esistance to our grasp.
Thus we regard the whole group of sensations as due to the external
cause which produces the sensation of resistance. Brown seems to
hesitate a little as to whether he shall appeal to an 'intuition' or
to 'association,' but 'as I rather think,' he says, the belief is
founded 'on associations as powerful as intuition.'[487]

Whatever, then, may be the origin of the belief--'intuition' or
'association'--it is clear that it can give us no knowledge except
such as is derived from sensations. Moreover, Brown is thus led, as in
the doctrine of causation, to accept a really sceptical position. He
declares that he is in this respect at one with both Reid and Hume.
They both accept two propositions: first, that we cannot 'by mere
reasoning' prove the existence of an external world; secondly, that it
is 'absolutely impossible for us not to believe' in its existence.
Hume, he says, pronounces the first proposition in a 'loud tone
of voice' and 'whispers' the second. Reid, conversely, passes
over the first rapidly and 'dwells on the second with a tone of
confidence.'[488] Brown accepts both statements. He has already said
that there is no argument against Berkeley's denial of matter any more
than against the 'infinite divisibility of matter.' But he adds, it is
'physically impossible' for us to admit the conclusion, at least
without 'an instant dissent from a momentary logical admission.'[489]
This, indeed, is but a version of Hume's familiar statement that
Berkeley's arguments admit of no reply and produce no conviction.

Another essential doctrine of the Mills, the 'association' theory, is
treated differently by Brown. Brown, as we have seen, both in his
theory of causation and in his theory of our belief in an external
world, speaks of principles in the mind which somehow override
'ratiocination.' In the first case, he speaks of 'intuition,' but in
the other, as I have said, he seems to prefer association. The
difference is remarkable because the belief in an external world is
upon his showing simply a case of causation. It means essentially the
reference of our sensations as to an external cause. Now, in the
argument upon causation, he has insisted upon the insufficiency of
association to generate the belief; and he would have found it
difficult to meet his own arguments if applied to the belief in an
external world. Yet it does not seem to occur to him that there is any
difficulty in explaining this b