ween the
first and last is as regular and constant in those other cases as it is
in mine. In my own case I know that the first link produces the last
through the intermediate link, and could not produce it without.
Experience, therefore, obliges me to conclude that there must be an
intermediate link; which must either be the same in others as in
myself, or a different one. I must either believe them to be alive, or
to be automatons; and by believing them to be alive, that is, by
supposing the link to be of the same nature as in the case of which I
have experience, and which is in all respects similar, I bring other
human beings, as phenomena, under the same generalizations which I know
by experience to be the true theory of my own existence. And in doing
so I conform to the legitimate rules of experimental inquiry. The
process is exactly parallel to that by which Newton proved that the
force which keeps the planets in their orbits is identical with that by
which an apple falls to the ground. It was not incumbent on Newton to
prove the impossibility of its being any other force; he was thought to
have made out his point when he had simply shown that no other force
need be supposed. We know the existence of other beings by
generalization from the knowledge of our own; the generalization merely
postulates that what experience shows to be a mark of the existence of
something within the sphere of our consciousness, may be concluded to
be a mark of the same thing beyond that sphere."

Now, the plain man accepts the argument from analogy, here insisted
upon, every day of his life. He is continually forming an opinion as
to the contents of other minds on a basis of the bodily manifestations
presented to his view. The process of inference is so natural and
instinctive that we are tempted to say that it hardly deserves to be
called an inference. Certainly the man is not conscious of distinct
steps in the process; he perceives certain phenomena, and they are at
once illuminated by their interpretation. He reads other men as we
read a book--the signs on the paper are scarcely attended to, our whole
thought is absorbed in that for which they stand. As I have said
above, the psychologist accepts the argument, and founds his
conclusions upon it.

Upon what ground can one urge that this inference to other minds is a
doubtful one? It is made universally. We have seen that even those
who have theoretic objections against i