Nature or Evolutionary Progress 37 



technique and how critical the experimentation, 

 physical changes are found to give rise to changes in 

 sensations, emotions, desires, purposes, thoughts. A 

 formulation of experience that ignored or denied 

 these observational and experimental relations would 

 be a mere caricature, worthless as a guide to action 

 and ridiculous as a pretender to enlightenment. Our 

 inner experiences are not independent of outer occur- 

 rences. 



This disposes, for science, of the a priori argument 

 that there can be no functional interrelations between 

 these two classes of things. Experimentally, observa- 

 tionally, there are functional relations ; and science is 

 but a formulation of relations discovered by observa- 

 tion and experiment. As investigation progresses, it 

 becomes more and more clear that to each type of 

 sensation or emotion or other inner experience there 

 corresponds functionally some type of physical con- 

 dition. When the typical physical condition is altered, 

 the mental experience is likewise altered. 



But how then about the converse relation ? Do sen- 

 sations, emotions, purposes, thoughts, knowledge, and 

 the like, affect motion, physical conditions, behavior.? 

 Is it true that knowledge is power .^^ Is intelligence 

 indeed a guide to action .? Or have these things nothing 

 to do with our actions.? 



The a priori argument that one of these sets of 

 things cannot affect the other, we have already seen 

 to be overthrown by the formulation of experience. 

 The experimentally demonstrated fact that physical 



