CONCEPTIONS AND METHODS OF PSYCHOLOGY 595 



whether vital phenomena may be reduced to the laws of matter 

 in motion, but the relations between sensations and the physical 

 stimulus. Pearson tells us in his Grammar of Science that if the 

 cortex of one brain were connected with another by a commissure 

 of nerve substance, there would be "physical verification of other 

 consciousness." Ostwald lets energy do hermaphroditic service in 

 the physical and the extra-physical households. 



But it is not certain that such ingenuous commingling of the 

 mental and the physical worlds is more repugnant to common 

 sense or natural science than the logical subtleties of the schools, 

 which undertake to define, relate, or obliterate them. It is gen- 

 erally assumed that a psychologist must be either an interactionist 

 or a parallelist. According to the definitions with which our psych- 

 ologies start, it is indeed true that mind and matter must either 

 interact or in some way correspond without interaction. If the 

 psychologist asserts that each brain is a centre for the creation of 

 new energy or for interference with the configuration of a material 

 system, he obviously subverts the principal generalizations of phys- 

 ical science. He doubtless has a right to do so, but in the same 

 sense as the cow has a right to stop the locomotive engine. If, on 

 the other hand, the psychologist modestly admits that mind does 

 not affect the physical order, he runs counter to the principal gen- 

 eralization of biological science. If pleasure and pain, memory 

 and forethought, are of no use in the struggle for organic survival, 

 why should they ever have evolved? 



It requires less temerity to question the theories of biology than 

 to deny the laws of physics. The survival of the fit may be regarded 

 as a truism rather than as a discovery, if we call that fit which 

 does survive. But fitness of this kind is so protean in its mani- 

 festations in organic nature that the formula becomes somewhat 

 vague. If an animal is inconspicuously colored, it is protective 

 coloration, and so useful; if conspicuously colored, it is directive 

 coloration, and so useful. It is somewhat difficult to guess the 

 utility of the fantastic shape and color of each deep-sea fish that 

 lives in perpetual darkness. Then there are admittedly correlated 

 variations, by-products of evolution, diseases and the like; it may 

 be that consciousness is that sort of thing. If some kinds of con- 

 sciousness, as the sense of beauty, are of no use in the struggle for 

 existence, all the rest may be equally useless, an efflorescence 

 exhibited when there is friction due to lack of adjustment between 

 the organism and its environment. Finally, and most plausibly, 

 it may be argued that minds have evolved in answer to final causes, 

 and that organic evolution must adopt the principles of psycho- 

 logy rather than prescribe to it. 



The interactionist seems to be in a worse plight than the paral- 



