ich we can ascertain
what other people "know," is a phenomenon exemplified in their physical
behaviour, including spoken and written words. There is no reason--so
Watson argues--to suppose that their knowledge IS anything beyond the
habits shown in this behaviour: the inference that other people
have something nonphysical called "mind" or "thought" is therefore
unwarranted.

So far, there is nothing particularly repugnant to our prejudices in the
conclusions of the behaviourists. We are all willing to admit that
other people are thoughtless. But when it comes to ourselves, we feel
convinced that we can actually perceive our own thinking. "Cogito, ergo
sum" would be regarded by most people as having a true premiss. This,
however, the behaviourist denies. He maintains that our knowledge of
ourselves is no different in kind from our knowledge of other people.
We may see MORE, because our own body is easier to observe than that of
other people; but we do not see anything radically unlike what we see
of others. Introspection, as a separate source of knowledge, is entirely
denied by psychologists of this school. I shall discuss this question at
length in a later lecture; for the present I will only observe that
it is by no means simple, and that, though I believe the behaviourists
somewhat overstate their case, yet there is an important element of
truth in their contention, since the things which we can discover by
introspection do not seem to differ in any very fundamental way from the
things which we discover by external observation.

So far, we have been principally concerned with knowing. But it might
well be maintained that desiring is what is really most characteristic
of mind. Human beings are constantly engaged in achieving some end
they feel pleasure in success and pain in failure. In a purely material
world, it may be said, there would be no opposition of pleasant and
unpleasant, good and bad, what is desired and what is feared. A man's
acts are governed by purposes. He decides, let us suppose, to go to a
certain place, whereupon he proceeds to the station, takes his ticket
and enters the train. If the usual route is blocked by an accident,
he goes by some other route. All that he does is determined--or so it
seems--by the end he has in view, by what lies in front of him, rather
than by what lies behind. With dead matter, this is not the case.
A stone at the top of a hill may start rolling, but it shows no
pertina