200 FROM FISH TO PHILOSOPHER 



Sherrington recognized— indeed, he himself went far 

 to establish— that 'mind' is utterly dependent upon the 

 most minute and detailed architecture and function of 

 the brain for its realization, at least as something recog- 

 nizable; and that it disappears, if not back into nihil, at 

 least into utter unrecognizabihty with the disintegration 

 of that brain. And yet, unable to see how *mind' could 

 be a manifestation of matter or energy, he was forced 

 to conclude that it could never be examined as a form of 

 either matter or energy. 



One thinks, however, that Sherringtons di£Bculty 

 arose in part from his persistence in the use of the word 

 'mind' in the Cartesian sense: as 'something that exists,' 

 in the sense in which matter and energy exist. Long ago 

 the philosopher David Hume defined miad' as an ab- 

 stract term denoting the series of ideas, memories, and 

 feelings which appear in consciousness, and which so 

 overlap that they give the impression of being continu- 

 ous, or of existing in a continuum. The lapse of two and 

 a half centuries has only served to aJBBrm Hume's defini- 

 tion, and there is no more warrant for speaking of this 

 temporal sequence as a 'thing' than of so describing the 

 sequence of flickering images that appear on the cinema 

 or television screen. In the concrete sense, we can only 

 speak of a particular image which momentarily appears 

 upon the screen— that is, in consciousness. It would be 

 well to drop the confusing word 'mind' from serious dis- 

 cussion. 



But we can speak of 'consciousness,' either as subjec- 

 tively perceived in ourselves or as inferred in others. Al- 

 though there are plenty of common-sense tests for de- 

 termining when a man is conscious or unconscious, an 

 adequate, objective definition of consciousness presents 

 considerable diflSculty. Consciousness is not an abstract 

 concept but a dynamic function of the organism in ac- 

 tion, in the same sense as the heartbeat, respiration, 

 muscular activity, or the excretion of urine. It cannot, 

 however, be defined merely as the capacity to respond 



