e x a m p l e . R e c a ll , t h e s t a t e m e n t i n

q u e s t i o n w a s : ' T h e t h e r m o m e t e r w o u l d n o t h a v e r e a d 9 8 .6 ° u n l es s t h e c h i ld ' s

t e m p e r a t u r e w a s n o r m a l . ' S u p p o s e s o m e o n e r e sp o n d s , ' O h , it w o u l d h a v e( o r m i g h t h a v e) if t h e th e r m o m e t e r w a s b r o k e n . ' I t is i m p o r t a n t t o u n d e r -

s t a n d t h a t o n e c a n g r a n t t h e t r u t h o f th is r e s p on s e w i t h o u t a b a n d o n i n g t h eo r i g i n a l a s s e r t i o n ; f o r t h e o r i g i n a l a s s e r t i o n h a d , a s i t s g e n e r a l i m p l i c a t i o n ,

n o t a s t a t e m e n t e x p r e s s i n g a u n i f o r m r e l a t i o n s h i p b e t w e e n s t a t e s o f a f fa i rss i m i l a r t o t h e c h i l d ' s t e m p e r a t u r e ( n o r m a l b o d y t e m p e r a t u r e ) a n d s t a t e s o fa f fa i rs s i m i l a r t o t h e t h e r m o m e t e r r e a d i n g ( a r e a d i n g o f 98 .6 ) , b u t , r a t h e r , a

u n i f o r m i t y b e t w e e n s u c h s t a t e s u n d e r a f i x e d s e t o f c ir c u ms ta n c es . A n d , i f

10 T h i s c h a r a c t e r i z a t i o n o f t h e c i r c u m s t a n c e s ' C ' h a s i n t e r e s t i n g a n d , I b e l i e v e , s i g n if i c an t

r e p e r c u s s i o n s f o r s u b j u n c t i v e s h a v i n g t h e f o r m o f ( 2) in w h i c h R e x p r e ss e s so m e p r e s e n t( o r p a s t ) s t a t e o f a ff a ir s a n d P e x p r e s se s s o m e f u t u r e s t a t e o f a f fa i rs . A l t h o u g h I l a c k t h e

s p a c e t o d i sc u s s t h e p o i n t h e r e , I b e l i ev e a n i m p o r t a n t a s y m m e t r y is g e n e r a t e d b y a s h i f ti n t h e r e l a ti v e t e m p o r a l l o c a t i o n s o f R a n d P . I a ls o be l ie v e , h o w e v e r , t h a t t h i s a s y m -m e t r y i s f a i th f u l l y re f l ec t e d i n t h e d i f f e r en c e b e t w e e n k n o w i n g w h a t will h a p p e n o n t h eb a si s o f p r e s e n t d a t a a n d k n o w i n g w h a t did h a p p e n o n t h e b a s is o f p r e s e n t d a t a . I no t h e r w o r d s , I f e el t h a t a n a s y m m e t r y i n ( 2 ), a r i si n g f r o m a s h i f t in t h e r e l a t i v e t e m -p o r a l l o c a t i o n s o f R a n d P , h e l p s o n e t o u n d e r s t a n d t h e d i f fe r e n c e w e a l l f e el b e t w e e nk n o w i n g , o n t h e o n e h a n d , w h a t d i d h a p p e n o r i s h a p p e n i n g , a n d , o n t h e o t h e r h a n d ,w h a t w i l l h a p p e n .




Conc lus ive Reasons

I a m f i g h t , th i s f i x e d se t o f c i r c u m s t a n c e s i n c l u d e s t h e a c tu a l s t a t e o f t h ethermometer ( d e f e c t i v e o r a c c u r a t e ) ; i t is o n e o f t h o s e c i r c u m s t a n c e s p r e v a i l i n g

o n t h e o c c a s i o n i n q u e s t i o n w h i c h i s c a u s a ll y a n d l o g i ca l ly i n d e p e n d e n t o f

t h e c h i ld ' s t e m p e r a t u r e . H e n c e , t h is c i r c u m s t a n c e c a n n o t b e a l l o w e d tov a r y a s it is in t h e a b o v e r e s p o n s e b y t h e w o r d s ' i f t h e t h e r m o m e t e r w a s

b r o k e n ' . T o d e t e r m i n e t h e t r u t h o f t h e o r i g in a l a s s e r t i o n w e m u s t s u p p o s e

t h a t t h e t h e r m o m e t e r i s a c c u r a te ( o r d e f e ct iv e ) whatever the ac tua l cond i tion i s.I f, t h e r e fo r e , t h e t h e r m o m e t e r w a s n o t b r o k e n o r o t h e r w i s e d e f e c ti v e o n t h a t

o c c a s i o n , t h e n t h e s u g g e s t i o n t h a t i t w o u l d ( o r m i g h t ) h a v e r e a d t h e s a m e

d e s p it e a f e v e r i s h c h i l d i f i t w e r e b r o k e n o r d e f e c t iv e is , a l t h o u g h q u i t e t r u e ,

i rr e le v a n t t o t h e t r u t h o f th e s t a t e m e n t : ' I t w o u l d n o t h a v e r e a d 9 8 . 6 u n l es s

t h e c h i ld ' s t e m p e r a t u r e w a s n o r m a l . '

O n e fi n a l i m p o r t a n t f e a t u r e o f ( 2 ). I h a v e s a id t h a t , g e n e r a l l y s p e a k i n g ,t h e p l a c e - h o l d e r s ' R ' a n d ' P ' r e p r e s e n t e x p r e s s i o n s d e s i g n a t i n g speci f ic s ta tes

o f a f fa i rs o r c o n d i t i o n s . W h e n t h is is s o , ( 2 ) s ti ll h a s a g e n e r a l i m p l i c a t i o n ,

b u t t h e g e n e r a l i m p l i c a t i o n , e x p r e s s i n g a u n i f o r m r e l a t i o n s h i p b e t w e e n

s ta te s o f a ff a ir s si m i l a r t o R a n d P , has i t s scope res t r ic ted t o s i t u a t i o n s i n

w h i c h t h e c i rc u m s t a n c e s C ( as s p e c if i ed a b o v e ) o b t a i n . S i n c e w e a r e t a l k i n g

a b o u t s p e c if ic s t a t es o f a f fa i rs i n m o s t i n s t a n t i a t i o n s o f (2 ), i t b e c o m e s

e x t r em e l y i m p o r t a n t t o o b s e r v e th e s o r ts o f r e f e rr i n g e x p r e s s io n s e m b o d i e d

w i t h in b o t h ' R ' a n d ' P ' . F o r e x a m p l e , w h e n I s ay , ' J o h n w o u l d n o t h a v e s ai d

i t w a s r a i n i n g u n l e s s i t w a s r a i n i n g ' I a m t a l k i n g a b o u t John a n d a b o u t apar t icu lar u t t e rance o f h i s . S o m e o n e e l s e m i g h t h a v e s a i d t h i s w i t h o u t i t s

b e i ng t r u e ; J o h n m a y h a v e s a id someth ing e l se w i t h o u t i ts b e i n g t r u e . N o n e -

the less , John w o u l d n o t h a v e s a id i t was raining u n l e s s i t w a s . A n i n c u r a b l e

l ia r a b o u t m o s t t h i n g s, J o h n h a s a p a t h o l o g i c a l d e v o t i o n t o a c c u r a c y o n

m a t t e r s c o n c e r n i n g t h e w e a t h e r . I n s u c h a ca s e, a l t h o u g h J o h n i s, a d m i t t e d ly ,

a m o s t u n r e l i a b l e i n f o r m a n t o n m o s t m a t t e r s , w e c a n s a y t h a t h e w o u l d

n o t h a v e s a i d it w a s r a i n i n g u n l e s s i t w a s s o . T h i s is o n l y t o s a y t h a t t h e

r e f er r in g e x p r e s s io n s t o b e f o u n d i n ' R ' a n d ' P ' help to def ine the scope o ft h e i m p l i e d g e n e r a l i z a t i o n . R e c a l l , t h e i m p l i e d g e n e r a l i z a t i o n w a s a b o u t

s t a t e s o f a f f a i r s s imi lar t o ( t h e p a r t i c u l a r s ta t e s) R a n d P . S i m i l a r i n w h a t

r e s p e c t ? T h e s o r t o f r e f e r ri n g e x p r e s si o n s t o b e f o u n d w i t h i n ' R ' a n d ' P '

h e l p u s to a n s w e r th i s q u e s t io n . I n t h e c a s e o f J o h n a b o v e , t h e g e n e r a l

i m p l i c a t i o n i n v o l v e d , n o t a person ' s say ing someth ing ( u n d e r c i r c u m s t a n c e s

C) , n o t J o h n ' s s a y in g s o m e th in g ( u n d e r c i r c u m s t a n c e s C ) , b u t J o h n ' s s a y i n g

s o m e t h i n g a b o u t t h e w e a t h e r ( u n d e r c i r c u m s t a n c e s C ) .

2 . T h e P o s s ib i li t y o f M i s ta k e : T h e C o n n e c ti o n B e tw e e n (2 ) a n d (3) .

T a k i n g a c u e f r o m t h e f a c t t h a t (2 ) e x p re s se s so m e f o r m o f n e c e s s ar y r e -

l a t io n s h i p b e t w e e n R a n d P , I h a v e ( in m y o p e n i n g r e m a r k s ) e x p r e s s e d ( 2) a s:

G iv en R, -,~ ( ) ,-~ P (o r , a l t e r na t ive ly , ,,~ ( ) ( R . --~ P ) ) . I th in k the fu l l

j u s t i f ic a t i o n f o r e x p r e s s i n g ( 2 ) i n t h i s f a s h i o n l ie s i n t h e f a c t t h a t ( 2 ) a n d ( 3 )

a r e c o n t r a d i c t o r i e s , a n d s i n c e ( 3 ) m a y b e r e n d e r e d a s :

( 3 ) G i v e n R , ( ) ~ P ( o r , a l t e r n a t i v e l y , ( ) ( R . ,-~ P )

(2 ) m a y b e r e p re s e n t e d a s ' G iv e n R , ,,~ ( ) ,,~ P ' .

9





T o s e e t h a t t h i s i s s o , i t s h o u l d b e n o t i c e d t h a t i n d e n y i n g t h e c o n n e c t i o n

b e t w e e n R a n d P e x p r e s s e d b y (2 ) w e d o n o t c o m m i t o u r se l v e s t o a n y t h i n g

a s s t r o n g a s :

( 4) R w o u l d b e t h e c a s e e v e n t h o u g h n o t - P w e r e th e c a s e.

(4) i s the c o n t ra ry o f ( 2 ), n o t i t s c o n t r a d i c t o r y , s i nc e b o t h ( 2) a n d ( 4 ) m a y

t u r n o u t f a ls e , n F o r e x a m p l e , s u p p o s e S a s s e r t s ,

( 2g ) I w o u l d h a v e w o n t h e l o t t e r y i f I h a d b o u g h t t w o t i c k e t s ( i n s te a d

o f o n l y o n e ) .

W e m a y d e n y t h e t r u t h o f t hi s c o n t e n ti o n w i t h o u t c o m m i t t i n g o u r s e lv e s to

t h e t r u t h o f

( 4g ) Y o u w o u l d h a v e lo s t e v e n i f y o u h a d b o u g h t t w o t i c k et s .

