iS6 



INDUCTION. 



inquiry, Induction may be defined, the 

 operation of discovering and proving 

 general propositions. It is true that 

 (as already shown) the process of in- 

 directly ascertaining individual facts 

 is as truly inductive as that by which 

 we establish general truths. But it 

 is not a different kind of induction ; 

 it is a form of the very same process : 

 since, on the one hand, generals are 

 but collections of particulars, definite 

 in kind but indefinite in number ; and 

 on the other hand, whenever the evi- 

 dence which we derive from observa- 

 tion of known cases justifies us in 

 drawing an inference respecting even 

 one unknown case, we should on the 

 same evidence be justified in drawing 

 a similar inference with respect to a 

 whole class of cases. The inference 

 either does not hold at all, or it holds 

 in all cases of a certain description ; 

 in all cases which, in certain definable 

 respects, resemble those we have ob- 

 served. 



If these remarks are just ; if the 

 principles and rules of inference are 

 the same whether we infer general 

 propositions or individual facts ; it 

 follows that a complete logic of the 

 sciences would be also a complete 

 logic of practical business and com- 

 mon life. Since there is no case of 

 legitimate inference from experience, 

 in which the conclusion may not 

 legitimately be a general proposition, 

 an analysis of the process by which 

 general truths are arrived at is vir- 

 tually an analysis of all induction 

 whatever. Whether we are inquir- 

 ing into a scientific principle or into 

 an individual fact, and whether we 

 proceed by experiment or by ratio- 

 cination, every step in the train of 

 inferences is essentially inductive, 

 and the legitimacy of the induction 

 depends in both cases on the same 

 conditions. 



True it is that in the case of the 

 practical inquirer, who is endeavour- 

 ing to ascertain facts not for the pur- 

 poses of science but for those of busi- 

 ness, such, for instance, as the advocate 

 or the judge, the chief difficulty is one 



in which the principles of induction 

 will afford him no assistance. It 

 lies not in making his inductions, 

 but in the selection of them ; in choos- 

 ing from among all general proposi- 

 tions ascertained to be trtie, those 

 which furnish marks by which he 

 may trace whether the given subject 

 possesses or not the predicate in 

 question. In arguing a doubtful 

 question of fact before a jury, the 

 general propositions or principles to 

 which the advocate appeals are mostly, 

 in themselves, sufficiently trite, and 

 assented to as soon as stated : his 

 skill lies in bringing his case under 

 those propositions or principles ; in 

 calling to mind such of the known or 

 received maxims of probability as ad- 

 mit of application to the case in hand, 

 and selecting from among them those 

 best adapted to his object. Success 

 is here dependent on natural or ac- 

 quired sagacity, aided by knowledge 

 of the particular subject and of sub- 

 jects allied with it. Invention, though 

 it can be cultivated, cannot be reduced 

 to rule ; there is no science which will 

 enable a man to bethink himself of 

 that which will suit his purpose. 



But when he has thought of some- 

 thing, science can tell him whether 

 that which he has thought of will 

 suit his purpose or not. The inquirer 

 or arguer must be guided by his own 

 knowledge and sagacity in the choice 

 of the inductions out of which he will 

 construct his argument. But the vali- 

 dity of the argument when constructed 

 depends on principles and must be 

 tried by tests which are the same for 

 all descriptions of inquiries, whether 

 the result be to give A an estate, or 

 to enrich science with a new general 

 truth. In the one case and in the 

 other, the senses, or testimony, must 

 decide on the individual facts ; the 

 rules of the syllogism will determine 

 whether, those facts being supposed 

 correct, the case really falls within 

 the formulae of the different induc- 

 tions under which it has been suc- 

 cessively brought ; and finally, the 

 legitimacy of the inductions them- 



