v MR. DARWIN'S CRITICS 159 



psychosis vanish, and the loosing of the dog follows 

 unconsciously, or as we say, without thinking about 

 it, upon the sight of the hare. No one will deny 

 that the series of acts which originally intervened 

 between the sensation and the letting go of the 

 dog were, in the strictest sense, intellectual and 

 rational operations. Do they cease to be so when 

 the man ceases to be conscious of them ? That 

 depends upon what is the essence and what the 

 accident of those operations, which, taken to- 

 gether, constitute ratiocination. 



Now ratiocination is resolvable into predication, 

 and predication consists in marking, in some way, 

 the existence, the co-existence, the succession, the 

 likeness and unlikeness, of things or their ideas. 

 Whatever does this, reasons ; and if a machine pro- 

 duces the effects of reason, I see no more ground 

 for denying to it the reasoning power, because it 

 is unconscious, than I see for refusing to Mr. 

 Babbage's engine the title of a calculating machine 

 on the same grounds. 



Thus it seems to me that a gamekeeper reasons, 

 whether he is conscious or unconscious, whether 

 his reasoning is carried on by neurosis alone, or 

 whether it involves more or less psychosis. And 

 if this is true of the gamekeeper, it is also true of 

 the greyhound. The essential resemblances in all 

 points of structure and function, so far as they can 

 be studied, between the nervous system of the man 

 and that of the dog, leave no reasonable doubt 



