130 INDUCTION. 



to direct us but the approximate generalization, that truth is 

 more common than falsehood, or, in other words, that most 

 persons, on most occasions, speak truth. But if we consider 

 in what circumstances the cases where truth is spoken differ 

 from those in which it is not, we find, for instance, the follow 

 ing : the witness s being an honest person or not ; his being 

 an accurate observer or not ; his having an interest to serve in 

 the matter or not. Now, not only may we be able to obtain 

 other approximate generalizations respecting the degree of 

 frequency of these various possibilities, but we may know which 

 of them is positively realized in the individual case. That the 

 witness has or has not an interest to serve, we perhaps know 

 directly ; and the other two points indirectly, by means of 

 marks ; as, for example, from his conduct on some former oc 

 casion ; or from his reputation, which, though a very uncertain 

 mark, affords an approximate generalization (as, for instance, 

 Most persons who are believed to be honest by those with whom 

 they have had frequent dealings, are really so) which approaches 

 nearer to an universal truth than the approximate general pro 

 position with which we set out, viz. Most persons on most 

 occasions speak truth. 



As it seems unnecessary to dwell further on the question of 

 the evidence of approximate generalizations, we shall proceed 

 to a not less important topic, that of the cautions to be observed 

 in arguing from these incompletely universal propositions to 

 particular cases. 



5. So far as regards the direct application of an approxi 

 mate generalization to an individual instance, this question 

 presents no difficulty. If the proposition, Most A are B, has 

 been established, by a sufficient induction, as an empirical law, 

 we may conclude that any particular A is B with a probability 

 proportioned to the preponderance of the number of affirmative 

 instances over the number of exceptions. If it has been found 

 practicable to attain numerical precision in the data, a corre 

 sponding degree of precision may be given to the evaluation 

 of the chances of error in the conclusion. If it can be esta 

 blished as an empirical law that nine out of every ten A are B, 



