LIMITATIONS 89 



II 



It does not follow that, because the theory of natural 

 evolution is to be accepted, it is therefore to be regarded 

 as capable of accounting for all the characteristics of 

 organic life. The theory has certain very definite 

 limitations, and I wish to draw your attention to them. 



I have called the evolutionary theory a "physical 

 description." It describes rather than accounts for 

 the process of species forming, and is concerned with 

 its physical aspects, its evidence being drawn from 

 physical phenomena. Such evidence affords absolutely 

 no warrant for the inference that the evolutionary theory 

 explains the origin of anything superphysical. If, 

 therefore, a species is found to possess superphysical 

 characteristics, the development of that species can be 

 but partially explained by a physical evolution theory. 



Those who accept the naturalistic philosophy will 

 of course reject my argument, because they assume that 

 all knowable realities are capable of being interpreted 

 in physical and mechanical terms. Naturalism, how- 

 ever, is not science, but an indefensible outcome of 

 one-sided speculation. Many leading natural scien- 

 tists recognize this, and realize that certain phenom- 

 ena of organic life are not susceptible of exclusively 

 mechanical explanation, but require superphysical 



is the final word of science. The possibility remains that wider 

 knowledge may hereafter require a modification, or even an abandon- 

 ment, of the theory in question. But natural evolution is the exist- 

 ing scientific doctrine, and as such we have to reckon with it. 



