212 THE SCIENCE OF BIOLOGY 



Opposed to the doctrine that the animal body is a ma- 

 chine, whose responses are predictable in terms of a mechan- 

 ism, is the doctrine of vitalism, by which it is maintained that 

 the actions of the living body involve something which is not 

 present in any non-living machine. Of course, the mechan- 

 ist does not maintain that all vital processes have been re- 

 duced to mechanical principles. He only maintains, as his 

 working hypothesis, that they will be so reduced when we 

 know more about them. The vitalist maintains, as his hy- 

 pothesis, that mechanistic explanations are insufficient. 

 The whole question of mechanism versus vitalism has prob- 

 ably attracted much more attention than it deserves. The 

 agnostic position would seem the only tenable one for a 

 long time to come. The vitalist should remember that 

 biological progress seems to be made in the direction of 

 mechanistic explanations. The mechanist should remember 

 the complexity of the phenomena and the scant progress 

 that has been made toward their comprehensive solution. 

 Moreover, undue emphasis of the mechanistic conception 

 has certain important human implications, which the mech- 

 anist tends to overlook. 26 As a practical question, the 

 adoption of a mechanistic conception of human behavior 



basis for his theories. The ideas of H. S. Jennings, expressed in his "Behavior 

 of the Lower Organisms" and numerous special papers, have always seemed 

 to the writer to represent a discriminating outlook upon the behavior problem 

 as a whole. 



26 These implications are well stated by S. O. Mast, loc. cit., who writes as 

 follows: "Mechanism implies, as previously pointed out, that every phenom- 

 enon is specifically associated with changes in the special interrelationship of 

 material particles, masses or systems, changes in or states in material con- 

 figurations, which are absolutely determined by preceding changes or states in 

 material configuration. Consequently, if mechanism holds, every phenom- 

 enon, every act of every organism that ever existed, exists now, or ever will 

 exist, is absolutely determined with reference to character, time and place and 

 has been thus absolutely determined from the very beginning. If you can in 

 reality, at any given instant, move your hand either to the right or to the left, 

 mechanism breaks down, for according to the laws of mechanics, if you move 

 your hand to the right, that movement is by the material configuration within 

 and about you absolutely determined with reference to place, extent, duration 

 and time and you could not possibly have moved it to the left at that time." 



