go deeper into the distinction than logicians.
Substances, most of them say, are either bodies or minds; and, of these,
a body is the external cause to which we ascribe sensations. Berkeley
and the Idealists, however, deny that there exists any cause of
sensations (except, indeed, a First Cause). They argue that the _whole_
of our notion of a body consists of a number of our own or others'
sensations occurring together habitually (so that, the thought of one
being associated with the thought of the others, we get what Hartley and
Locke call a complex idea). They deny that a residuum would remain if
all the attributes were pared off; for that, though the sensations are
bound together by a law, the existence of a _substratum_ is but one of
many forms of mentally realising the connection. And they ask how it
is,--since so long as the sensations occurred in the old order, we
should not miss such a _substratum_, supposing it to have once existed
_and to have perished_--that we can know it exists even now? Their
opponents used formerly to reply, that the uniform order of sensations
implies an external cause determining the law of the order; and that the
attributes _inhere_ in this external cause or substratum, viz. matter.
But at last it was seen that the existence of matter could not be proved
by extrinsic evidence; consequently, now the answer to the idealist
argument simply is, that the belief in an external cause of sensations
is universal, and as intuitive as our knowledge of sensations
themselves. Even Kant allows this (notwithstanding his belief in the
existence of a universe of _things in themselves_, i.e. Nouemena, as
contrasted with the mental representation of them, where the sensations,
he thinks, furnish the matter, and the laws of the mind, the form).
Brown even traced up to the sensations of touch, combined with the
sensations seated in the muscular frame, those very properties, viz.,
extension and figure, which Reid referred to as proving that some
qualities must exist, not in the sensations, but in the things
themselves, _since_ they cannot possibly be copies of any impression on
the senses. We have, in truth, no right to consider a thing's sensible
qualities akin to its nature, unless we suppose an absurdity, viz. that
a cause must, as such, resemble its effects. In any case, the question
whether Ontology be a possible science, concerns, not Logic, but the
nature and laws of intuitive knowledge. And the questi