A l l t h a t i s i n t e n d e d i n d e n y i n g (2 g ) i s t h a t t h e p u r c h a s e o f t w o t i c k e t s i s c o n -n e c t e d w i t h w i n n i n g in t h e a l le g e d m a n n e r , t h a t t h e p u r c h a s e o f tw o t i c k e t s

w o u l d h a v e a s s u r e d h i m o f w i n n i n g . I t s f a il in g t o b e c o n n e c t e d i n t h e

m a n n e r a l l e g e d i s , h o w e v e r , q u i t e c o n s i s t e n t w i t h h i s winn ing w i t h t w o t i c k e t s .W h a t w e c o m m i t o u r s e l v e s t o i n d e n y i n g ( 2 g ) i s :

( 3 g ) Y o u m i g h t h a v e l o s t e v e n w i t h t w o t i c k e t s .

(3 g ) a s s e r t s w h a t (2 g ) d e n i e s ; viz . t h a t e v e n w i t h t w o t i c k e t s it i s s t i l l a m a t t e r

o f c h a n c e , t h e p o s s i b i l i ty o f l o s i n g i s n o t e l im i n a t e d b y h o l d i n g t w o t i c k e ts

i n s t e a d o f o n e .

A s a m a t t e r o f c o m m o n p r a c t ic e , o f c ou r se , w e o ft e n e m p l o y s o m e t h i n g

s i m i l a r t o (4 ) i n d e n y i n g (2 ). T h i s i s u n d e r s t a n d a b l e e n o u g h s i n c e t h e t r u t h

o f ( 4~ d o e s e n t a i l t h e fa l si ty o f ( 2 ) . T h e p o i n t I a m d r i v i n g a t , h o w e v e r , is t h a t

w e n e e d n o t a f f i rm a n y t h i n g a s s t r o n g a s ( 4 ) i n d e n y i n g ( 2 ) ; a ll w e a r e r e q u i r e d

t o a f fi r m i s t h a t R a n d n o t - P m i g h t b o t h b e t h e ca s e o r t h a t , e v e n t h o u g h R

i s g i v e n , P m i g h t n o t b e th e ca s e. T h a t is t o s ay , t h e p r o p e r e x p r e s s io n f o r

t h e n e g a t i o n o f (2 ) is ( 3 ) ; a n d i f w e u n d e r s t a n d ( 3) a s a f f ir m i n g ' G i v e n R ,

( ) -~ P ' ( a l te r n a t i v e ly ( ) ( R . ,-~ P ) ) , t h e n w e a r e j u s ti f ie d i n r e p r e s e n t i n g

( 2 ) a s ' G i v e n R , N ( ) ~ p ' ( a l t e r n a t iv e l y , -,~ ( ) ( R . ,-~ P ) ) . I f s o m e o n e

s a ys , ' J a m e s w o u l d n o t h a v e c o m e w i t h o u t a n i n v i ta t io n ' , w e c a n d e n y t h is

w i t h o u t s u p p o s i n g t h a t J a m e s w o u l d h a v e c o m e w i t h o u t a n i n v it a ti o n .

F o r s u p p o s e w e k n o w t h a t i f J a m e s h a d n o t r e c ei ve d a n i n v it a ti o n , h e w o u l d

h a v e f l ip p e d a c o i n t o d e c id e w h e t h e r t o g o o r n o t . I n s u c h a c a s e , i t is n o t

t r u e t h a t h e w o u l d n o t h a v e c o m e w i t h o u t a n i n v i t a ti o n , b u t n e i t h e r is i t

t r u e t h a t h e w o u l d h a v e c o m e w i t h o u t a n i n v i ta t io n . T h e f a c t is t h a t h e

m i g h t h a v e c o m e ( d e p e n d i n g o n t h e o u t c o m e o f th e t o s s) w i t h o u t a n i n v i t a ti o n .

B e f o r e p r o c e e d i n g t h e r e is a n i m p o r t a n t a m b i g u i t y w h i ch m u s t b e e l i m in -

a te d . T h e r e is a u s e o f t h e w o r d ' m i g h t ' ( a n d r e la t ed m o d a l t e r m s ) w h i c h

g iv e s e x p r e ss i o n t o t h e s p e a k e r ' s e p is t e m i c s t a t e in r e l a t i o n t o s o m e s i t u a t io n .I t is a u s e o f th e w o r d ' m i g h t ' w h i c h i s n a t u r a l l y f o l l o w e d b y a p a r e n t h e t i c a l

' f o r a l l I k n o w ' . F o r e x a m p l e , i n sa y i n g , ' H e m i g h t w i n t h e e l e c t io n ' t h e

11 A point w hich Go od m an acknowledges in a footn ote: 'Literally a semifactual and thecorresponding counterfactual ar e not contradictories hu t contraries, an d b oth m ay befalse. ' F ac t, Fiction and Forecast, p. 32, note 2.

1 0




Conc lus ive Reasons

s p e a k e r i s m o s t n a t u r a l l y u n d e r s t o o d a s e x p r e s s i n g t h e f a c t t h a t h e d o e s n o t

k no W w h e t h e r h e w il l w i n t h e e l e c ti o n o r n o t , t h a t h e h a s n o ( o r t h e r e a r e n o )

v e r y c o n v i n c i n g g r o u n d s f o r s u p p o s i n g h e w i ll l os e . T h i s u s e o f t h e w o r d c a n

p r o p e r l y b e d e p l o y e d e v e n w h e n t h e s t a te o f a ff a ir s i n q u e s t i o n i s phys ica l lyo r logically i m p o s s i b l e . S , f o r i n st a n c e, m a y c o n c e d e t h e p r e m i s e s o f o u r

v a l id a r g u m e n t b u t , n o n e t h e l e s s , i g n o r a n t o f i ts v a li d i ty , i n si s t t h a t t h e c o n -

c lu s io n m i g h t ( f o r a l l h e k n o w s ) b e f a ls e e v e n t h o u g h t h e p r e m i s e s a r e t r u e .

C o n t r a s t e d w i t h t hi s e p is t e m i c u s e o f t h e m o d a l t e r m s is w h a t w e m i g h t

ca l l an object ive s e n se o f t h e se t e r m s , a s e n s e o f t h e t e r m ' c o u l d ' ( f o r e x a m p l e )

in w h ic h i f R e n t a il s P t h en , i n d e p e n d e n t o f w h a t S k n o w s a b o u t t h e l o g i ca l

r e la t io n s h i p b e t w e e n R a n d P , i t is f a ls e t o s a y t h a t R a n d n o t - P c o u l d ( o r

m i g h t ) b o t h b e t h e c a s e. M o r e o v e r , i f w e a c c e p t t h e r e s u lt s o f m o d e r n

p h y s ic s , t h e n i n th i s o b j e c t i v e s e n s e o f t h e t e r m S ' s s t a t e m e n t t h a t t h e r e a r eo b j e c ts w h i c h can t r a v e l f a s t e r t h a n t h e s p e e d o f l ig h t i s f a ls e , a n d i t i s fa l s e

e v e n t h o u g h , f o r a l l h e k n o w s , t h e r e a r e o b j e c t s w h i c h c a n . I n t h i s o b j e c t i v e

s en s e o n e i s m a k i n g a r e m a r k a b o u t t h e v a r i o u s p o s s ib i li ti e s f o r th e o c c u r -

r e n c e, o r j o i n t o c c u r r e n c e , o f e v e n t s o r t h e c o - e x i s t e n c e o f s ta t e s o f a f f a ir s ,

a n d in t h is s e n s e ig n o r a n c e o f w h a t is t h e c a se is n o g u a r a n t e e t h a t o n e ' s

s t at e m e n ts a b o u t w h a t m i g h t o r cou ld b e t h e c a s e a r e t r u e . T h e p o s s i b i li t ie s

m u s t a c t u a l ly b e a s o n e al le g es . W h e n S ( k n o w i n g t h a t J a m e s h a d a n i n -

v i ta t io n t o c o m e ) a s s e r ts t h a t J a m e s , b e i n g th e s o r t o f f e ll o w h e i s, m i g h t

( e v e n ) h a v e c o m e w i t h o u t a n i n v i t a t i o n , h e i s m a k i n g a r e m a r k a b o u t J a m e sa n d w h a t J a m e s is i nc li n ed t o d o o r c a p a b l e o f d o i n g . H e is o b v i o u s l y n o t

r e g is te r in g s o m e f a c t a b o u t h i s i g n o r a n c e o f w h e t h e r o r n o t J a m e s p o s s e s se s

a n i n v i t a t i o n .

T h e m o d a l t e r m a p p e a r i n g i n ( 3) is m e a n t t o b e u n d e r s t o o d in th e o b j e c t iv e

s e ns e . ( 3) i s m e a n t t o b e a s t a t e m e n t a b o u t t h e p o s s ib i l it ie s f o r t h e j o i n t

r e a li z a ti o n o f tw o s t at e s o f a ff a ir s ( R a n d n o t - P ) i n d e p e n d e n t o f w h a t t h e

s p e a k e r h a p p e n s t o k n o w a b o u t t h e a c t u a l r e a l iz a t i o n o f P ( R b e i n g g i ve n ) .

D r a w i n g f r o m o u r d i s c u s s i o n i n t h e p r e c e d i n g s e c t i o n , w e c a n s a y t h a t i f

( 2) i s t r u e , i f R w o u l d n o t b e t h e c a s e u n le s s P w e r e t h e c a s e , t h e n in thesecircumstances ( sp e c i f i e d e a r l i e r ) P i s a s t a t e o f a f f a i r s w h i c h i s n e c e s s a ry t o

t h e r e a l i z a t i o n o f R . H e n c e , i n t h e s e c i r c u m s t a n c e s i t i s f a ls e t o s a y t h a t

R a n d n o t - P m i g h t b o t h b e t h e c a s e o r th a t , g i v e n R , n o t - P m i g h t b e th e c a s e ,

a n d i t i s f a ls e w h e t h e r o r n o t a n y o n e a p p r e c i a t e s t h e f a c t t h a t i t is f al se .

W e h a v e h e r e a m o r e o r l es s par t icu lar i zed i m p o ss i b i l i t y ; ( 3 ) , a s w e l l a s (2 ) ,

is t i e d t o t h e c i r c u m s t a n c e s , C , s p e c i f ie d e a r li e r . N o t h i n g e ls e b u t ( a s t a t e

s u c h as ) P c o u l d h a v e b r o u g h t a b o u t ( a s t a t e s u c h a s) R in these c ircumstan ces .O f t en , o f c o u rs e , o u r s t a t e m e n t s a b o u t w h a t c o u l d b e t h e c a se , a b o u t w h a t is

p o s s ib l e , a r e b r o a d e r i n sc o p e . T h e y d o n o t r e s tr i c t t h e m s e l v e s t o t h ep a r t i c u l a r s e t o f c i r c u m s t a n c e s p r e v a i li n g o n s o m e s p e ci fi c o c c a s i o n . T h e y

a r e s t a t e m e n t s t o t h e e f fe c t t h a t , w h a t e v e r t h e c i r c u m s t a n c e s o n t h is o c c a s i o n

h a p p e n e d t o b e , t h e r e a r e ( n o n e t h e l e s s ) c i r c u m s t a n c e s i n w h i c h a s t a t e

r e l e v a n tl y s i m i l a r t o R is , o r m i g h t e a s i ly b e , b r o u g h t a b o u t w i t h o u t a s t a t e

r e l e v a n t ly s i m i l a r t o P. S m a y a d m i t , f o r e x a m p l e , t h a t t h e t h e r m o m e t e r

w o u l d n o t h a v e r e a d 9 8.6 u nl es s t h e c h il d 's t e m p e r a t u r e w a s n o r m a l - - h e n c e ,

11





c o n c e d e t h a t i t w o u l d b e f a l s e t o s a y t h a t i n t h e s e c i r c u m s t a n c e s ( g i v e n t h e

t h e r m o m e t e r r e a d in g ) th e c h il d m i g h t ( n o n e th e l e s s) h a v e a fe v e r . Y e t , h e

m a y g o o n t o i n s i s t t h a t o n e c a n g e t a n o r m a l r e a d i n g o n a t h e r m o m e t e r

w i t h a fe v e r is h c h i ld . O n e c a n d o s o w h e n o n e h a s a d e fe c t iv e t h e r m o m e t e r ,w h e n t h e c h i ld is s u c k i n g a n i c e c u b e , a n d s o o n . T h a t is , o n e c a n h a v e

R w i t h o u t P i n o t h e r c i r c u m s t a n c e s . T h e s e " g e n er a l' p o s s i b il i ti e s a re ,

h o w e v e r , q u i t e c o n s i s t e n t w i t h t h e ' p a r t i c u l a r i z e d " i m p o s s i b i l i t i e s e x p r e s s e d

b y ( 3 ). M o s t g e n u i n e i m p o s s i b i li t ie s c a n b e m a d e p o s s i b l e b y e n l a r g i n g t h ef r a m e o f r e f e r e n c e , b y r e la x i n g t h e c o n d i t i o n s t a c i tl y t a k e n a s f ix e d i n t h e

o r i g in a l s t a t e m e n t o f i m p o s s ib i li ty . I c a n ' t s w im t h e E n g l is h C h a n n e l ;

t h is d e s p it e t h e f a c t t h a t I c o u l d / f I h a d t r a i n e d s in c e a b o y , b e e n e n d o w e dw i t h t h e r e q u i s i t e e n d u r a n c e , e t c .

