208 HUMAN BIOLOGY 



operations. In his remarkable essay on the logic of physics, 

 Bridgman shows that a concept must involve as much as, 

 and nothing more than, the set of operations by which it is 

 determined. Concepts can be defined only in the range of 

 actual experiments, and when they cannot be so defined, 

 they are meaningless. 



If meaningless and useless questions were banished from 

 natural sciences, the road to progress would be freer. Biolo- 

 gists have more or less entangled themselves in philosophic 

 and scientific systems. Those who belong to the vitalistic 

 school believe that the integrating principle that makes 

 a whole of the organism cannot be expressed in physico- 

 chemical terms. The mechanisms responsible for the organic 

 unity would be directed by an independent agent, a govern- 

 ing idea, analogous to that of an architect in the construction 

 of a building. The more eminent exponent of vitalism, 

 Driesch, teaches that certain classes of natural facts are not of 

 the physicochemical type, but possess an autonomy of their 

 own. The autonomous agent at work in the vital processes, 

 called entelechy by Driesch, is something that is non- 

 physicochemlcal. However, it is not psychical. It is of a 

 non-energetic character and cannot create energy. It is 

 concerned only with the arrangement of the manifoldness. 

 This definition of entelechy shows that it is quite outside 

 of the realm of positive investigation. The hypothesis of a 

 non-physicochemical force within the organism and at the 

 same time independent of the organism cannot inspire 

 any new line of research. It is a pure mental construct, 

 impossible to reach and to measure. It will contribute no 

 more to the finding of new biological laws than the belief in 

 Naiads presiding over the fate of springs has helped in the 

 discovery of the laws of hydrodynamics. Although it may 

 be of real philosophical interest, such a concept should be 

 discarded by biologists as being meaningless. The classical 

 mechanisticism that has superseded vitalism does not 

 express a sounder intellectual attitude. It claims that the 

 application of the scientific method exhausts the content 

 of natural phenomena, and that all physiological processes 

 can be explained in terms of the present laws of physico- 

 chemistry. These pretensions are obviously unwarranted. 



