32 Chapter III. 



sitions, and the differences of the sense perceptions that 

 arouse individual instinctive impulses. Hence it is that 

 specific uniformity forms only a changeable and by no 

 means essential characteristic of instinctive actions. 

 We may indeed state, that those manifestations of 

 psychic life in animals which are performed by all 

 members of a species according to hereditary laws and 

 without previous experience in a constant and uniform 

 manner are certainly due to instinct and not to intelli- 

 gence; but we are not allowed to invert the proposition 

 and say that only those manifestations of psychic life 

 in animals are instinctive which are performed by all 

 members of a species according to hereditary laws, and 

 without previous experience in a uniform manner, whilst 

 all the rest are intelligent. Such an inversion would be 

 false logic; for its legitimacy must first be proved. 

 Yet, neither Ziegler nor Romanes nor any modern 

 psychologist has ever demonstrated that only the 

 hereditary and the specifically uniform psychic activities 

 of animals are of an instinctive nature. 



Very different, however, is the distinctive character 

 which we have established. It alone holds good, exclu- 

 sively of any other. For we are not only allowed to 

 say : Those spontaneous actions must be regarded as 

 instinctive in which the agent is not conscious of the 

 purpose of the act, but we have proved that only these 

 actions must be considered as instinctive, whilst the rest 

 are intelligent. Consequently we can express the cri- 

 terion of instinct and intelligence in the following man- 

 ner: only those spontaneous actions of animals are to 

 be called intelligent in which consciousness of the end 

 can be proven, all the rest have to be regarded as in- 