I f I m a y s u m m a r iz e t h e a r g u m e n t u p t o t hi s p o i n t in p r e p a r a t i o n f o r t h ef o l l o w i n g s e c t i o n : ( 1) e n t a il s (2 ) , i f S k n o w s t h a t P , a n d h e k n o w s t h i s o n t h e

b a s is ( s im p l y ) o f R , t h e n R w o u l d n o t b e t h e c a s e u n l e ss P w e r e th e c a s e .

F u r t h e r m o r e , ( 2 ) g iv e s e x p r e s s i o n t o a c 6 n n e c t i o n b e t w e e n R a n d P w h i c h

p e r m i t s u s t o s a y t h a t w h e n R i s g i v e n, in t h e k i n d o f c ir c u m s t a n c e s w h i c h

a c t u a l l y p r e v a i l e d o n t h e o c c a s i o n i n q u e s t i o n , t h e p o s s i b i l i t y o f n o t - P i s

e l i m i n a t e d . T h e s en s e o f t h e w o r d ' p o s s i b l e ' t h a t i s o p e r a t i v e h e r e is , I

s u b m i t , t h e s a m e s e n se o f t h is w o r d t h a t i s o p e r a t i n g i n o u r s t r o n g e s t s t a t e -

m e n t s a b o u t w h a t is p h y s i c a l l y p o s s i b l e ; t h e d i f f e re n c e b e t w e e n t h e p o s s i b i l it y

e x p r e s s e d i n (3 ) a n d o t h e r , a p p a r e n t l y s t r o n g e r , s t a t e m e n t s o f w h a t i s p o s s i b l ea n d i m p o s s i b l e i s s i m p l y a s h i f t i n t h e s e t o f c i r c u m s t a n c e s w h i c h i s t a k e n a s

f ix e d . T h e i m p o s s i b i l i ty e x p r e s s e d b y ( 3 ) i s a n i m p o s s i b i l i ty r e l a t i v e t o t h o s e

c i r c u m s t a n c e s , C , h e l d f i x e d i n ( 2 ) , a n d i t i s t h i s f a c t w h i c h m a k e s ( 3 ) t h e

c o n t r a d i c t o r y o f (2 ) a n d , h e n c e , w h i c h m a k e s it s n e g a t i o n a l o g i ca l c o n s e -q u e n c e o f ( 1 ) .

3 . C o n c l u s i v e R e a s o n s

L e t u s c al l R a c o n c l u s i v e r e a s o n f o r P i f a n d o n l y i f R w o u l d n o t b e t h e

c a s e u n l e s s P w e r e t h e c a se . 12 T h i s m a k e s l o g i c a ll y c o n c l u s i v e r e a s o n s( L C R ) a s u b c la s s o f c o n c l u s iv e r e a s o n s. C o n c l u s i v e r e a s o n s d e p e n d ,

s i m p l y , o n t h e t r u t h o f ( 2 ) ; l o g i c a l l y c o n c l u s i v e r e a s o n s r e q u i r e t h a t t h et r u t h o f (2 ) b e d e m o n s t r a b l e o n p u r e l y l o g i c al a n d d e f i n it i o n a l g r o u n d s .

W h e n t h e c o n d i t i o n a l is tr u e , b u t n o t l o g i c al ly t r u e , w e c a n s p e a k o f th e

c o n c l u s i v e r e a s o n s a s b e i n g e m p i r i c a l l y c o n c l u s i v e ( E C R ) .

O f c o u rs e , R m a y b e a c o n c l u s iv e r e a s o n f o r b e li e vi n g P w i t h o u t a n y o n eb e l ie v i n g P , m u c h l e ss h a v i n g R a s t h e i r r e a s o n f o r b e l ie v i n g . I sh a l l s a y ,

t h e r e f o r e , t h a t S h a s c o n c l u s iv e r e a s o n s , R , f o r b e l i e v in g P i f a n d o n l y i f :

(A) R i s a c o n c lu s iv e r e a s o n fo r P ( i. e. ( 2 ) i s t r u e ) ,( B ) S b e l ie v e s , w i t h o u t d o u b t , r e s e r v a t i o n , o r q u e s t i o n , t h a t P i s t h e

c a s e a n d h e b e li ev e s t h is o n t h e b a s is o f R ,

12 R eca ll footnote 5 concerning the particular wording o f (2); I intend those rem arks toapply to this d efinition o f 'conclusive reasons'.

1 2





( (2 ) ( i ) S k n o w s t h a t R i s t h e c a s e o r

( ii ) R i s s o m e e x p e r i m e n t a l s t a te o f S ( a b o u t w h i c h i t m a y n o t

m a k e s en s e t o s u p p o s e t h a t S k n o w s t h a t R i s t h e c a s e ; a t

l e a s t i t n o l o n g e r m a k e s m u c h s e ns e t o a s k h o w h e k n o w s ) .

W i th o n l y m i n o r e m b e l l i s h m e n t s , t o b e m e n t i o n e d i n a m o m e n t , I b e l ie v e

t h a t S ' s h a v i n g c o n c l u s i v e r e a s o n s f o r b e l i e v i n g P i s b o t h a n e c e s s a r y a n d a

s uf fi ci en t c o n d i t i o n f o r h i s k n o w i n g t h a t P is t h e c a s e . T h e a p p e a r a n c e o f

t he w o r d ' k n o w ' i n th i s c h a r a c t e r i z a t i o n ( in (C i ) ) d o e s n o t r e n d e r i t c i r c u l a r

a s a c h a r a c t e r i z a t i o n o f k n o w l e d g e s i n c e i t c a n b e e l i m i n a t e d b y a r e c u r s i v e

a p p l i c a t i o n o f t h e t h r e e c o n d i t i o n s u n t i l ( C i i ) is r e a c h e d .

I f S h a s c o n c l u s i v e r e a s o n s f o r b e l i e v i n g P , t h e n i t i s f a l s e t o s a y t h a t ,

g iv e n t h e s e g r o u n d s f o r b e li e f, a n d t h e c i r c u m s t a n c e s i n w h i c h t h e s e g r o u n d s

s e r v ed a s t h e b a s i s f o r h i s b e l i e f , S m i g h t b e m i s t a k e n a b o u t P . H a v i n g c o n -

c l u si v e r e a s o n s , a s I h a v e j u s t d e f i n e d i t , n o t o n l y i m p l i e s t h a t P i s t h e c a s e ,

i t n o t o n l y i m p l i e s t h a t S b e l i e v e s t h a t P i s t h e c a s e , b u t i t a l s o i m p l i e s t h a t ,

in t h e c i r c u m s t a n c e s i n w h i c h h e c a m e t o b e l i e v e t h a t P , h i s b a s is f o r b e -

l ie v i n g t h a t P w a s s u f f ic i e n tl y s e c u r e t o e l i m i n a t e t h e p o s s i b i l i t y o f h i s b e i n g

m i s t a k e n a b o u t P . T h i s g o e s a l o n g w a y t o w a r d c a p t u r i n g e v e r y t h i n g t h a t

p h i l o s o p h e r s h a v e t r a d i t i o n a l l y r e q u i r e d o f k n o w l e d g e . I n d e e d , i n c e r t a i n

r e sp e c ts i t g o e s b e y o n d i t i n r e q u i r i n g a s t r o n g e r c o n n e c t o n b e t w e e n o n e ' s

r e a s o n s o r g r o u n d s a n d w h a t o n e b e l i ev e s ( o n t h e b a s i s o f t h e s e r e a s o n s o r

g r o u n d s ) t h a n h a s n o r m a l l y b e e n d e m a n d e d b y t h o s e w i s h i n g t o p r e s e r v e o u r

o r d i n a r y k n o w l e d g e c l a i m s f r o m s c e p t ic a l c r i t i c i s m , la S i n ce , h o w e v e r , I

h a v e a l r e a d y a r g u e d f o r t h e n e c e s s i t y o f ( A ) , f o r R ' s b e i n g a c o n c l u s i v e

r e a s o n f o r P , I s h a l l c o n c e n t r a t e o n t h e q u e s t i o n o f w h e t h e r o r n o t S ' s h a v i n g

a c o n c l u s i v e r e a s o n f o r b e l i e v i n g P i s s u f f i c ie n t f o r h i s k n o w i n g t h a t P .

13 I t i s t h i s s t ro n g e r co n n ec t i o n w h i ch b l o ck s t h e s o r t o f co u n t e rex am p l e wh i ch can b eg en e ra t ed t o ju s t i fi ed - t ru e -b e l i e f an a l y s es o f k n o wl ed g e . G e t t i e r ' s ( an d L eh re r ' s )

ex am p l es , fo r i n s tan ce , a r e d i r ec t ed a t t h o s e an a l y s es wh i ch co n s t ru e k n o wl ed g e i nt e rm s o f a degree of jus t i f i ca t ion wh ich i s co m pat ib le wi th be ing jus t i f i ed in b e l iev ings o m e t h i n g fa l se (b o t h G e t t i e r an d L eh re r m en t i o n t h i s f ea t u re a t t h e b eg i n n in g o f t h e i rd iscussion). Th e coun terexam ples a re then con s t ruc ted by a l low ing S to be l ieve tha t P(which is false) with the appropriate degree o f justif ication, l e t t ing P en ta i l Q (which i st ru e ) , an d l e t t in g S b e li ev e t h a t Q o n t h e b as i s o f i ts lo g i ca l r e l a t i o n s h i p t o P . W e h av e ,then, a case where S t ru ly bel ieves that Q with the appropriate degree o f justif ication( th i s d eg ree o f j u s t if i ca t io n i s a l leg ed l y p re s e rv ed t h ro u g h t h e en t a i lm en t b e t ween P an dQ) , b u t a ca s e wh e re S d o es not know t h a t Q ( s in ce h i s m ean s o f a r r i v i n g a s i t w e re s oc lear ly defec tive). O n the p resen t ana lys i s , o f course , the requ i red conn ect ion be tweenS ' s ev i d en ce an d P i s st ro n g en o u g h t o preclude P ' s b e in g f a ls e . On e can n o t h av e con-clusive r ea s o n s fo r b e l i ev i n g s o m e t h i n g wh i ch is f al se . Hen ce , t h i s s o r t o f co u n t e r -ex am p l e can n o t b e g en e ra ted . Pa r t o f th e m o t i v a t i o n fo r t h e p re s en t an a ly s i s i s t h eco n v i c t io n ( s u p p o r t ed b y Ge t t ie r - l i k e ex am p l es ) t h a t k n o wl ed g e , i f i t em b o d i e s an ev i -d en t i a l r e l a t i o n a t a l l , m u s t e m b o d y a s t ro n g en o u g h o n e t o e l i m i n a t e t h e possibilityo f m i s t ak e . See E d m u n d G e t t i e r ' s ' I s Ju s t if i ed T ru e B e l i e f K n o w l ed g e? ' Analysis,2 3.6 , J u n e 1 9 6 3 an d Ke i t h L eh re r , 'Kn o wl ed g e , T ru t h an d E v i d en ce ' , Analysis, 25.5,A p r i l 1 96 5. I s h o u l d a l s o m en t i o n h e re t h a t t h e s e s am e s o r t s o f co n s i d e ra t i o n s s eem edto m ove B r ian Sk yrm s tow ard a s im i la r ana lys i s ; see espec ia l ly pp . 385-86 in h i s 'T heE x p l ic a ti on o f " X K n o w s T h a t P " ' The Journal o f Philosophy, June 22, 1967.

