340 The Theory of ISIatural Selection 



latter case there is a positive separation for further breeding 

 of those individuals that show desirable traits. Under nat- 

 ural conditions the selection is entirely negative. That is 

 to say, those that do not come up to a certain standard are 

 ruthlessly eliminated by the many enemies and forces against 

 which a living thing must struggle. Darwin made the fur- 

 ther distinction between the conscious selection of the 

 breeder and the ruthless destruction by nature, in which 

 he refused to assume a conscious purpose. This is an im- 

 portant point which is frequently overlooked by the follow- 

 ers of Darwin as well as by his opponents and it was some- 

 times overlooked by Darwin himself. Darwin explicitly 

 stated that he did not intend to personify nature. He rec- 

 ognized clearly enough that the personification of nature, 

 in his theory of natural selection, would simply evade the 

 responsibility for finding a scientific explanation of evolution 

 just as did Lamarck's *' inner strivings." 



To postulate a conscious purposeful entity driving and 

 guiding the natural processes leaves us without any need 

 (and probably without any possibility) of searching fur- 

 ther into causative relations. Every problem can be solved 

 by assuming an unknown and unknowable principle whether 

 we call it nature or divine intelligence. The scientist who 

 adheres rigidly to the principles of his calling will refuse to 

 consider such a solution, notwithstanding his frequent ne- 

 cessity of acknowledging his utter ignorance. Ideally, he 

 would rather say frankly, " I don't know," than hide his 

 ignorance behind a phrase which seems superficially to an- 

 swer the question but which in reality says, *' I don't know." 



The doctrine itself is simple enough. Plants and ani- 

 mals vary. They cannot all attain maturity and reproduce 

 themselves. They are destroyed and obstructed at every 

 turn by a variety of forces and enemies. Those who do at 

 last survive and leave progeny are those who can meet the 

 severe demands which nature makes upon life. They are the 

 fit. They are favored by nature in having been born with 

 their useful factors or with the ability to meet the struggle 



