CONCEPTUAL THOUGHT 159 



learned behavior was an immensely promising step, but not 

 necessarily the final step that must be taken. 



The most recent studies of learning in animals, especially 

 in the primates, have been so designed as to bring out the 

 capacity which the psychologists call concept formation. 

 By and large this term would involve no more than the abil- 

 ity to generalize to a particular characteristic of stimuli 

 varying in multiple ways (examples will follow)— an ability 

 that can be demonstrated in animals even below the level of 

 the mammals. Psychologists usually, however, make a dis- 

 tinction at the level of man which postulates a symbolizing 

 (or language) process as necessary to conceptual thought. 

 There is considerable difference of opinion as to how fine 

 this distinction should be drawn. In a very narrow sense 

 linguistic responses are limited or doubtful in any animal 

 other than man. Nissen in his review of the situation points 

 out that it may be more proper to look at language as a 

 symptom or indicator of symbolism, not its necessary con- 

 dition. In this case degrees of conceptual thought can be 

 demonstrated in many animals, the bees and rats and mon- 

 keys and apes, at least. Psychologists would be in agreement 

 with the statement that conceptual thought does not appear 

 suddenly at the level of man but must be anticipated by in- 

 gredients which are increasingly present in forms below his 

 level. 



Early philosophers suggested that the mind developed 

 merely through an idea-and-experience association, but it 

 has been apparent for the past century that this was not an 

 adequate explanation. John Locke had discarded the as- 

 sumption, supported particularly by theologians, that ideas 

 (faith and morals, for instance) were inborn and categori- 

 cally declared that all our knowledge came from experience 

 and through the senses— "nothing in the mind except what 

 was first in the senses." Some modern philosophers and 

 psychologists suggest that the brain is not passive in learning 

 but develops organizations which facilitate the process. 



