38 THE METHOD OF DARWIN. 



It has been said that deduction, regarded 

 merely as a logical process, is equally valid 

 whether the premises are assumed to be true 

 or are admitted to be hypothetical. If the 

 premises are true, the conclusion must be true. 

 What brought the old deductive process into 

 so general disrepute was not its inadequacy, 

 but the using as premises in the process prin- 

 ciples that were held to be beyond dispute. 

 To this end the a priori reasoner went farther 

 and farther back in his philosophical repertory, 

 until he reached principles or axioms that he 

 felt could not be denied. Then by an irre- 

 sistible deductive swoop he reached conclu- 

 sions that must likewise be true. In such 

 philosophy there is little need of verification. 



In science, and therefore also in the reason- 

 ing of practical life, the great question always 

 is whether the premises are true, or partly 

 true, or false. The old notion was that deduc- 

 tion led to certainty, and induction did not. 

 But in the scientific method the object is not 

 merely to deduce consequences from laws or 

 principles, but to establish the truth or falsity 

 of those laws or principles themselves. Hence 

 there is an incessant interplay of induction 

 and deduction. Darwin's distrust of deductive 

 reasoning was due to his fear of the premises. 



