APPROXIMATE GENERALIZATION S. 125 



character, fitted to distinguish them from the minority. Inde 

 pendently of the inferior precision of such imperfect generali 

 zations, and the inferior assurance with which they can be 

 applied to individual cases, it is plain that, compared with 

 exact generalizations, they are almost useless as means of dis 

 covering ulterior truths by way of deduction. We mav, it is 

 true, by combining the proposition Most A are B, with an 

 universal proposition, Every B is C, arrive at the conclusion 

 that Most A are C. But when a second proposition of the 

 approximate kind is introduced, or even when there is but 

 one, if that one be the major premise, nothing can in general 

 be positively concluded. When the major is Most B are D, 

 then, even if the minor be Every A is B, we cannot infer that 

 most A are D, or with any certainty that even some A are 1). 

 Though the majority of the class B have the attribute signi 

 fied by I), the whole of the sub-class A may belong to the 

 minority.* 



Though so little use can be made, in science, of approxi 

 mate generalizations, except as a stage on the road to some 

 thing better, for practical guidance they are often all we have 

 to rely on. Even when science has really determined the 

 universal laws of any phenomenon, not only are those laws 

 generally too much encumbered with conditions to be adapted 

 for every-day use, but the cases which present themselves in 

 life are too complicated, and our decisions require to be taken 

 too rapidly, to admit of waiting till the existence of a phe 

 nomenon can be proved by what have been scientifically ascer 

 tained to be universal marks of it. To be indecisive and 

 reluctant to act, because we have not evidence of a perfectly 

 conclusive character to act on, is a defect sometimes incident 

 to scientific minds, but which, wherever it exists, renders them 

 unfit for practical emergencies. If we would succeed in action, 

 we must judge by indications which, though they do not 



* Mr. De Morgan, in his Formal Logic, makes the just remark, that from 

 two such premises as Most A are B, and Most A are C, we may infer willi 

 certainty that some B are C. But this is the utmost limit of the conclusions 

 which can be drawn from two approximate generalizations, when the precise 

 degree of their approximation to universality is unknown or undefined. 



