404 Testimony. [CHAP. XVK 



self in other directions also. It has, for instance, been already 

 pointed out that the individual characteristics of any sick 

 man s disease would be quite sufficiently important in most 

 cases to prevent any surgeon from judging about his recovery 

 by a genuine and direct appeal to statistics, however such 

 considerations might indirectly operate upon his judgment. 

 But if an opinion had to be formed about a considerable 

 number of cases, say in a large hospital, statistics might 

 again come prominently into play, and be rightly recognized 

 as the principal source of appeal. We should feel able to 

 compare one hospital, or one method of treatment, with 

 another. The ground of the difference is obvious. It arises 

 from the fact that the characteristics of the individuals, 

 which made us so ready to desert the average when we had 

 to judge of them separately, do not produce the same dis 

 turbance when we have to judge about a group of cases. 

 The averages then become the most secure and available 

 ground on which to form an opinion, and therefore Pro 

 bability again becomes applicable. 



But although some resort to Probability may be ad 

 mitted in such cases as these, it nevertheless does not 

 appear to me that they can ever be regarded as particularly 

 appropriate examples to illustrate the methods and resources 

 of the theory. Indeed it is scarcely possible to resist the 

 conviction that the refinements of mathematical calculation 

 have here been pushed to lengths utterly unjustifiable, when 

 we bear in mind the impossibility of obtaining any corre 

 sponding degree of accuracy and precision in the data from 

 which we have to start. To cite but one instance. It would 

 be hard to find a case in which love of consistency has pre 

 vailed over common sense to such an extent as in the ad 

 mission of the conclusion that it is unimportant what are 

 the numbers for and against a particular statement, provided 



