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 together, 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 produces 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 that the processes which go on in the
one are just like those which take place in the other. In the dog,
there can be no doubt that the nervous matter which lies between
the retina and the muscles undergoes a series of changes, precisely
analogous to those which, in the man, give rise to sensation, a train
of thought, and volition.

Whether this neurosis is accompanied by such psychosis as ours, it is
impossible to say; but those who deny that the nervous changes, which,
in the dog, correspond with those which underlie thought in a man, are
accompanied by consciousness, are equally bound to maintain that those
nervous changes in the dog, which correspond with those which underlie
sensation in a man, are also unaccompanied by consciousness. In other
words, if there is no ground for believing that a dog thinks, neither
is there any for believing that he feels.

As is well known, Descartes boldly faced this dilemma, and
maintained that all animals were mere machines and entirely devoid of
consciousness. But he did not deny, nor can anyone deny, that in this
case they are reasoning machines, capable of performing all those
operations which are performed by the nervous system of man when he
reasons. For even supposing that in man, and in man only, psychosis is
superadded to neurosis--the neurosis which