SECT. 8.] Probability before and after the event. 285 



confidence about his veracity in matters into which he had 

 duly enquired), it would be because we thought that in his 

 case, as in ours, it was equivalent to a guess, and nothing 

 more. So with the event when past, the fact of its being- 

 past makes no difference whatever; until the credible wit 

 ness informs us of what he knows to have occurred, we 

 should doubt it if it happened to come into our minds, just 

 as much as if it were future. 



The distinction, therefore, between probability before the 

 event and probability after the event seems to resolve itself 

 simply into this ; before the event we often have no better 

 means of information than to appeal to statistics in some 

 form or other, and so to guess amongst the various possible 

 alternatives ; after the event the guess may most commonly 

 be improved or superseded by appeal to specific evidence, 

 in the shape of testimony or observation. Hence, naturally, 

 our estimate in the latter case is commonly of much more 

 value. But if these characteristics were anyhow inverted ; 

 if, that is, we were to confine ourselves to guessing about the 

 past, and if we could find any additional evidence about the 

 future, the respective values of the different estimates would 

 also be inverted. The difference between these values has 

 no necessary connection with time, but depends entirely 

 upon the different grounds upon which our conception or 

 conjecture about the event in question rests. 



8. The following imaginary example will serve to 

 bring out the point indicated above. Conceive a people with 

 very short memories, and who preserved no kind of record to 

 perpetuate their hold upon the events which happened 

 amongst them 1 . The whole region of the past would then be 



1 According to Dante, something cardinals and others whom he there 

 resembling this prevailed amongst meets are able to give information 

 the occupants of the Inferno. The about many events which were yet 



