VITALISTIC POSITION UNTENABLE 29 



knowledge of these processes. Yet the vital 

 principle is assumed to act unconsciously. 

 The very nature of the vitalistic assumption 

 is thus totally unintelligible. From this 

 point of view also the hypothesis is useless : 

 for even if we cannot completely understand 

 a living organism by the aid of physics and 

 chemistry, we do not improve matters by 

 postulating an agency which is itself entirely 

 unintelligible. 



In one form or another these objections 

 to vitalism have been urged repeatedly, and 

 there has been no satisfactory reply to them. 

 On the other hand, there have been very 

 effective retorts from the vitalistic side 

 against the mechanistic theory. It is not 

 these retorts that concern us at present, how 

 ever, but the inherent untenability of the 

 vitalistic position. If the mechanistic theory 

 is wrong, this does not prove that the theory 

 of the vitalists is right, so that the objections 

 to vitalism lose none of their force. 



Let us now try to sum up the position 

 reached at the end of this lecture. The 

 mechanistic theory of life has been stated in 

 outline. It evidently affords to biologists a 



