6 INTEODUCTION. 



higher, and even in that of men other than the sceptic 

 himself. For all objections which could apply to the use 

 of this criterion of mind in the animal kingdom would 

 apply with equal force to the evidence of any mind other 

 than that of the individual objector. This is obvious, 

 because, as I have already observed, the only evidence we 

 can have of objective mind is that which is furnished by 

 objective activities ; and as the subjective mind can never 

 become assimilated with the objective so as to learn by 

 direct feeling the mental processes which there accompany 

 the objective activities, it is clearly impossible to satisfy 

 any one who may choose to doubt the validity of inference, 

 that in any case other than his own mental processes ever 

 do accompany objective activities. Thus it is that philo- 

 sophy can supply no demonstrative refutation of idealism, 

 even of the most extravagant form. Common sense, how- 

 ever, universally feels that analogy is here a safer guide 

 to truth than the sceptical demand for impossible evi- 

 dence; so that if the objective existence of other or- 

 ganisms and their activities is granted — without which 

 postulate comparative psychology, like all the other 

 sciences, would be an unsubstantial dream — common 

 sense will always and without question conclude that the 

 activities of organisms other than our own, when analogous 

 to those activities of our own which we know to be accom- 

 panied by certain mental states, are in them accompanied 

 by analogous mental states. 



The theory of animal automatism, therefore, which is 

 usually attributed to Descartes (although it is not quite 

 clear how far this great philosopher really entertained the 

 theory), can never be accepted by common sense ; and even 

 as a philosophical speculation it will be seen, from what has 

 just been said, that by no feat of logic is it possible to 

 make the theory apply to animals to the exclusion of 

 man. The expression of fear or affection by a dog in- 

 volves quite as distinctive and complex a series of neuro- 

 muscular actions as does the expression of similar emotions 

 by a human being; and therefore, if the evidence of 

 corresponding mental states is held to be inadequate in 

 the one case, it must in consistency be held similarly 



