408 Credibility of Extraordinary Stories. [CHAP. xvn. 



ticular average having been assigned, is no reason for our 

 being forced invariably to adhere to it, even in those cases 

 in which our most natural and appropriate ground of judg 

 ment is found in an appeal to statistics and averages. 

 The general average may constantly have to be corrected 

 in order to meet more accurately the circumstances of par 

 ticular cases. In statistics of mortality, for instance, instead 

 of resorting to the wider tables furnished by people in 

 general of a given age, we often prefer the narrower tables 

 furnished by men of a particular profession, abode, or mode 

 of life. The reader may however be conveniently reminded 

 here that in so doing we must not suppose that we are able, 

 by any such device, in any special or peculiar way to secure 

 truth. The general average, if persistently adhered to 

 throughout a sufficiently wide and varied experience, would 

 in the long run tend to give us the truth ; all the advantage 

 which the more special averages can secure for us is to give 

 us the same tendency to the truth with fewer and slighter 

 aberrations. 



4. Returning then to our witness, we know that if 

 we have a very great many statements from him upon all 

 possible subjects, we may feel convinced that in nine out of 

 ten of these he will tell us the truth, and that in the tenth 

 case he will go wrong. This is nothing more than a matter 

 of definition or consistency. But cannot we do better than 

 thus rely upon his general average ? Cannot we, in almost 

 any given case, specialize it by attending to various cha 

 racteristic circumstances in the nature of the statement 

 which he makes ; just as we specialize his prospects of 

 mortality by attending to circumstances in his constitution 

 or mode of life ? 



Undoubtedly we may do this ; and in any of the practical 

 contingencies of life, supposing that we were at all guided 