21 3




Fred Dretske

S e v e ra l p r e l i m i n a r y p o i n t s m u s t b e m e n t i o n e d b ri ef ly . I t m a y b e t h o u g h t

t h a t i n a r g u i n g f o r t h e i m p o s s i b il i ty o f m i s t a k e a s a n e c e s s a r y c o n d i t i o n f o rk n o w i n g t h a t P I h a ve be e n w a s t i n g m y ti m e . I t m a y b e th o u g h t t h a t i f S

k n o w s t h a t P , t h e n P cannot b e f a l s e s i n c e S ' s k n o w i n g t h a t P e n t a i l s P ;h e n c e , S cannot b e m i s t a k e n in b e l i e v in g t h a t P . I n a n s w e r t o th i s o b j e c t i o ni t s h o u l d b e p o i n t e d o u t t h a t t h e i m p o s s ib i l it y o f m i s t a k e w h i c h I h a v e b e e nt a l k i n g a b o u t i s a n i m p o s s i b i l i ty w h i c h a r i s e s i n v i r t u e o f a special connection

b e t w e e n S ' s r e a s o n s , R , a n d w h a t h e c o n s e q u e n t l y b e l ie v e s , P . I t is n o t t h et ri v ia l i m p o s s ib i li ty o f b e i n g w r o n g a b o u t s o m e t h i n g w h i c h ( b y h y p o t h e s i s )

y o u k n o w . W h e n p h i l o s o p h e r s c o n c e r n t h e m s e lv e s w i t h th e p o s s ib i l it y o fm i s t a k e i n p u t a t i v e c a se s o f k n o w l e d g e , t h e y a re n o t c o n c e r n e d w i t h t h ep o s s ib i li ty o f m i s t a k e w h i c h is t ri v i a ll y a v o i d a b l e b y s a y in g t h a t / f y o u d o

k n o w t h a t P, t h e n y o u c a n n o t b e m i s t a k e n a b o u t P . T h e y a r e c o n c e r n e d ,r a t h e r , w i t h t h a t p o s s i b i l i ty a s i t e x is t s i n r e l a t i o n t o o n e ' s e v i d e n c e o r g r o u n d sf o r b e l ie v i n g P , a n d that i s t h e p o s s i b i l i t y w i t h w h i c h ( 2 ) i s c o n c e r n e d .

T h e p o i n t m a y be p u t in a n o t h e r w a y . B o t h

I . R w o u l d n o t b e t h e c a s e u n l e ss P w e r e t h e c a se

R i s t h e c a s ea n d

I I . R ~ P (w h e n i t i s not t r u e t h a t R w o u l d n o t b e t h e c a s e u n le s s P )R

c o n s t i t u t e c o n c l u s i v e g r o u n d s , l o g i c a l ly c o n c l u s i v e g r o u n d s , f o r b e l ie v i n g P .

N e i t h e r s e t o f p r e m i s e s w o u l d b e t r u e u n l e ss P w e r e t r u e , a n d t h i s f a c t is i n

b o t h c a s es d e m o n s t r a b l e o n p u r e l y l o g ic a l a n d d e f in i ti o n a l g r o u n d s . B u t t h e

s i g n if i ca n t d if f e r e n c e b e t w e e n I a n d I I i s t h a t i n I , b u t not i n I I , t h e s e c o n d

p r e m i s e alone t u r n s o u t t o b e a conclusive r e a s o n (E C R ) . I f w e w e r e s e a r c h in g

f o r c o n c l u s i v e r e a s o n s t o b e l ie v e P , t h e n i n t h e s e c o n d c a s e w e w o u l d r e q u i r e

a s o u r r e a s o n s both premises, a n d t h i s w o u l d r e q u i r e t h a t w e k n e w t h a t b o t h

p r e m i s e s w e r e t r u e ( s ee c l a u s e ( C ) i n h a v i n g c o n c l u s i v e r e a s o n s ) . I n c a s e I ,

h o w e v e r , th e s e c o n d p r e m i s e a l o n e is a c o n c l u s i v e r e a s o n a n d , h e n c e , t o h a v ec o n c l u s i v e r e a s o n s i t i s r e q u i r e d only that we know that R is the case. W e

n e e d n o t ( a s i n c a s e I I ) k n o w t h a t t h e f i rs t p r e m i s e i s t r u e . A l l t h a t is r e -

q u i r e d i n c a s e I f o r R a l o n e t o b e a c o n c l u s i v e r e a s o n is t h a t t h e f i rs t p r e m i s eb e t r u e ; t h e r e is n o t h i n g t h a t r e q u i r e s S to k n o w t h a t t h e f ir s t p r e m i s e i s t r u e

i n o r d e r t o h a v e R a s h i s c o n c l u s i v e r e a s o n f o r b e l ie v i n g P . F o r i f t h e f i rs tp r e m i s e is t r u e ( r e g a r d l es s o f w h e t h e r S k n o w s i t is t r u e o r n o t ) t h e n ( 3 ) i s

f a l s e ; h e n c e , t h e p o s s i b i l i t y o f S ' s b e i n g m i s t a k e n a b o u t P h a s b e e n s u c c e s s -

f u ll y a v o i d e d - - a n d i t h a s b e e n s u c c e ss f u ll y a v o i d e d whether or not S knowsit has been avoided.

I n s p e a k i n g o f c o n c l u s i v e r e a s o n s I d o n o t w i s h t o s u g g e s t t h a t i n h a v i n g R

a s a c o n c l u s i v e r e a s o n S m u s t b e i n a p o s i t i o n t o give R a s h i s r e a s o n . Rm a y s i m p l y b e a c e r t a i n e x p e ri e n c e w h i c h S h a s u n d e r g o n e a n d , h a v i n g u n d e r -

g o n e t h i s e x p e r ie n c e , c o m e t o t h e b e l i e f t h a t P w a s t h e c a s e o n t h e b a si s o f

( a s a r e s u l t o f ) t h i s e x p e r i e n c e . H e m a y f i n d i t d i f fi c u lt , o r imp o s s ib l e , t og iv e v e r b a l e x p r es s io n t o R . H e m a y h av e f o r g o t t e n R . O r R m a y c o n s is t

1 4




Conclusive Reasons

in s o m e t h i n g ' s l o o k i n g a p a r t i c u l a r w a y t o h i m w h i c h h e f in d s d if f i cu l t t o

d e s c ri b e. S til l, i f t h e w a y th e t h i n g l o o k s t o S i s s u c h t h a t i t w o u l d n o t l o o k

t h a t w a y u n le s s i t h a d t h e p r o p e r t y Q , t h e n i t s l o o k i n g t h a t w a y t o S is a

c o n c l u si v e r e a s o n f o r S ' s b e l ie v i n g t h a t i t h a s t h e p r o p e r t y Q ; a n d i f Sb e l i e v e s t h a t i t i s Q on this basis, t h e n h e h a s , i n t h e w a y t h e t h i n g l o o k s t o

h i m , a c o n c l u s i v e r e a s o n f o r b e l i e v in g i t Q .

A l s o , t h e re a r e a n u m b e r o f t h in g s w h i c h p e o p l e c o m m o n l y p r o fe s s t o k n o w

( S a c r a m e n t o i s t h e c a p i t a l o f C a l i f o r n i a , t h e e a r t h is r o u g h l y s p h e r i c a l ) f o r

w h i c h t h e r e is n o d e f in i te p i e c e o f e v id e n c e , n o s in g l e s t a te o f a f f a ir s o r e a s i ly

s p e ci fi a bl e s e t o f s u c h s t a te s , w h i c h e v e n a p p r o x i m a t e s a c o n c l u s i v e r e a s o n .

I n s u c h c as e s, a l t h o u g h w e c a n c it e n o s in g le p ie c e o f d a t a w h i c h i s c l in c h i n g

a n d , h e n c e , a r e a t a lo s s f o r c o n c l u s i v e r e a s o n s w h e n a s k e d t o g i v e re a s o n s

( or w h e n a s k ed ' H o w d o y o u k n o w ? ' ) w e , n o n et he le s s , o f te n e n o u g h h a v ec o n c lu s iv e r e a s o n s i n a v a s t s p e c t r u m o f ex p e r ie n c e s w h i c h a r e t o o d i v e rs e

t o a d m i t o f c o n v e n i e n t c it a t i o n . C o u n t l e ss e x p e ri e n ce s c o n v e r g e , s o t o s p e a k ,

o n th e t r u t h o f a g iv e n p r o p o s i t i o n , a n d t h is v a r i e ty o f e x p e r ie n c e m a y b e

s u ch t h a t a l t h o u g h o n e may h a v e h a d a n y one o f th e s e e x p e r ie n c e s w i t h o u t

t he p r o p o s i t i o n i n q u e s t i o n b e i n g t r u e , o n e would not h a v e h a d a / / o f t h e m

u n le s s w h a t o n e c o n s e q u e n t l y b el ie v e s w a s t ru e . T h e f a ll ib i li ty o f s o u r c e A

a n d t h e f a ll ib i li ty o f s o u r c e B d o e s n o t a u t o m a t i c a l l y e n t a il t h a t w h e n A a n d

B agree a b o u t P ' s b e i n g t h e c a s e , t h a t , n o n e t h e l e s s , P m i g h t s ti ll b e f a ls e .

F o r i t m a y b e t h a t A a n d B would not b o t h h a v e i n d i c a t e d t h a t P w a s t h e c a s e

u n le s s P w a s t h e c a s e a l t h o u g h n e i t h e r A n o r B , t a k e n b y th e m s e l v e s , p r o v i d e

c o n c l u s iv e r e a s o n s f o r P . F o r e x a m p l e , a l t h o u g h a n y s in g le n e w s p a p e r

a c c o u n t m a y b e i n e r r o r o n a p a r t i c u l a r p o i n t , s e v e ra l i n d e p e n d e n t v e r s i o n s

( w ir e se rv ic e s, o f c o u r se , t e n d t o e l i m i n a te t h is i n d e p e n d e n c e ) m a y b e e n o u g h

t o sa y t h a t w e k n o w t h a t s o m e t h i n g is so on the basis of the newspaper accounts.

