352 INDUCTION. 



pleteness or tlie incompleteness of our assurance of their truth. There 

 remain, however, a class of propositions avowedly not universal ; in 

 which if is not pretended that the predicate is always true of the 

 subject; but the value of which, as generalizations, is nevertheless 

 extremely sreat. An imj^ortant portion of the field of inductive 

 knowledo-e does not consist of universal truths, but of approximations 

 to such truths ; and when a conclusion is said to rest upon probable 

 evidence, the premisses it is drawn from are usually generalizations of 

 this sort. ■ 



As every certain inference respecting a particular case, -implies that 

 there is ground for a general proposition, of the form, Every A is Bj 

 so does every probable inference suppose that there is ground for a 

 proposition of the form, Most A are B : and the degree of probability 

 of the inference in an average case, will depend upon the proportion 

 between the number of instances existing in nature which accord with 

 the generalization, and the number of those which conflict with it. 



§ 2. Propositions in tlie form, Most A are B, are of a very different 

 degree of importance in science, and in the practice of life. To the 

 scientific inquirer they ai"e valuable cliiefly as materials for, and steps 

 towards, universal truths. The discovery of these is the proper end 

 of science: its work is not done if it stops at the proposition that a 

 majority of A are B, without circumscribing that majoiity by some 

 common character, fitted to distinguish them from the minority. Inde- 

 pendently of the inferior precision of such imperfect generalizations, 

 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 discovering ulterior truths by way of 

 deduction. We may, it is true, by combining the proposition. Most A 

 are B, with an universal proposition, Every B is C, anive at the con- 

 clusion that most A are G. But when a second proposition of the 

 approximate kind is introduced — or even when there is but one, if 

 that one be the major pi^miss — nothing can 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 D, Though the majority of the class B have the 

 attribute signified by D, the whole of the sub-class A may belong to 

 the minority. 



Though so little use can be made, in science, of approxin^iate gen- 

 'eralizations, except as a stage on the road to something better, for 

 practical guidance they are often all we have to rely ujjon. Even 

 when science has really determined the universal laws of any phe- 

 nomenon, 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 die existence 

 of a phenomenon can be proved by what have been scientifically 

 ascertained to be uinversal marks of it. To be indecisive and 

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

 clusive character to act upon, is a defect sometimes incident to scientific 

 minds, but which, vvherever it exists, renders them unfit for practical 

 emergenpies. If we would succeed in action, we must judge by indi- 

 cations' whiph, although they do not generally mislead us, sometimes 



