1 8 MIND IN EVOLUTION CHAP. 



tion of behaviour can prove that it is so in another. This 

 criticism we must provisionally accept. What our reason- 

 ing can prove is that the operation of Mind is implicated 

 in certain forms of correlation, and it is on this ground 

 that for the time being we call them mental. The proof 

 that Mind is the operative cause must rest on the analysis 

 of the nature of mechanism on the one hand and of mental 

 causation on the other. For our present purposes the 

 names mechanical and mental must be held to import, the 

 one correlation corresponding to that of known machines 

 and not involving mental activity, the other correlation 

 involving mental activity and radically different from 

 that of known machines. Secondly, in imputing a specific 

 mode of consciousness to another we argue from the 

 situation and the behaviour. If these were in all respects 

 similar from case to case, there would be no difficulty. 

 But no two situations are absolutely alike. If we argue 

 from our own behaviour in one case to that of another 

 person in his case, we are justified only if the cases 

 are alike in all relevant points. What is relevant we 

 decide, as in all induction, by comparison of instances 

 wherein those things which go uniformly together are 

 distinguished from those which vary independently. But 

 now when we come to beings which differ permanently 

 from ourselves, a graver difficulty is introduced. This 

 difficulty appears even in human psychology in our judg- 

 ments of the other sex or of another race, even of another 

 class or another age than our own. It is still more serious 

 when we are dealing with animals whose whole organisa- 

 tion presents points of difference from ours, who are 

 relatively poor in means of expression, and whose behaviour 

 does not therefore afford so many opportunities for test- 

 ing a doubtful point. The attribution of consciousness 

 to animals rests ultimately on the same logic as its 

 attribution by you or me to our fellow men. But the 

 differences which already give us trouble in judging our 

 fellows are deeper, and the tests by which we may measure 

 their effect more difficult to apply. But this at least we 

 can say : if the behaviour of another being corresponds 

 precisely in all its outer relations to that which I know of 



