empiricism to build the human sciences, where he expected the rewards to be
even greater than in the natural sciences (Mossner, 1954; Passmore, 1980;
Greig 1932). Book 1 of his Treatise of Human Nature (1739), containing
Hume’s philosophically fateful criticism of causality and of the identity of the
self, is merely preliminary, laying the foundations of a science of human
understanding; the payoff comes in the later books, comprising a psychology
of human motivation, a science of morality (1739–40) followed by a science
of aesthetic taste and of human societies. The last two never appeared as such,
but Hume did go on to write his theory of economics (1752) and his History
of Great Britain (1754–1762), which contained the essence of his political
theories and established his contemporary fame.
Hume inadvertently occupies philosophical turf in formulating a program-
matic statement as the basis for the moral sciences. He begins with the principle
of empiricism—"all of our ideas are copied from our impressions"—(Treatise
76) and argues deductively for its consequences. Hume purifies the empiricist
tendency of his predecessors, allowing no other source of logic or of ideas than
our experience of sensory impressions. He critiques all previous metaphysical
positions. He allows neither material substances behind the phenomenal flux
nor any immaterial substance; Cartesian dualism, Spinoza’s monism, Male-
branche’s occasionalism, Newtonian space, abstract ideas, and primary quali-
ties distinct from secondary qualities all go down under the critique. So do the
certainty of mathematics, the necessity of causes, the identity of the self, and
implicitly the nature of the soul and any argument for the existence of the
Deity. Hume’s main positive doctrine, the principle of the association of im-
pressions by which the human mind builds up its habitual ideas, is itself a
philosophical argument rather than a result of empirical investigations. His
program makes his moral science superior to the natural sciences; indeed it
becomes their basis, for it is the psychological law of association which is “the
cement of the universe” (Abstract 32; see Passmore, 1980: 105) rather than
an externally existing causality or a freestanding mathematics.
Why should it be someone like Hume who took this step? Hume was part
of an intellectual movement, the Scottish Enlightenment, which ran through
Adam Smith to Ferguson, Millar, and Stewart. The other Scots shared Hume’s
program for building the human sciences, and laid the basis for fields such as
economics, sociology, and archaeology. For the most part they occupied spe-
cialized empirical turfs, and had neither Hume’s creativity in philosophical
issues nor his radical skepticism; nor were they generally as extreme as Hume
in making the natural sciences subservient to moral science. One significant
difference is that Hume came at the very beginning of this movement, writing
his Treatise during 1734–1737, and it was the earliest part of his writings that
formulated his philosophy and his metaphysical critique. Hume had the first
glimpse of a new intellectual field opening up, the autonomous moral sciences,
614 • (^) Intellectual Communities: Western Paths