Mechanism, Vitalism, and Teleology 359 



latter case one needs to take into account many hereditary 

 and environmental factors; one needs to know the breed 

 and size of the dog, whether he is at home or not, whether 

 the one who kicks is a stranger or not, etc. There is good 

 reason to believe that when all these factors are taken into 

 account the results in the case of the dog would be as pre- 

 dictable as in that of the stone. Certainly none of the cases 

 cited by Bergson proves that the activities of animals are 

 indeterminate and non-mechanistic. 



Driesch also has maintained that adaptive responses in 

 general cannot be explained by mechanistic science. His first 

 proof of vitalism is that a living thing is a "harmonic, equi- 

 potential system" ; that is, "the pattern of the whole exists 

 in every part," and under suitable conditions a fragment of 

 an egg, embryo, or adult can give rise to a typical whole. 

 Likewise, when the cells and nuclei of segmenting eggs are 

 forced out of their normal positions by pressure normal 

 development may result, and Driesch holds that neither 

 cytoplasm, nucleus, nor medium are the causes of differentia- 

 tion, but that "the fate of a part is a function of its position" 

 in the whole, and that "any part is capable of any fate."" 

 Some organisms may be cut up in the three dimensions of 

 space and yet each fragment that is sufficiently large may 

 give rise to a complete organism like the original one. It 

 is inconceivable, he says, that any machine could be broken 

 up in this way and yet the parts be capable of becoming 

 complete. He therefore concludes that something, not 

 mechanistic nor causal, lies in the background of develop- 

 ment; this something he calls, in the language of Aristotle, 

 "entelechy." 



His second proof of vitalism is drawn from the genesis 

 of this complex equipotential system. It is absurd to sup- 

 pose, he says, that any machine could give rise to such a sys- 