A l l o f t h e m w o u l d n o t h a v e b e e n i n s u c h c lo s e a g r e e m e n t u n le s s t h ei r a c c o u n t

w a s s u b s t a n t i a l l y c o r r e c t . 14

F i n al ly , I d o n o t w i sh t o s u g g es t b y m y u s e o f t h e w o r d ' r e a s o n ' t h a t w h e n

S h a s c o n c l u s i v e r e a s o n s f o r b e l i e v i n g P , S h a s reasoned h is w a y t o t h e c o n -

c l u si o n th a t P is t h e c a s e f r o m p r e m i s e s i n v o l v i n g R o r t h a t S h a s c o n s c i o u s l y

u s e d R a s a r e a s o n i n a r r i v i n g a t t h e b e l i e f t h a t P . I a m i n c l i n e d t o t h i n k

( b u t I s h a ll n o t n o w a r g u e it ) t h a t w h e n o n e k n o w s t h a t P , o n w h a t e v e r b a s is

t hi s m i g h t b e , l it tl e o r n o r e a s o n i n g is i n v o l v e d . I w o u l d p r e f e r t o d e s c r i b e

i t a s f o l lo w s : s o m e t i m e s a p e r s o n ' s c o n v i c t i o n t h a t P i s t h e c a s e c a n b e

t r a c e d t o a s t a te o f a f fa i rs ( o r c l u s t e r o f s i t u a t io n s ) w h i c h s a ti sf ie s t h e t h r e e

c o n d i t i o n s d e f i n in g t h e p o s s e s s i o n o f c o n c l u s i v e r e a s o n s . W h e n i t c a n b e s o

t ra c e d , t h e n h e k n o w s ; w h e n i t c a n n o t b e s o t ra c e d , t h e n w e s a y h e d o e s n o t

14 T he fa ct tha t all newspapers sometimes prin t things wh ich are false does no t m ean tha twe can not kn ow that something is t rue o n the basis o f a s ingle newspaper accou nt .Th e relevant quest ion to ask (as in the case of a perso n's test im ony --see sect ion 1) is n otwhether newspapers sometimes prin t false stories, n ot even whether this newspaper some-times prints fa lse stories, bu t whe ther this newspaperwould have printed this story if i t wereno t t rue. T he Midville Weekly Gazette's s tory about dope addic t ion on the campusm ay not correspond wi th the facts , bu t wo uld The Times have printed this s tory aboutthe President 's visit to M oscow if i t were no t true ?

1 5




Fred Dretske

k n o w a l t h o u g h h e m a y b e r i g h t a b o u t P ' s b e in g t h e ca se . O f c o u r se , his

b e l ie f m a y b e traceable t o s u c h a s o u r c e w i t h o u t o u r b e i n g a b l e t o t r a c e i t .

I n s u c h a c a s e w e a r e m i s t a k e n i n s a y i n g th a t h e d o e s n o t k n o w .

T u r n i n g n o w t o t h e q u e s t io n o f w h e t h e r h a v i n g c o n cl u si v e re a s o n s t ob e l ie v e , a s d e f in e d b y ( A ) - ( C ) , c o n s t i t u t e s a s u f f ic ie n t c o n d i t i o n f o r k n o w l e d g e ,

I s h a ll m e n t i o n a n d b r i e f ly r e s p o n d t o w h a t I c o n s i d e r t o b e t h e m o s t s e r i o u s

o b j e c t i o n s t o t h i s p r o p o s a l .

T h e r e is , f ir st , a t e n d e n c y t o c o n f l a t e k n o w i n g t h a t P w i th k n o w i n g t h a t o n e

k n o w s t h a t P . I f t h is is d o n e t h e n c o n d i t io n s ( A ) - ( C ) w i ll i m m e d i a t e l y a p p e a r

i n s u f f i c i e n t s i n c e t h e y d o n o t d e s c r i b e S a s k n o w i n g o r h a v i n g a n y b a s i s f o r

b e l i e v in g t h a t R , h i s b a s i s f o r b e l i e v i n g P , c o n s t i t u t e s a n a d e q u a t e b a s i s , m u c h

l es s a c o n c l u s i v e b a s i s , f o r b e l i e v in g P . E v e n i f o n e d o e s n o t g o t h is f a r t h e r e

is s ti ll a t e n d e n c y t o s a y t h a t i f S k n o w s t h a t P , t h e n S m u s t a t l e a s t believet h a t h e k n o w s t h a t P is t h e c a s e. I f o n e a d o p t s th i s v i e w t h e n , o n c e a g a in ,

c o n d i t i o n s ( A ) - ( C ) a p p e a r i n a d e q u a t e s in c e t h e y d o n o t d e s c r i b e ( n o r d o t h e y

e n t a il ) t h a t S b e l i e v e s h e k n o w s t h a t P is t h e c as e . I s e e n o r e a s o n , h o w e v e r ,

t o a c c e p t e i th e r o f t h e se c la im s . W e n a t u r a l l y e x p e c t o f o n e w h o k n o w s t h a t

P t h a t h e b e li e ve t h a t h e k n o w s , j u s t a s w e e x p e c t o f s o m e o n e w h o is r i d in g a

b i c y c l e t h a t h e b e l i e v e h e is ri d i n g o n e , b u t i n n e i t h e r c a s e i s th e b e l i e f a

necessary a c c o m p a n i m e n t . T h e c o n f u s i o n is p a r t i a l ly f o s t e r e d , I b e li e v e,

b y a f a i l u r e t o d i s t i n g u i s h b e t w e e n w h a t i s i m p l i e d i n k n o w i n g t h a t P , a n d

w h a t i s i m p l i e d ( i n s o m e s e n s e ) b y s o m e o n e ' s saying h e k n o w s t h a t P . C o n -s id e r , h o w e v e r , c a s e s in w h i c h w e f r e e l y a s c r i b e k n o w l e d g e t o a g e n t s i n w h i c h

i t s ee m s q u i t e i m p l a u s i b l e t o a s s i g n t h e l e v e l o f c o n c e p t u a l s o p h i s t i c a ti o n

r e q u i s i t e t o t h e i r b e l i e v i n g s o m e t h i n g a b o u t k n o w l e d g e , b e l i e v i n g s o m e t h i n g

a b o u t th e i r e p i s te m i c r e l a t io n t o th e s t a te o f a f fa i rs i n q u e s t io n . A d o g m a y

k n o w t h a t h i s m a s t e r i s i n t h e r o o m , a n d I ( a t l e a s t ) w a n t t o s a y t h a t h e c a n

k n o w t h i s i n a s t r a i g h t f o r w a r d s e n s e w i t h o u t ( n e c e s s a ri ly ) p o s s e s s i n g t h e

c o n c e p t u a l u n d e r s t a n d i n g w h i c h s e e m s t o b e r e q u ir e d t o s a y o f h i m t h a t h e

b e li ev e s h e k n o w s t h is , b e l ie v e s t h a t h e h a s g o o d r e a s o n s , o r b e l ie v e s anything

a b o u t h i s e p i s t e m i c r e l a t io n t o t h e f a c t t h a t h is m a s t e r i s in t h e r o o m . x5Y e t , i t s e e m s p e r f e c t l y n a t u r a l t o s a y o f a d o g t h a t i t k n o w s ( s o m e t i m e s ) w h e n

h is m a s t e r i s i n t h e r o o m . A n d t h is is n o t , l et m e a d d , s i m p l y a m a t t e r o f t h e

d o g ' s b e in g ri g h t a b o u t s o m e t h i n g . F o r i f w e k n e w th a t t h e d o g t h o u g h t h i s

m a s t e r w a s i n th e r o o m o n t h e b a s is , s a y , o f c e r t a i n s o u n d s a n d s m e l ls ( s o u n d s

a n d s m e l l s t h a t w e r e , g e n e r a l l y s p e a k i n g , a r e l i a b l e s i g n o f h is m a s t e r ) w h e n

t h e s e s o u n d s a n d s m e l ls w e r e t o t a l ly u n r e l a t e d t o h i s m a s t e r ' s p r e s e n c e in t h e

r o o m on this occasion, w e w o u l d n o t s a y t h e d o g k n e w e v e n if h e h a p p e n e d

t o b e r i g ht a b o u t his m a s t e r ' s b e i n g in t h e r o o m . I m a g i n e a bl in d d o g ' s

b e i n g ' t a k e n i n ' b y a t h i e f in h is m a s t e r ' s c l o th i n g w h i l e th e m a s t e r l ie s u n -c o n s c i o u s i n t h e c o r n e r . T h e d o g , t a k e n i n a s h e is b y th e t h ie f , c e r t a i n l y

t h i n k s h i s m a s t e r is in t h e r o o m , a n d h e is r i g h t ( a lt h o u g h , o f c o u r se , h e i s

15 This seems to be the essence of A rthur D anto 's argument (against H intikka) th a t ' Sknows that P ' does not entai l 'S knows that S knows that P ' in 'On Knowing that WeKnow' , Epistemology: New Essays in the Theory of Knowledge, Avrum Stroll (ed.),1967, pp . 4 9-51.

1 6




Conclusive Reasons

w r o n g a b o u t t h i s m a n ' s b e i n g h i s m a s t e r ) . B u t j u s t a s c l e a r l y t h e d o g d o e s n o t

k n oW t h a t h is m a s t e r i s i n t h e r o o m . W e r e q u i r e c o n c l u s i v e r e a s o n s e v e n

i n t h e c a se o f a n i m a l s . W o u l d t h e d o g h a v e s m e l l e d w h a t h e d i d , a n d h e a r d

w h a t h e d i d , i f h i s m a s t e r w a s n o t i n t h e r o o m ? I f h e wouM have, o r mighthave, t h e n h e d o e s n ' t k n o w . 16

F u r t h e r m o r e , c o n s i d e r a s c e p t i c w h o t a l k e d h i m s e l f i n t o b e l i e v i n g t h a t h is

g r o u n d s f o r b e l i e v i n g in a n e x t e r n a l w o r l d w e r e n o t s u f f ic i e n t l y g o o d t o t r u l y

s a y h e knew t h e r e w a s a n e x t e r n a l w o r l d a n d , h e n c e , n o l o n g e r b e l i e v e d ,

p o s i t i v e ly d i s b e l i e v e d , t h a t h e k n e w t h e r e w a s a n e x t e r n a l w o r l d . I t h i n k

t h a t a s l o n g a s h e c o n t i n u e d t o b e l i e v e ( w i t h o u t d o u b t , r e s e r v a t i o n o r q u e s -

t io n ) th a t t h e r e w a s a n e x t e r n a l w o r l d , a n d c o n t i n u e d t o b e l i e v e i t o n t h e

s a m e b a s i s a s w e d o , h e w o u l d k n o w t h e r e w a s a n e x t e r n a l w o r l d ( a s s u m i n g

h e r e t h a t we k n o w i t ) whatever h e h a p p e n e d t o b e l i e v e a b o u t w h a t h e k n e w . 17T h e r e m a r k s I h a v e j u s t m a d e a b o u t b e l i e v i n g t h a t o n e k n o w s a p p l y , a

fortiori, t o k n o w i n g t h a t o n e k n o w s . O n e q u a li f i e s f o r k n o w l e d g e w h e n o n e

h a s c o n c l u s i v e r e a s o n s f o r b e l i e v i n g ; o n e n e e d n o t , i n a d d i t i o n , k n o w t h a t

o n e h a s c o n c l u s i v e g r o u n d s . T o k n o w t h a t o n e h a s c o n c l u s i v e r e a s o n s ,

e m p i r i c a l ly c o n c l u s i v e r e a s o n s , m e a n s t h a t o n e k n o w s t h a t ( A ) is t r u e a n d

th is , i n t u r n , m e a n s t h a t o n e h a s l o g i c a l l y c o n c l u s i v e r e a s o n s ( se e c a s e I

a b o v e ) . K n o w i n g t h a t o n e k n o w s i s a f o r m o f i n n o c u l a t i o n a g a i n s t s c e p t i c a l

c h a l l e n g e s to t h e q u a l i t y o f o n e ' s e m p i r i c a l ly c o n c l u s i v e r e a s o n s ; o n e knows

