2. Supporters. Nothing of great moment was added
to the moral sense theory by writers subsequent to
Hume who gave it their support. This may be illus-
trated by a glance at Hartley and Kames.
David Hartley's Observations on Man (1749) is
important for working out in detail a scheme of psy-
chology based on the association of ideas. Hartley's
thoughts on the subject were first stimulated by the
remarks of Gay in the Dissertation mentioned above,
but Hartley does not follow Gay in reducing morality
to self-interest. He regards the moral sense as the effect
of associating pleasure with virtue, and pain with vice,
from several different sources: education, self-interest,
sympathy, aesthetic feeling, and religious doctrine.
Hartley therefore disagrees with Hutcheson's notion
of the moral sense as an original “instinct,” but his
account of its formation is too vague to be enlightening.
Hume's kinsman, Henry Home, Lord Kames, pre-
sents himself as a supporter of the moral sense theory
in his Essays on the Principles of Morality and Natural
Religion (1751). He follows Shaftesbury, Hutcheson,
and Hume in comparing the moral sense with aesthetic
feeling, but criticizes all three of them for giving
inadequate attention to the ideas of duty and obliga-
tion, which he, like the rationalists, regards as the
central concepts of morality. When Kames enlarges
upon the “perception” of duty and justice, he writes
more in the vein of traditional natural law doctrine
than of the empiricist approach to ethics.
