What is Intelligence, and What is Instinct? 39 



philosophy ascribed to the animal a sensile memory 

 (memoria sensitiva), and a power of perfecting inborn 

 instincts through sense experience (expectatio casuum 

 similium) ; it acknowledged in the animal not only 

 complete hereditary talents for certain activities, but to 

 a certain degree talents and abilities acquired by sense 

 experience and by practice (habitus acquisiti). 1 Hence 

 in stating that the animal was guided merely by its 

 natural instinct, scholasticism apparently used the term 

 instinct in our broader meaning. 



The previous discussions make it evident that in- 

 stinctive life in reality coincides with sensitive, whilst 

 intelligence is identical with mental life. Instinct sig- 

 nifies the peculiarity of the powers of sensitive cognition 

 and appetite, whilst intelligence expresses the peculiarity 

 of the mental power of cognition and stands in insepar- 

 able relation to free volition, the corresponding mental 

 power of the spiritual appetite. Consequently the ques- 

 tion, whether animals possess intelligence as well as 

 instinct, is, in reality, identical with the other: Do ani- 

 mals possess a mental, besides a sensitive, life? 



In modern animal psychology the term "mental fac- 

 ulties" has been grossly misapplied. The tendency of 

 materialism which is to obliterate as much as possible 

 the differences between the animal psyche and the hu- 

 man mind has led to the denial of essential differences 

 between sensile and spiritual faculties. It ignores the 

 rules of critical analysis. Moreover the modern theory 

 of evolution which demands the "natural" development 

 of man from the animal as a "postulate of science," has 



See S. Thomas, "Summa theol.," 1, 2, q. 50, a. 3 ad 2. 



