s? The question will keep coming back again: May there not, after
all, be a legitimate doubt on the subject?

To set this question at rest there seems to be only one way, and that
is this: to ascertain the nature of the inference which is made, and to
see clearly what can be meant by _proof_ when one is concerned with
such matters as these. If it turns out that we have proof, in the only
sense of the word in which it is reasonable to ask for proof, our doubt
falls away of itself.

41. THE ARGUMENT FOR OTHER MINDS.--I have said early in this volume
(section 7) that the plain man perceives that other men act very much
as he does, and that he attributes to them minds more or less like his
own. He reasons from like to like--other bodies present phenomena
which, in the case of his own body, he perceives to be indicative of
mind, and he accepts them as indicative of mind there also. The
psychologist makes constant use of this inference; indeed, he could not
develop his science without it.

John Stuart Mill (1806-1873), whom it is always a pleasure to read
because he is so clear and straightforward, presents this argument in
the following form:[3]--

"By what evidence do I know, or by what considerations am I led to
believe, that there exist other sentient creatures; that the walking
and speaking figures which I see and hear, have sensations and
thoughts, or, in other words, possess Minds? The most strenuous
Intuitionist does not include this among the things that I know by
direct intuition. I conclude it from certain things, which my
experience of my own states of feeling proves to me to be marks of it.
These marks are of two kinds, antecedent and subsequent; the previous
conditions requisite for feeling, and the effects or consequences of
it. I conclude that other human beings have feelings like me, because,
first, they have bodies like me, which I know, in my own case, to be
the antecedent condition of feelings; and because, secondly, they
exhibit the acts, and other outward signs, which in my own case I know
by experience to be caused by feelings. I am conscious in myself of a
series of facts connected by a uniform sequence, of which the beginning
is modifications of my body, the middle is feelings, the end is outward
demeanor. In the case of other human beings I have the evidence of my
senses for the first and last links of the series, but not for the
intermediate link. I find, however, that the sequence bet