474 GENERAL CONSIDERATIONS 



ment. A spider defending its egg cocoon is actuated by an instinct and 

 not by love. 



Pain and pleasure do not seem to be felt by animals which have little 

 or no intelligence. An injured dog will cry out in pain, loses its appetite, 

 and in some cases seems to suffer as much from an injury as does a human 

 being. Fish, however, after having been caught on a hook and then 

 liberated with their mouths severely mutilated have been known to bite 

 again immediately, as if feeling no pain from the wounds. Numbers of 

 cases might be cited of similar insensibility to pain on the part of nonintel- 

 ligent or slightly intelligent animals. In the same way pleasure seems to 

 be associated with intelligence. 



The only way to determine whether or not an animal is intelligent is 

 to place it under experimental conditions. Then if it shows an ability 

 freely to modify its behavior and this modification is in such a direction 

 as to imply an appreciation of cause and effect, we may term the behavior 

 intelligent. It is clear that intelligent behavior can never be stereotyped, 

 and it is equally clear that intelligent acts cannot be inherited, although 

 the quality of intelligence is, 



524. Reasoning. — Theoretically it may be possible to draw a distinc- 

 tion between reasoning and intelligence, but practically such a distinction 

 is difficult to apply. Perhaps the most obvious difference is that reason- 

 ing involves the ability on the part of an animal to form an abstract 

 conception and be guided in action by it. An animal which after having 

 had a certain experience successfully meets the same conditions when they 

 occur again does not thereby evidence a power to reason; but if he so 

 adjusts the results of a previous experience as to meet conditions some- 

 what different, this would seem to imply an ability to reason to the 

 degree that differences exist between the two experiences. Reason 

 enables an animal to meet conditions which it has never met before by 

 the perception of analogies between them and conditions connected with 

 previous experiences. Many stories are told of dogs, horses, and other 

 mammals which seem to imply the ability to reason on their part. The 

 capacity to dream may be taken as implying the ability to form abstract 

 conceptions and as an evidence of the power to reason. Numerous 

 instances of dreaming on the part of domestic animals have been recorded. 

 Reasoning does not seem to have ever been attributed to animals other 

 than the higher mammals, and in no other mammal is it so highly devel- 

 oped as it is in man. There is a tremendous gap between the reasoning 

 capacity of the savage and that of the highly civilized man, but even the 

 savage seems to be raised so far above other mammals by his capacity to 

 reason that man as a type has been characterized as the reasoning 

 animal. 



525. Combinations of Modes of Behavior. — It is clear from what has 

 been said that the actions of an animal may be the result of a combina- 



