If we
are to avoid a perfectly gratuitous assumption, we must dispense with
the subject as one of the actual ingredients of the world. But when
we do this, the possibility of distinguishing the sensation from
the sense-datum vanishes; at least I see no way of preserving the
distinction. Accordingly the sensation that we have when we see a patch
of colour simply is that patch of colour, an actual constituent of the
physical world, and part of what physics is concerned with. A patch of
colour is certainly not knowledge, and therefore we cannot say that pure
sensation is cognitive. Through its psychological effects, it is the
cause of cognitions, partly by being itself a sign of things that
are correlated with it, as e.g. sensations of sight and touch are
correlated, and partly by giving rise to images and memories after the
sensation is faded. But in itself the pure sensation is not cognitive.

In the first lecture we considered the view of Brentano, that "we may
define psychical phenomena by saying that they are phenomena which
intentionally contain an object." We saw reasons to reject this view in
general; we are now concerned to show that it must be rejected in the
particular case of sensations. The kind of argument which formerly made
me accept Brentano's view in this case was exceedingly simple. When I
see a patch of colour, it seemed to me that the colour is not psychical,
but physical, while my seeing is not physical, but psychical. Hence
I concluded that the colour is something other than my seeing of
the colour. This argument, to me historically, was directed against
idealism: the emphatic part of it was the assertion that the colour is
physical, not psychical. I shall not trouble you now with the grounds
for holding as against Berkeley that the patch of colour is physical; I
have set them forth before, and I see no reason to modify them. But it
does not follow that the patch of colour is not also psychical, unless
we assume that the physical and the psychical cannot overlap, which I
no longer consider a valid assumption. If we admit--as I think we
should--that the patch of colour may be both physical and psychical, the
reason for distinguishing the sense-datum from the sensation disappears,
and we may say that the patch of colour and our sensation in seeing it
are identical.

This is the view of William James, Professor Dewey, and the American
realists. Perceptions, says Professor Dewey, are not per se cases of