300 Darwinism and Other Essays. 



scientific thinking. To acquire expertness and 

 elegance in the use of deductive methods, while 

 remaining contentedly ignorant of the fundamen 

 tal canons of induction, is to secure but a lame 

 and one-sided mental development. It is often 

 remarked that many men, whose opinions upon 

 any subject with which they are familiar are sober 

 enough, do not scruple to utter the most childish 

 nonsense upon topics with which they are only 

 partially acquainted. The reason is that they 

 have learned to think correctly after some par 

 ticular fashion, but know nothing of the general 

 principles on which thinking should be conducted. 

 They are what is fitly called narrow-minded ; 

 and since each branch of knowledge is more or 

 less closely interlaced with every other branch, a 

 searching scrutiny will usually show that even in 

 their control of their own specialty there is ample 

 room for improvement. Each science has its log 

 ical methods and its peculiar species of evidence ; 

 and to insure an harmonious development of the 

 mental powers, there is no practicable way except 

 to obtain a knowledge of all. 



To acquire such a command of scientific meth 

 ods, it is not necessary, even were it possible, to 

 devote much study to the details of each separate 

 science. To master the details of any single sci- 



