INSTINCT AND INTELLIGENCE. 653 



mSTINCT AND mXELLIGENCE.' 



By Prof. JOSEPH LE CONTE. 



WHAT is instinct? What is its relation to intelligence? These 

 questions form the subject of my lecture to-day. 



Many persons would probably object to this subject being treated 

 at all in a course of physiology. Many persons doubtless think that 

 these are questions for the psychologist, and not for the physiologist. 

 But I think you have already perceived, in the course of these lect- 

 ures, how difficult, yea, impossible, it is to sharply separate these two 

 departments. As between all other departments of science, so also 

 between these, there is a border-land, which is common ground. The 

 physiology of the brain is that common ground. 



The precise relation of physiology to psychology it is extremely 

 difficult to adjust. As there are two opposite errors in regard to vital 

 force one, the old error of regarding this force as something innate, 

 underived, unrelated to other forces of Nature ; the other, the new 

 error of regarding it as nothing but ordinary physical and chemical 

 forces, and thus identifying physiology with chemistry and physics 

 so also on this subject there are two opposite errors : one the old 

 error of regarding mental forces as wholly unrelated to and underived 

 from vital forces, and psychology, as wholly disconnected from physi- 

 ology ; the other, the new error of regarding mental phenomena as 

 connected with the brain in the same clear and intelligible way that 

 functions are connected with organs, and thus identifying psychology 

 with physiology. But, as in the case of vital force, there is a truer 

 view, viz., that which regards this force as indeed correlated with 

 other lower forces and derived from them, but, nevertheless, as a very 

 distinct /orm of force or cosmic energy, producing a very distinct and 

 peculiar group of phenomena, the knowledge of which constitutes the 

 science of physiology ; so also, on the subject of mental force, there is 

 a truer view which comprehends and embraces the extremes men- 

 tioned above. 



Let me briefly explain my views on this subject. In recent times 

 physiology has indeed made great, and to many startling, advances in 

 the direction of connecting mental phenomena with brain-changes. 

 Physiologists have established the correlation of physical and chemi- 

 cal with vital forces, and probably of vital with mental forces. They 

 have proved in every act of perception the existence of a vibratory 

 thrill passing along the nerve-cord from sense-organ to brain ; and in 

 every act of volition a similar vibratory thrill from brain to muscle ; 

 they have even determined the velocity of this vibratory thrill, and 

 find it, to the surprise of those who identify nervous force with elec- 

 ' A Lecture to the Class in Comparative Physiology in the University of California. 



