INDUCTION IN GENERAL. 315 



among all general propositions ascertained to be true, 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 them 

 selves, sufficiently trite, and assented to as soon as stated : his 

 skill lies in bringing his case under those propositions or prin 

 ciples ; in calling to mind such of the known or received maxims 

 of probability as admit 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 acquired sagacity, aided 

 by knowledge of the particular subject, and of subjects allied 

 with it. Invention, though it can be cultivated, cannot be re 

 duced 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 something, 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 know 

 ledge and sagacity in the choice of the inductions out of which 

 he will construct his argument. But the validity of the argu 

 ment 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 inductions under which it has been successively 

 brought ; and finally, the legitimacy of the inductions them 

 selves must be decided by other rules, and these it is now our 

 purpose to investigate. If this third part of the operation be, in 

 many of the questions of practical life, not the most, but the least 

 arduous portion of it, we have seen that this is also the case in 

 some great departments of the field of science ; in all those 

 which are principally deductive, and most of all in mathematics; 

 where the inductions themselves are few in number, and so 

 obvious and elementary that they seem to stand in no need of 

 the evidence of experience, while to combine them so as to 



