INDUCTION IN GENERAL. 349 



in his choice of the inductions out of which he will 

 construct his argument. But the validity of the 

 argument when constructed, depends upon 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 themselves 

 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 expe- 

 rience, while to combine them so as to prove a given 

 theorem or solve a problem, may call for the highest 

 powers of invention and contrivance with which our 

 species is gifted. 



If the identity of the logical processes which prove 

 particular facts and those which establish general 

 scientific truths, required any additional confirmation, 

 it would be sufficient to consider, that in many 

 branches of science single facts have to be proved, as 

 well as principles ; facts as completely individual as 

 any that are debated in a court of justice ; but which 

 are proved in the same manner as the other truths of 



