1. In his speculation on morals, no less than on knowledge,
Hume follows the lines laid down by Locke. With each
there is a precise correspondence between the doctrine of
nature and the doctrine of the good. Each gives an account
of reason consistent at least in this that, as it allows reason
no place in the constitution of real objects, so it allows it
none in the constitution of objects that determine desire and,
through it, the will. With each, consequently, the ‘moral
faculty’, whether regarded as the source of the judgments
‘ought and ought not,’ or of acts to which these judgments
are appropriate, can only be a certain faculty of feeling, a
particular susceptibility of pleasure and pain. The originality
of Hume lies in his systematic effort to account for those
objects, apparently other than pleasure and pain, which
determine desire, and which Locke had taken for granted with
out troubling himself about their adjustment to his theory,
as resulting from the modification of primary feelings by
‘associated ideas.’ ‘Natural relation,’ the close and uniform
sequence of certain impressions and ideas upon each other,
is the solvent by which in the moral world, as in the world
of knowledge, he disposes of those ostensibly necessary ideas
that seem to regulate impressions without being copied from
them; and in regard to the one application of it as much as
to the other, the question is whether the efficiency of the
solvent does not depend on its secretly including the very
ideas of which it seems to get rid.
2. The place held by the ‘essay concerning Human Understanding’, as a sort of philosopher’s Bible in the last century, is strikingly illustrated by the effect of doctrines that
