CHAPTEE VII. 



INDUCTION. 



WE enter in this chapter upon the second great de 

 partment of logical method, that of Induction or the 

 Inference of general from particular truths. It cannot 

 be said that the Inductive process is of greater importance 

 than the Deductive process already considered, because the 

 latter process is absolutely essential to the existence of 

 the former. Each is the complement and counterpart of 

 the other. The principles of thought and existence which 

 underlie them are at the bottom the same, just as subtrac 

 tion of numbers necessarily rests upon the same principles 

 as addition. Induction is, in fact, the inverse operation 

 to deduction, and cannot be conceived to exist without 

 the corresponding operation, so that the question of re 

 lative importance cannot arise. Who thinks of asking 

 whether addition or subtraction is the more important 

 process in arithmetic 1 But at the same time much 

 difference in difficulty may exist between a direct and 

 inverse operation ; the integral calculus, for instance, is 

 almost infinitely more difficult than the differential cal 

 culus of which it is the inverse. It must be allowed 

 that in logic inductive investigations are of a far higher 

 degree of difficulty, variety, and complexity than any 

 questions of deduction ; and it is this fact no doubt which 

 has led some logicians to erroneous opinions concerning 

 the exclusive importance of induction. 



Hitherto we have been engaged in considering how 



