150 S. J. HOLMES 



different nature: (1) the problem of how behavior is modified 

 by its results, and (2) the problem of why pleasure is associated 

 with certain physiological activities such as securing movements 

 and pain with others such as avoiding movements. The latter 

 problem is one whose solution appears holpeless. If we accept 

 the doctrines of psycho-physical parallelism in any of its forms, 

 we must deny that psychical states are, strictly speaking, the 

 causes of physical changes. Why then should pleasure be con- 

 nected with one kind of activity and pain with another? Why not 

 just the reverse? This problem is, I believe, insoluble, because 

 it is a question of the relation of the physical and the psychical; 

 it is of essentially the same nature as the question why one kind 

 of retinal stimulation produces a sensation of red and another a 

 sensation of green. Physical and psychical states are correlated 

 in particular ways; this we accept as a matter of observed con- 

 nection. But why a certain kind of brain vibration is associated 

 with a state of consciousness we call a sensation of red instead of 

 some other state is a question upon which we may intend our 

 minds indefinitely without the least profit. If we adopt any 

 other theory of the relation of mind and body we are in no way 

 better off. If we have to do with a preordained connection of 

 pleasure with certain physiological activities and pain with cer- 

 tain others, this connection is no more intelligible if we admit the 

 interaction of psychical and physical states than it is under the 

 theory of parallelism. We can only say that such is the observed 

 relation of the phenomena. It may be regarded therefore as a 

 piece of good luck that we are constituted so as to pursue pleasure 

 and avoid pain. We might have been endowed with a fatal 

 tendency to do just the reverse. Pain instead of pleasure would 

 then have been the correlate of physical well being; those forms 

 in which the painful corresponded with the organically good 

 would have been preserved, the others would have perished; 

 and thus there would have been established a correlation between 

 what is sought and what is conducive to organic welfare, as there 

 is now, but of a quite different kind. 



There is another way of looking at the problem which avoids the 

 difficulty we have mentioned ; and that is to suppose that pleasure 



