262 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



individuals in the offspring than can grow up under the 

 given conditions, therefore there will be a struggle for 

 existence amongst them which only the fittest will survive; 

 these survivors may be said to have been " selected ' by 

 natural means. 



It must be certain from the very beginning of analysis 

 that natural selection, as defined here, can only eliminate 

 what cannot survive, what cannot stand the environ- 

 ment in the broadest sense, but that natural selection never 

 is able to create diversities. It always acts negatively 

 only, never positively. And therefore it can " explain " 

 if you will allow me to make use of this ambiguous word 

 it can " explain " only why certain types of organic specifica- 

 tions, imaginable a priori, do not actually exist, but it never 

 explains at all the existence of the specifications of animal 

 and vegetable forms that are actually found. In speaking 

 of an " explanation " of the origin of the living specific forms 

 by natural selection one therefore confuses the sufficient 

 reason for the non-existence of what there is not, with the 

 sufficient reason for the existence of what there is. To say 

 that a man has explained some organic character by 

 natural selection is, in the words of Nageli, the same as if 

 some one who is asked the question, " Why is this tree 

 covered with these leaves," were to answer "Because the 

 gardener did not cut them away." Of course that would 

 explain why there are no more leaves than those actually 

 there, but it never would account for the existence and 

 nature of the existing leaves as such. Or do we understand 

 in the least why there are white bears in the Polar Eegions 

 if we are told that bears of other colours could not survive ? 



In denying any real explanatory value to the concept 



