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 