16 R o b e r t S l e ig h h a s s u g g e st e d a n i n t e r e s ti n g m o d i f i c a t io n o f t h is c a s e - - o n e t h a t w o u l dappea r to cause d i f f icu l ty . Sup pose tha t the dog is t a k e n i n b y t h e t h i e f b u t , i n a d d i t i o n ,c i r c u m s t a n c e s a r e s u c h t h a t t h e t h i e f wouM not b e i n t h e r o o m unless t h e d o g ' s m a s t e rwas a l so the re . I t m ay be a b i t d i f f icu l t t o imag ine c i rcum s tances o f th i s so r t , bu t o the re x a m p l e s ( n o t i n v o l v i n g a n i m a l s a s t h e k n o w e r s ) c a n e a s il y b e m a n u f a c t u r e d ( C h i s h o l m ' se x a m p l e o f a m a n m i s t a k i n g a s h e e p d o g f o r a s h e e p i n a f ie l d w o r k s n i c e l y w h e n t h ef u r t h e r c o n d i t i o n i s a d d e d t h a t t h e d o g w o u l d n o t b e t h e r e u n l e ss th e r e w e r e s o m e s h e e pi n t h e f ie l d) . W i t h s u c h a m o d i f i c a t i o n it w o u l d s e e m t h a t t h e d o g h a s c o n c l u s i v er e a so n s f o r b e l i e v i n g h i s m a s t e r p r e s e n t s i n c e i t w o u l d n o t h a v e h e a r d a n d s m e l l e d w h a t

i t d i d u n l es s it s m a s t e r w a s p r e s en t . B u t d o e s t h e d o g k n o w t h a t i t s m a s t e r i s p r e s e n t ?I t h i n k i t n a t u r a l t o r e a d t h is s i t u a t io n i n s u c h a w a y t h a t t h e d o g b e l i e v es t h a t i t s m a s t e ri s i n t h e r o o m because i t m is t aken ly be l i eves tha t th i s m an ( the th ie f ) i s h i s ma s te r . I fr ead in th i s way , o f course , the re i s no d i f fi cu l ty s ince the d og ' s ba s i s fo r be l i ev ing tha th i s m a s t e r i s p r e s e n t is o b v i o u s l y d e f e c t i v e - - i t i s n o t t r u e , n o r d o e s t h e d o g k n o w ,t h a t t h is m a n i s h i s m a s t e r . I f , h o w e v e r , w e r e a d th i s c a s e i n su c h a w a y t h a t t h e d o gs i m p l y t a k e s t h e s o u n d s a n d s m e l l s a s a s i g n o f h i s m a s t e r ' s p r e s e n c e ( w i t h o u t m i s -i d e n t i f y i n g a n y o n e ) t h e n t h e d o g does h a v e c o n c l us i v e r e a so n s ( h e w o u l d n o t h a v es m e l l ed a n d h e a r d w h a t h e d i d u n l e ss h is m a s t e r w a s p r e s e n 0 b u t I s h o u l d w a n t t o s a ytha t in th i s ca se he knows t h a t h i s m a s t e r is p r e s e n t. I d o n o t t h i n k t h a t t h is i s a n e x -c e ss iv e ly s t r a i n e d i n t e r p r e ta t i o n . I t s e e m s t o m e q u i t e s im i l a r t o s i t u a t io n s i n w h i c h w ek n o w t h a t s o m e t h i n g i s s o o n t h e b a s i s o f s o m e i n d i c a t o r o r s i g n ( e . g . a n i n s t r u m e n tr e a d in g ) b u t a r e i g n o r a n t a s t o t h e m e c h a n i s m in virtue of which t h a t i n d i c a t o r o r s i g n is ar e l ia b l e ( c o n c lu s i v e) in d e x o f w h a t w e p u r p o r t t o k n o w .

17 E x a m p l e s s u c h a s t h is , a l o n g w i t h o t h e r m o r e s y s t em a t i c c o n s i d e r a t io n s , c o n v i n c e m et h a t n o t o n l y s h o u l d w e n o t r e q u i r e t h a t S b e li e v e h e h a s c o n c l u s i v e r e a s o n s i n o r d e r t ok n o w , b u t a l s o t h a t w e s h o u ld n o t r e q u i re t h a t h e n o t b e l i ev e h e d o e s n o t h a v e c o n -c l u si v e r e a s o n s . I f a p e r s o n ' s b e l i e v in g t h a t h e k n o w s is c o m p a t i b l e w i t h h i s n o t k n o w i n g ,w h y s h o u l d n ' t a p e r s o n ' s b e l i ev i n g t h a t h e d o e s n o t k n o w b e c o m p a t i b le w i t h h i sk n o w i n g ?

2 .

1 7




Fred Dretske

t h a t R w o u l d n o t b e t h e c a s e u n l e s s P w e r e t h e c a se . L a c k i n g s u c h i n n o c u -

l a t i o n , h o w e v e r , o n e s ti l l k n o w s . O n e is s i m p l y le ss p r e p a r e d t o d e f e n d

( j u s t i f y ) t h e claim t o k n o w l e d g e ; b u t i n ab i li ty t o j u s ti fy t h e t r u t h o f w h a t o n e

c l ai m s , is s e ld o m , i f e v e r, a r e f u t a t i o n o f th e t r u t h o f w h a t o n e c l a i m s , a n dt hi s a p p l i e s t o k n o w l e d g e c l a im s a s w e l l a s a n y o t h e r .

T h e r e i s a c e r ta i n t y p e o f c o u n t e r - e x a m p l e w h i c h e x p l o it s t hi s c o n f u s i o n ,

a n d I w o u l d l ik e t o m e n t i o n i t a t th i s p o i n t t o f u r t h e r c l a r if y th e i n t e n t o f

c o n d i t i o n s ( A ) - (C ) . S u p p o s e S , f o r a p e rf e c t ly s il ly r e a s o n , o r b y sh e e r

a c c i d e n t , c o m e s t o t h e t r u e b e l i e f t h a t ( a s t a te s u c h a s ) R is a c o n c l u s i v e

r e a s o n f o r b el ie v i n g t h a t ( a st a te s u c h a s ) P i s o r w a s t h e ca s e . H a p p e n i n g

u p o n a s ta t e s u c h a s R i n th e a p p r o p r i a t e c i r c u m s t a n c e s , t h e n , h e b e li ev e s th a t

P is t h e c a s e o n t h e b a s is o f R . D o e s n ' t h e n o w h a v e conclusive reasons f o r

b e l i e v in g P ? B u t i s n ' t i t e q u a l l y o b v i o u s t h a t h e d o e s not k n o w t h a t P is t h e

c a s e ? Y e s a n d n o . Y e s , h e d o e s h a v e c o n c lu s i v e r e a s o n s ( a s I h a v e d e fi n e d

t hi s) . N o , i t is n o t o b v i o u s t h a t h e d o e s n o t k n o w t h a t P is t h e c a se . I

b e li ev e t h a t t h is o b j e c t i o n t r a d e s o n t h e v e r y c o n f u s i o n w e h a v e j u s t d i s c u ss e d ;

t h a t i s, i t m i s t a k e n l y s u p p o s e s t h a t i f S d o e s n o t k n o w t h a t R is c o n c l u s i v e

f o r P ( h a s n o l e g i t i m a t e b a s is f o r b e l i ev i n g th is ), t h e n S d o e s n o t k n o w t h a t

P is t h e c a s e ( h a s n o l e g i ti m a t e b a s i s f o r b e l ie v i n g t h is ). O r , w h a t I t h i n k

a m o u n t s t o t h e v e r y s a m e t h i n g , i t f a l l a c io u s l y c o n c l u d e s t h a t S ( g i v en h is

b a s is f o r b e li e f) m i g h t b e w r o n g a b o u t P f r o m t h e f a c t t h a t S ( g iv e n h is b a s is

f o r be l i e f) m i g h t b e w r o n g a b o u t R ' s b e in g c o n c lu s i v e f o r P . O r , t o p u t i t i n

s ti ll a n o t h e r w a y , i t i n c o r r e c t l y s u p p o s e s t h a t i f i t is , e i t h e r w h o l l y o r i n p a r t ,

a c c i d e n t a l t h a t S is r i g h t a b o u t R ' s b e i n g c o n c l u s i v e f o r P , t h e n i t is a ls o ,

e i t h e r w h o l l y o r i n p a r t , a c c i d e n t a l t h a t h e is r i g h t a b o u t P ' s b e i n g t h e c a s e .

S u c h i n f e r e n c e s a r e f a l l a c i o u s a n d , I b e li ev e , t h e y a r e f a ll a c i o u s in th e s a m e

w a y a s t h e f o l lo w i n g t w o e x a m p l e s : ( a) C o n c l u d i n g t h a t i t w a s s h e e r l u c k

( c h a n c e ), a m e r e a c c i d e n t, t h a t d e c l a r e r m a d e h is b i d o f se v e n s p a d e s b e c a u s e

i t w a s s h e e r l u c k ( c h a n c e ) , a m e r e a c c i d e n t , t h a t h e w a s d e a l t t h i r t e e n s p a d e s ;

( b) C o n c l u d i n g t h a t t h e w i n d o w w a s b r o k e n a c c i de n t a ll y b e c a u s e t h e m a n

w h o t h r e w t h e b r ic k t h r o u g h i t c a m e b y t h e b e li e f t h a t b r i c k s b r e a k w i n d o w s

i n a n a c c i d e n t a l (s il ly , u n r e a s o n a b l e , o r w h a t h a v e y o u ) w a y .S o m e t i m e s t h e s ta g e is se t f o r a n o n - a c c i d e n t i n a p u r e l y a c c i d e n t a l w a y .

I n t h e a b o v e c a s e i t is a c c i d e n t a l th a t S k n o w s t h a t P o n t h e b a s is o f R , b u t

t h is d o e s n o t m a k e i t a c c i d e n t a l t h a t h e is r i g h t a b o u t P - - f o r h e b e li ev e s P o n

t h e b a si s o f R a n d R s i m p l y w o u l d n o t b e t h e c a se u n le s s P w e r e t h e c a se .

G i v e n R , i t is n o t a t al l a c c i d e n t a l th a t h e is r i g h t a b o u t P . W h a t is a c c i d e n t a l

is t h a t h e w a s c o r r e c t in b e l i e v in g t h a t R w a s a c o n c l u s i v e r e a s o n f o r P , b u t a ll

t hi s s h o w s is th a t h e d o e s n o t k n o w t h a t R is c o n c l u s i v e f o r P , d o e s n o t k n o w

t h a t h e k n o w s t h a t P . A n d w i t h th i s m u c h I a m i n fu l l a g r e e m e n t . 18

xs In speaking of 'accidentality" in this connection I have in mind Peter Unger's analysiso f knowledge in terms o f its not being a t al l accidental that the perso n is r ight (see his'A n Analys is of Factual K now ledge ' Journal of Philosophy, M arch 21, 1968). Th at is , Iwa nt to claim that an y S satisfying co ndi t ions (A)-(C) is a perso n o f who m i t is t rue tosay that i t i s not at al l accidental that he is r ight about P 's being the case, al though i tm ay he accidental that this is no accident (i t m ay be accidental tha t he has conclusivereasons, that he has reasons in virtue of which it is not at all accidental that he is fightabou t P).

