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



of almost any witness is in most cases vastly better than 

 a mere guess 1 . We may in both cases alike speak of the 

 event if we will ; in fact, as was admitted in the last 

 chapter, common language will not readily lend itself to any 

 other way of speaking. But it should be clearly under 

 stood that, phrase it how we will, what is really present to 

 the man s mind, and what is to have its probable value 

 assigned to it, is the conception of an event, in the sense in 

 which that expression has already been explained. And 

 surely no two conceptions can have a much more important 

 distinction put between them than that which is involved in 

 supposing one to rest on a mere guess, and the other on the 

 report of a witness. Precisely the same remarks apply to 

 the example given by Mill. Before A. B. s death our 

 opinion upon the subject was nothing but a guess of our 

 own founded upon life statistics ; after his death it was 

 founded upon the evidence of some one who presumably 

 had tolerable opportunities of knowing what the facts really 

 were. 



7. That the distinction before us has no essential con 

 nection whatever with time is indeed obvious on a moment s 

 consideration. Conceive for a moment that some one had 

 opportunities of knowing whether A. B. would die or not. 

 If he told us that A. B. would die to-morrow, we should in 

 that case be just as ready to believe him as when he tells us 

 that A. B. has died. If we continued to feel any doubt 

 about the statement (supposing always that we had full 



1 In the extreme case of the wit- again in Chapter xvn. It may be 

 ness himself merely guessing, or remarked that there are several sub- 

 being as untrustworthy as if he tleties here which cannot be ade- 

 merely guessed, the two stones will quately noticed without some previ- 

 of course stand on precisely the same ous investigation into the question 

 footing. This case will be noticed of the credibility of witnesses. 



