SECT. 11.] Credibility of Extraordinary Stories. 417 



confirmation, more or less, according to his judgment and 

 probity, but at any rate to offer an improvement upon the 

 mere guesser. If, however, we will give heed to his mere 

 guess we are doing just the same thing as if we were to guess 

 ourselves, in which case of course the odds that we are right 

 are simply measured by the frequency of occurrence of the 

 events. 



We cannot quite so readily apply the same rule to the 

 other case, namely to that of the numbered balls, for there 

 the witness who is right every other time may really be a 

 very fair, or even excellent, witness. If he has many ways 

 of going wrong, and yet is right in half his statements, it is 

 clear that he must have taken some degree of care, and can 

 not have merely guessed. In a case of yes or no, any one can 

 be right every other time, but it is different where truth 

 is single and error is manifold. To represent the case of a 

 simply worthless witness when there were 1000 balls and 

 the drawing of one assigned ball was in question, we should 

 have to put his figure of veracity at T ^. If this were 

 done we should of course get a similar result. 



11. It deserves notice therefore that the figure of 

 veracity, or fraction representing the general truthfulness 

 of a witness, is in a way relative, not absolute ; that is, it 

 depends upon, and varies with, the general character of the 

 answer which he is supposed to give. Two witnesses of 

 equal intrinsic veracity and worth, one of whom confined 

 himself to saying yes and no, whilst the other ventured to 

 make more original assertions, would be represented by 

 different fractions; the former having set himself a much 

 easier task than the latter. The real caution and truthful 

 ness of the witness are only one factor, therefore, in his 

 actual figure of veracity; the other factor consists of the 

 nature of his assertions, as just pointed out. The ordinary 

 v. 27 