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S c e p t i c a l a r g u m e n t s h a v e t r a d i t i o n a l l y r e l i e d o n t h e f a c t t h a t S , i n p u r -

p o r t in g t o k n o w t h a t P o n t h e b a s is o f R , w a s c o n s p i c u o u s l y u n a b l e t oj u s t if y t h e q u a l i t y o f h i s r e a s o n s , w a s h o p e l e s s l y i n c a p a b l e o f p r o v i d i n g

s a ti s fa c to r y d o c u m e n t a t i o n f o r th e t r u t h o f ( A ) . T h e c o n c l u s i o n f a ll a c io u s l yd r a w n f r o m t h i s w a s t h a t S d i d n o t k n o w t h a t P w a s t r u e ( s i m p l y ) o n t h eb a si s o f R . C l e a r l y , h o w e v e r , a l l t h a t f o l l o w s f r o m t h e f a c t t h a t S h a s l it tl e

o r n o g r o u n d s f o r t h i n k i n g ( A ) t r u e is t h a t h e l a c k s s a t is f a c to r y g r o u n d s f o r

t h in k i n g h e k n o w s t h a t P is t r u e . I t d o e s n o t f o l lo w t h a t h e d o e s n o t k n o w

t h a t P is t r u e . K n o w i n g t h a t P is t h e c as e o n t h e b a s i s o f R i n v o l v e s k n o w i n g

t h a t R i s t h e c a s e ( a n d b e l i e v in g P o n t h a t b a s is ) w h e n ( A ) i s t r u e . I t i s the

t r u t h o f ( A ) , n o t t h e f a c t t h a t o n e k n o w s i t t r u e, w h i c h m a k e s R c o n c l u si v e

f o r P .

T h e r e i s a n o t h e r r e s p e ct in w h i c h t r a d i t i o n a l s c e p ti ca l a rg u m e n t s h a v e b e e no n th e m a r k . O n e w a y o f e x p r e ss i n g m y a r g u m e n t i s t o s a y t h a t t h e f a m i l ia ra n d ( to s o m e ) e x t r e m e l y a n n o y i n g c h a l le n g e , ' C o u l d n ' t i t b e a n i ll u s io n

( fa k e , i m i t a t i o n , e t c .) ? ' o r ' I s n ' t i t p o s s ib l e t h a t y o u a r e d r e a m i n g ( h a l l u c i n a t -i n g , e t c . ) ? ' i s , i n a c e r t a i n i m p o r t a n t r e s p e c t , q u i t e p r o p e r a n d a p p r o p r i a t e

e v e n w h e n t h e r e i s n o s p e c i a l r e a s o n t o t h i n k y o u a r e d r e a m i n g , h a l lu c i n a t in g ,

c o n f r o n ti n g a f a k e , e t c . F o r o u r k n o w l e d g e c l a i m s d o e n t a i l t h a t t h e e v i -d e n c e o r g r o u n d s o n e h a s f o r b e l i e v i n g w o u l d n o t h a v e b e e n a v a i l a b l e i f

w h a t o n e c o n s e q u e n t l y b e li ev e s ( a n d c l ai m s t o k n o w ) w e r e fa l s e; h e n c e ,

t h e y d o e n t a i l t h a t , g i ve n o n e ' s e v i d e n c e o r g r o u n d s , i t i s f a l s e t h a t o n em i g h t b e m i s t a k e n a b o u t w h a t o n e p u r p o r t s t o k n o w . ( 1) d o e s e n t a il t h e

f a ls it y o f ( 3 ) ; h e n c e , ( 1) c a n b e s h o w n t o b e f a l s e n o t o n l y b y s h o w i n g t h a t

S is d r e a m i n g o r h a l l u c i n a t i n g o r w h a t e v e r , b u t a l s o b y s h o w i n g t h a t h e

m i g h t b e , t h a t h i s e x p e r i en c e o r i n f o r m a t i o n o n w h i c h h e b a s es h i s b e l i e f

t h a t P c a n b e h a d i n s u c h c i r c u m s t a n c e s a s t h e s e w i t h o u t P b e i n g t h e c a s e .

I t is n o t i n t h e p r o p r i e t y o r r e l e v a n c e o f t h e s e c h a ll e n g e s t h a t s c e p t ic i s m h a s

g o n e a w r y . O n t h e c o n t r a r y , t h e p e rs i s te n t a n d c o n t i n u i n g a p p e a l o f s c ep t i-

c i s m l i e s i n a f a i l u r e t o c o me to g r ip s w i th t h i s c h a l l e n g e , i n a r e fu s a l t o

a c k n o w l e d g e i t s l e g i t i m a c y a n d , h e n c e , a n s w e r i t . I t s i m p l y w i l l n o t d o t oi n si st t h a t i n c o n c e r n i n g h i m s e l f w i t h t h e p o s s i b i l i ty o f m i s t a k e a s c e p t i c iss e tt in g ar t if i c ia l l y h i g h s t a n d a r d s f o r k n o w l e d g e a n d , t h e r e f o r e , m a y b e

i g n o r e d w h e n c o n s i d e r i n g o r d i n a r y k n o w l e d g e c la im s . ( 1 ) d o e s im p l y t h a t( 3) is f a ls e , a n d i t s e em s t o m e q u i t e a l e g i ti m a t e l i n e o f a r g u m e n t f o r t h e

s c e pt ic t o i n s is t t h a t i f ( 3) i s t r u e , i f y o u m i g h t b e d r e a m i n g o r w h a t e v e r ,

t h e n (1 ) is f a l s e - - y o u d o n o t k n o w , o n t h e b a s i s o f y o u r p r e s e n t v is u a l,

a u d i t o r y , et c . e x p e ri e n ce s , w h a t y o u p u r p o r t t o k n o w .

I t h i n k t h e r e a r e s e v e r al c o n f u s i o n s t o b e f o u n d i n t r a d i t i o n a l s c e p t i c is m ,

b u t o n e o f t h e m is n o t t h a t o f i n si s ti n g t h a t t o k n o w t h a t P o n t h e b a s is o f R ,R m u s t s o m e h o w p r e c l u d e t h e p o s s i b i li t y o f n o t - P . T h e c o n f u s i o n s li e e ls e -

w h e r e. I f o n e i n t e rp r e t s t h e ' m i g h t ' ( o r 'c o u l d ' ) o f ( 3) t o o n a r r o w l y (a s

s i m p l y ' l o g i c a l ly p o s s ib l e ' ) t h e n , o f c o u r s e , ( 3 ) w i ll , in a l m o s t a l l i n t e r e s ti n g

c a se s , t u r n o u t t r u e a n d ( t h e r e f o r e ) ( 1 ) f a ls e . E v e n i f o n e l i b e ra l iz e s t h e

i n t e r p r e t a t i o n o f ( 3 ), a n d t h i n k s o f i t as r e p r e s e n t in g s o m e f o r m o f p h y si c a l

i m p o s s i b i l it y a s I h a v e , t h e r e i s s ti ll t h e t e n d e n c y t o t h i n k o f th i s p h y s i c a l

1 9





i m p o s s i b i l i ty in i t s m o s t g e n e r a l s e n s e , a s t h e i m p o s s i b i l it y o f v i o l a t i n g s o m e

n a t u r a l l a w w h i c h h o l d s i n a l l c i r c u m s t a n c e s a n d n o t , a s I h a v e a r g u e d , t h e

i m p o s s i b il it y o f h a v i n g R w i t h n o t - P i n t h e p a r t ic u l a r c i r c u m s t a n c e s w h i c h i n

f a c t p r e v a i l o n t h e o c c a s i o n i n q u e s t i o n . T h e m o s t s u b tl e c o n f u s i o n , h o w -e v er , is t h e o n e m e n t i o n e d i n t he p r e c e d i n g p a r a g r a p h s - - t h e f a ll a cy o f

s u p p o s i n g t h a t i n k n o w i n g t h a t P w e m u s t s o m e h o w b e a b le t o j u st if y th e

f a c t t h a t w e k n o w t h a t P . D o u b t l e s s w e s h o u ld h a v e s o m e j u s ti f ic a t io n f o r

( 1 ) i f w e a s s e r t i t, b u t o u r l a c k o f s u c h a j u s t i f ic a t i o n r e fl e ct s, n o t o n t h e t r u t h

o f w h a t w e h a v e s a i d , b u t o n t h e p r o p r i e t y o f o u r s a y in g i t. W h a t w o u l d sh o w

t h a t w e d i d n o t k n o w t h a t P o n t h e b a s i s o f R is t h e t r u t h o f (3 ), n o t o u r

i n c a p a c i t y t o s h o w i t f a l s e ( b y s h o w i n g ( 2) t r u e f o r i n s ta n c e ) . F o r i f ( 2 ) i s

t r u e , t h e n , i n a n s w e r t o t h e s c e p t ic ' s q u e s t io n , ' C o u l d n ' t y o u b e h a l l u c in a t i n g ? '

o r ' M i g h t i t n o t b e a f a k e o r i m i t a t i o n o f so m e s o r t ? ' t h e c o r r e c t re s p o n se ,

w h e t h e r o r n o t w e k n o w i t c o r r e c t , w h e t h e r o r n o t w e c a n s h o w i t c o r r e c t

i s ' N o ! '

S ti ll, e v e n i f o n e s h o u l d a c c e p t t h e a r g u m e n t s u p t o t h i s p o i n t , t h e r e a r e

g e n u i n e d i f f ic u l ti e s w i t h t a k i n g a s a s u f fi c ie n t c o n d i t i o n f o r k n o w l e d g e , t h e

p o s s e s s i o n o f c o n c l u s i v e r e a s o n s t o b e li e v e . I s h a ll n o t t r y to a b s o r b t h e s e

d i ff ic u lt ie s i n th i s p a p e r ; I h a v e t r i e d t o d o s o w i t h r e s p e c t t o a m o r e r e s t r i c t e d

s e t o f c a se s ( v is u a l p e r c e p t i o n ) i n a n o t h e r p l a c e . 19 W h e t h e r t h e s e c o m p l i c a -

t i o n s c a n b e h a n d l e d i n t h e m u c h m o r e g e n e r a l ty p e o f s i t u a ti o n I h a v e b e e n

d i s c u s s in g I l e a v e o p e n - - - o n l y s u g g e s t i n g t h e l in e s a l o n g w h i c h I t h i n k t h e y

c a n b e sa t is f a c to r i ly h a n d l e d . T h e t w o e x a m p l e s I p r e s e n t d o n o t a f f e c t

m y a r g u m e n t t h a t t h e p o s s e s s i o n o f c o n cl u s iv e r e a s o n s is a n e c e s s a r y c o n -

d i t io n f o r k n o w l e d g e .

