Mechanism, Vitalism, and Teleology 357 



vitalism is not only that it is more intelligible but also that 

 it encourages scientific investigation, whereas a thorough- 

 going belief in vitalism discourages research. 



Of late several notable attacks have been made upon the 

 mechanistic conception of life, particularly with reference 

 to the causes of adaptation. Bergson, Driesch, Noll, Pauly, 

 Reinke, Schneider, Thomson, G. Wolff and other "neo- 

 vitalists" hold that many vital processes are indeterminate, 

 non-predictable, non-mechanistic, and creative ; they attempt 

 to solve the riddles of life by a direct appeal to mysterious 

 conditions or principles which are found only in living things. 



Bergson's evidence for his elan vital is found in part in 

 phenomena of parallel or convergent evolution. He main- 

 tains that, starting from different sources and proceeding by 

 wholly different routes, organisms may reach the same termi- 

 nus. For example, he holds that the eye of the mollusk, 

 Pecten, and the eye of a vertebrate are practically the same 

 in structure, though they have evolved by wholly different 

 paths and from wholly different sources; or again, that 

 societies of ants and of men are fundamentally alike, al- 

 though they have evolved in entirely different ways. If iden- 

 tical results can thus come from wholly different causes, 

 there is scientific indeterminism, and some principle other 

 than cause and effect must be involved, some form of vital- 

 ism rather than mechanism. 



But neither in the living nor the not-living world do iden- 

 tical results come from dissimilar causes; in short, conver- 

 gent evolution does not result in identical structures. When 

 Mivart denied that homologies are evidences of evolution 

 and claimed that the eye of a cuttle-fish and the eye of a 

 vertebrate were homologous, though they could not have had 

 a common origin, Darwin replied by showing that these two 

 types of eyes are in no sense homologous; that is, they are 



