414 Credibility of Extraordinary Stories. [CHAP. XVII. 



that a person whom I have long known, and of whose mea 

 sure of veracity and judgment I may be supposed therefore 

 to have acquired some knowledge, informs me that there is 

 something to my advantage if I choose to go to certain 

 trouble or expense in order to secure it. As regards the 

 general veracity of the witness, then, there is no difficulty; 

 we suppose that this is determined for us. But as regards 

 his story, difficulty arid vagueness emerge at every point. 

 What is the number of balls in the bag here ? What in fact 

 are the nature and contents of the bag out of which we sup 

 pose the drawing to have been made ? It does not seem 

 that the materials for any rational judgment exist here. 

 But if we are to get at any such amended figure of veracity 

 as those attained in the above example, these questions must 

 necessarily be answered with some degree of accuracy; for 

 the main point of the method consists in determining how 

 often the event must be considered not to happen, and thence 

 inferring how often the witness will be led wrongly to assert 

 that it has happened. 



It is not of course denied that considerations of the kind 

 in question have some influence upon our decision, but only 

 that this influence could under any ordinary circumstances 

 be submitted to numerical determination. We are doubt 

 less liable to have information given to us that we have 

 come in for some kind of fortune, for instance, when no 

 such good luck has really befallen us ; and this not once 

 only but repeatedly. But who can give the faintest inti 

 mation of the nature and number of the occasions on which, 

 a blank being thus really drawn, a prize will nevertheless 

 be falsely announced ? It appears to me therefore that 

 numerical results of any practical value can seldom, if ever, 

 be looked for from this method of procedure. 



9. Our conclusion in the case of the lottery, or, what 