S , u p o n i n s p e c t i n g a n i m m e r s e d c h e m i c a l i n d i c a t o r , d e c l a r e s t h a t t h e

s o l u t i o n i n w h i c h i t i s i m m e r s e d is a b a s e . H e b e l ie v e s ( c o r r e c t l y ) t h a t t h e

i n d i c a t o r is t h e s o r t w h i c h t u r n s f r o m y e l lo w to b l u e o n l y w h e n i m m e r s e d

in a ba s e. T h e i n d i c a to r is T h y m o l B lu e a n d w o u l d n o t h a v e t u r n e d f r o m

y e l l o w t o b l u e ( i n t h e s e c o n d i t i o n s ) u n l e s s th e s o l u t i o n w e r e a b a s e . T h e

f o l l o w i n g t h r e e c o n d i t i o n s a r e s a t i s f i e d :

( A ' ) T h e i n d i c a t o r ' s c h a n g e i n c o l o u r ( y e l lo w t o b l u e) is a c o n c lu s i v e

r e a s o n f o r b e l i e v in g t h a t t h e s o l u t i o n i s a b a s e .

( B ' ) S b el ie v e s t h a t t h e s o l u t i o n i s a b a s e a n d h e b e l ie v e s t h is o n t h e

b a s i s o f th e i n d i c a t o r ' s c h a n g e i n c o l o u r .

( C ' ) S k n o w s t h a t t h e in d i c a t o r c h a n g e d f r o m y e l l o w t o b l u e ( h e s a wi t c h a n g e - - s a w t h a t i t c h a n g e d ) .

I h a v e s a i d t h a t t h e s e t h r e e c o n d i ti o n s w e r e s u ff ic ie n t f o r k n o w l e d g e . D o e s

S k n o w t h a t th e s o l u t io n is a b a s e ? B e f o r e a n s w e r i n g t h is q u e s t io n t h e

r e a d e r s h o u l d b e i n f o r m e d t h a t t h e r e is a n o t h e r c h e m i c a l in d i c at o r, B r o m o -p h e n a l B l u e , w h i c h a l s o t u r n s f r o m y e l l o w t o b l u e b u t o n l y w h e n i m m e r s e d

i n a n a c i d . S , h o w e v e r , i s q u i te u n a w a r e o f t h e e x is te n c e o f o t h e r s u c h

i n d i c at o r s . H e m e r e l y a s s u m e s t h a t a y e ll o w i n d i c a t o r t u r n i n g b l u e is a

p o s i t iv e t e s t f o r a b a se . S ' s i g n o r a n c e o n t h i s p o i n t d o e s n o t a l t e r t h e f a c t

la Seeing a nd K nowing (Chicago; 1969), Ch apter II I.

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Conclusive Reasons

t h a t t h e a b o v e t h r e e c o n d i t i o n s a r e sa ti sf ie d . Y e t , d e s p i t e t h e s a t i s f a c t i o n

o f t h es e c o n d i t i o n s , I fi n d i t ( in s o m e c a s es ) m o s t i m p l a u s i b l e t o s a y h e k n o w s

t h a t t h e s o lu t i o n is a b a s e. W h e t h e r h e k n o w s o r n o t d e p e n d s i n a c ru c i a l

w a y o n o u r u n d e r s t a n d i n g o f c o n d i t i o n ( B ') a b o v e . T h e in d i c a t o r ' s c h a n g ei n c o l o u r , a l t h o u g h i t is a c o n c l u s i v e r e a s o n , h a s i ts c o n c l u s i v e n e s s , s o t o

s p e ak , r e s tr i c te d i n s c o p e t o t h e r a n g e o f c as e s i n w h i c h T h y m o l B l u e is th e

i n d i c a t o r ( o r, i f t h is l a b o r a t o r y o n l y u s e s T h y m o l B l u e , i n w h i c h t h e i n -

d i c a t o r is fro m t h is l a b o r a t o r y o r o f t h e s o r t u s e d i n t h is l a b o r a t o r y ) . W h a t

is a c o n c l u s i v e r e a s o n f o r b e l ie v i n g t h e s o l u t i o n t o b e a b a s e is t h a t a Thymol

Blue i n d i c a to r ( o r a n i n d i c a t o r f r o m t h i s l a b o r a t o r y ) c h a n g e d f r o m y e l lo w to

b l ue w h e n i m m e r s e d i n i t , not s i m p l y t h a t an ( u n s p e c i f i e d ) c h e m i c a l i n d i c a t o r

c h a n g e d f r o m y e l l o w t o b lu e . T h e f a c t t h a t this i n d i c a t o r happens to be

T h y m o l B lu e is w h a t a c c o u n t s f o r th e t r u th o f ( A ' ) a b o v e . S in ce , h o w e v e r ,

i t is a T h y m o l B l u e in d i c a t o r ' s ( o r s o m e o t h e r a p p r o p r i a t e l y s p ec if ie d in -

d i c a t o r 's ) c o l o u r t r a n s f o r m a t i o n w h i c h is c o n c l u s iv e , w e m u s t ( s ee c o n d i t i o n

( B ' )) r e q u i r e t h a t S ' s b a s i s f o r b e l ie v i n g t h e s o l u t i o n a b a s e b e t h a t a Thymol

Blue indicator ( o r such-and-such indicator) c h a n g e d f r o m y e l lo w t o b lu e . H e

n e e d n o t , o n c e a g a i n , k n o w t h a t a T h y m o l B l u e 's c o l o u r t r a n s f o r m a t i o n ( o r

s u c h - a n d - s u c h i n d i c a t o r ' s t r a n s f o r m a t i o n ) is conclusive, b u t h e m u s t b e

e x p l o i t i n g t h o s e t h i n g s a b o u t t h e i n d i c a t o r ' s t r a n s f o r m a t i o n in virtue of

which it is conclusive. I n s o m e c a s e s a n A ' s b e i n g B is a c o n c l u s i v e r e a s o n f o r

b e l ie v i n g P o n l y i n v i r t u e o f t h e f a c t t h a t i t is , i n p a r t i c u l a r , a n A ( o r , s a y ,

s o m e t h i n g w h i c h i s Q ) w h i c h i s B ; i n s u c h c a s e s w e m u s t u n d e r s t a n d c o n -

d i t io n ( B ) a s r e q u i r i n g t h a t S ' s b a s is f o r b e l ie v i n g P i n c lu d e , n o t o n l y t h e

f a c t t h a t t h is ( s o m e t h i n g o r o t h e r ) i s B , b u t a l so t h a t t h is s o m e t h i n g o r o t h e r

is , i n p a r t i c u l a r , an A ( o r s o m e t h i n g w h i c h is Q ) . A n d t h is r e q u ir e s o f u s i n

a d d i t i o n t h a t w e u n d e r s t a n d c o n d i t i o n ( C ) a b o v e i n s u ch a w a y t h a t S n o t

o n l y k n o w t h a t R is t h e c as e , k n o w ( le t u s s a y ) t h a t A is B , b u t a l s o k n o w t h a t

i t i s , i n p a r t i c u l a r , an A w h i c h i s B . ~°

O n e f u r t h e r e x a m p l e t o i l l u s tr a t e a d i s t i n c t, b u t c l o s e l y r e l a t e d , d i f f ic u l ty .

S u p p o s e K is b e h a v i n g i n su c h a w a y t h a t i t is t r u e t o s a y th a t h e w o u l d n o t

b e b e h a v i n g in t h a t w a y u n le s s he w a s n e r v o u s . S u p p o s e S p u r p o r t s t o k n o w

t h a t K is n e r v o u s a n d w h e n a s k e d h o w h e k n o w s t hi s, r e p li es b y s a y in g ,

s0 This typ e of restriction is required fo r the sort o f example discussed in m y article 'Re as on sand Consequences' , Analysis, Apri l, 1968. In this art icle I argue d that on e could knowtha t the A is B (e.g. the widow was limping) while having li t t le, if any, justificationfo r believing tha t i t was, in particular, a widow w ho was limping (hence, on e could kn owthat the widow was l imping without knowing t ha t it was a widow who was l imping).Since, however, the statement 'T he w idow is l imping' implies 'Th er e is (or i t is) a widoww ho is l imping' , I to ok this as show ing that S cart kno w tha t P, kn ow th at P entails Q ,and ye t no t know th at Q. O n the present analysis o f conclusive reasons, of course, Pis a conclusive reaso n fo r Q (since P entails Q ) and any one wh o bel ieved Q o n the basis o fP shou ld (on this analysis) kn ow th at Q. Th e restriction being discussed in the textblocks this result by requiring S to know those things in particular about P which makesi t conclusive for Q. In this example S m ust kn ow that it is a widoww ho is l imping sinceit is this aspect o f his conclusive reas on (the wid ow is l imping) in virtue o f wh ich itfunct ions as a conclusive reason for bel ieving that there is a w idow who is l imping. Iam indebted to B ruce Freed fo r clari ficat ion on this po int .

2 1





' F r o m t h e w a y h e is b e h a v i n g . ' O n c e a ga i n, o u r t h r e e c o n d i t i o n s a r e sa ti s-

f ie d , o r c a n e a s i l y b e a s s u m e d t o b e s at is fi ed . Y e t , i f w e s u p p o s e t h a t t h e

d i st in c t iv e t h in g a b o u t K ' s b e h a v i o u r i s t h a t h e is d o i n g B 1 whi le p e r f o r m i n g

B 2, t h e n i f S is r e ly i n g o n B t ( o r B 2) a l o n e , w e s h o u l d n o t s a y t h a t h e k n o w st h a t K i s n e r v o u s . I t is q u i t e t r u e t h a t t h e b a si s f o r S ' s b e l i e f ( t h a t K is

n e r v o u s ) is K ' s b e h a v i o u r , a n d i n t h i s ( r e l a ti v e l y u n s p e c i f ie d ) se n s e w e m i g h t

s a y t h a t S is r e ly i n g o n t h e s i g n i f ic a n t a s p e c t s o f t h e s i t u a t i o n , b u t t h e f a c t

i s t h a t t h e c r u c i a l a s p e c t s (t h o s e a s p e c ts w h i c h m a k e K ' s b e h a v i o u r c o n c lu s i v e )

a r e m o r e s p ec if ic t h a n t h o s e o n w h i c h S is r el y in g in p u r p o r t i n g t o k n o w .

W e m u s t i n si s t, t h e r e f o r e , t h a t S ' s b as i s f o r b e l ie v i n g P b e as speci f ic in

r e g a r d t o t h e r e l e v a n t as p e c t s o f R a s i s n e c e s s a r y t o c a p t u r e t h e d i s t in c t iv e

( i . e . c o n c lu s iv e , t h o se f i g u r in g e s se n t i a l l y i n t h e s a t i s f a c t io n o f ( 2 ) ) f e a tu r e s

o f t h e s i t u a t i o n .I t h i n k b o t h o f th e a b o v e q u a l if i ca t io n s c a n b e s u m m a r i z e d b y s a y in g t h a t

w h e n o n e h a s c o n c l u s i v e r e a s o n s , t h e n t h i s is s uf f ic i en t f o r k n o w i n g t h a t P i s

t h e c a s e w h e n t h o s e r e a s o n s are pro per ly spec if ic , b o t h w i th r e g a r d t o wh a t i t i st h a t d i s p la y s t h e p a r t i c u l a r f e a t u r e s o n w h i c h o n e r el ie s a n d o n t h e p a r t ic u l a r

f e a t u r e s t h e m s e l v e s . A c o m p l e t e s t a t e m e n t o f t h e s e r e s t r i c ti o n s is , h o w e v e r ,

f a r b e y o n d th e s c o p e o f th i s p a p e r . S u ff ic e i t t o s a y t h a t t h e p o s s e s s i o n o f

c o n c l u s i v e r e a s o n s f o r b e li e v in g is a n e c e s s a r y c o n d i t i o n f o r k n o w l e d g e a n d ,

p ro p e r ly q u a l i f i e d a lo n g th e l i n e s su g g e s t e d h e re , a l so ( I t h in k ) su f f i c i e n t .

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