INTRODUCTION 7 



explaining one. But a discussion of this question in all its 

 bearings would carry us too far. 



If there is no infallible test for the determination of the 

 existence of consciousness in animals we are by no means led, 

 as some physiologists would have us believe, to the denial 

 of the possibility of a comparative psychology. If we can 

 explain the behavior of lower organisms in terms of phy- 

 siological laws without assuming any role of conscious states 

 in determining their acts, and were able to extend the same 

 kind of explanation to higher forms until ultimately the 

 whole sentient creation were embraced in our system, the 

 rejection of comparative psychology would logically lead, 

 as Claparede thas well shown, to the denial of human psy- 

 chology as well. On the other hand, starting in with the 

 assumption that human psychology is a legitimate subject 

 matter for a science, there is no logical ground for refusing 

 to draw inferences concerning the mental aspects of the 

 behavior of apes, and other higher mammals; and if we 

 can infer something of the mental life of the animals near- 

 est ourselves we are warranted in extending our psycho- 

 logical inferences as far down in the scale as analogy per- 

 mits us to go. How far analogy warrants us in going 

 is capable of but a very indefinite answer. When we 

 come to ants and spiders everyone may perhaps be allowed 

 to have his own opinion; and there may be a more than 

 sufficient compensation for our inability to reach conclu- 

 sive proofs of our views regarding the psychic life of such 

 creatures in having a perennial source of contention with 

 which comparative psychologists may occupy themselves 

 whenever they come together. 



The existence of mind in the lower animals has something 

 more than a theoretical interest. In our experiments on 

 these creatures it would be unfortunate if we were mistaken 



