286 Probability before and after the event. [CHAP. xn. 



to them what much of the future is to us ; viz. a region of 

 guesses and conjectures, one in reference to which they 

 could only judge upon general considerations of probability, 

 rather than by direct and specific evidence. But conceive 

 also that they had amongst them a race of prophets who 

 could succeed in foretelling the future with as near an 

 approach to accuracy and trustworthiness as our various 

 histories, and biographies, and recollections, can attain in 

 respect to the past. The present and usual functions of 

 direct evidence or testimony, and of probability, would then 

 be simply inverted ; and so in consequence would the pre 

 sent accidental characteristics of improbability before and 

 after the event. It would then be the latter which would 

 by comparison be regarded as not always a ground of dis 

 belief, whereas in the case of the former we should then 

 have it maintained that it always was so. 



9. The origin of the mistake just discussed is worth 

 enquiring into. I take it to be as follows. It is often the 

 case, as above remarked, when we are speculating about 

 a future event, and almost always the case when that future 

 event is taken from a game of chance, that all persons are in 

 precisely the same condition of ignorance in respect to it. 

 The limit of available information is confined to statistics, 

 and amounts to the knowledge that the unknown event 

 must assume some one of various alternative forms. The 

 conjecture, therefore, of any one man about it is as valuable 

 as that of any other. But in regard to the past the case is 

 very different. Here we are not in the habit of relying 

 upon statistical information. Hence the conjectures of dif 

 ferent men are of extremely different values ; in the case of 

 many they amount to what we call positive knowledge. 



to happen upon earth, but they had actually had happened, 

 to ask it for many events which 



