back to the view of the vulgar, and this,
too, is admitted by Stewart so far as the cardinal doctrine of 'the
common sense' philosophy, the theory of perception, is admitted.

From this, again, it follows that the 'notions we annex to the words
Matter and Mind are merely relative.'[169] We know that mind exists as
we know that matter exists; or, if anything, we know the existence of
mind more certainly because more directly. The mind is suggested by 'the
subjects of our consciousness'; the body by the objects 'of our
perception.' But, on the other hand, we are totally 'ignorant of the
essence of either.'[170] We can discover the laws either of mental or
moral phenomena; but a law, as he explains, means in strictness nothing
but a 'general fact.'[171] It is idle, therefore, to explain the nature
of the union between the two unknowable substances; we can only discover
that they are united and observe the laws according to which one set of
phenomena corresponds to the other. From a misunderstanding of this
arise all the fallacies of scholastic ontology, 'the most idle and
absurd speculation that ever employed the human faculties.'[172] The
destruction of that pseudo-science was the great glory of Bacon and
Locke; and Reid has now discovered the method by which we may advance to
the establishment of a truly inductive 'philosophy of mind.'

It is not surprising that Stewart approximates in various directions to
the doctrines of the empirical school. He leans towards them whenever he
does not see the results to which he is tending. Thus, for example, he
is a thoroughgoing nominalist;[173] and on this point he deserts the
teaching of Reid. He defends against Reid the attack made by Berkeley
and Hume upon 'abstract ideas.' Rosmini,[174] in an elaborate criticism,
complains that Stewart did not perceive the inevitable tendency of
nominalism to materialism.[175] Stewart, in fact, accepts a good deal of
Horne Tooke's doctrine,[176] though calling Tooke an 'ingenious
grammarian, not a very profound philosopher,' but holds, as we shall
see, that the materialistic tendency can be avoided. As becomes a
nominalist, he attacks the syllogism upon grounds more fully brought out
by J. S. Mill. Upon another essential point, he agrees with the pure
empiricists. He accepts Hume's view of causation in all questions of
physical science. In natural philosophy, he declares causation means
only conjunction. The senses can never give us the 'effici