Hellenistic Philosophy Introductory

Introduction xvii
being which is pure form, by which he meant a form with no admixture
of matter whatsoever. Because substance in the sense of form was central
to Aristotle's theory of causal explanation (in that all four causes are
focussed on form) and to his metaphysics (in that the primary sense of
being was held to be a separate immaterial form, i.e., god or the Unmoved
Mover), a rejection of his doctrine of substance would entail the complete
abandonment of Aristotelian theoretical philosophy. The Epicureans and
Stoics clearly believed that a refutation of Aristotle's doctrines of causal
explanation and substance was inescapable.
The Epicureans and Stoics firmly and hard-headedly rejected incorpo-
real status for forms and for the soul. Direct evidence for rejection of
the Unmoved Mover is less abundant, but this is almost certainly a
result of the general rejection of the theory even among Aristotle's own
followers. Throughout the course of later Greek philosophy a philoso-
pher's stance on the incorporeality of forms and the soul served as a
doctrinal litmus test. Hence the thorough-going rejection of the incorpo-
real soul and non-material forms by these schools is a clear mark of their
'materialism' in the present sense.
This much, then, is novel with respect to Plato and Aristotle, though
the Epicureans and Stoics certainly had many predecessors who were
materialists in some sense. What distinguishes them from their predeces-
sors is, we think, the care with which they seem to have defended the
position against the anti-materialist arguments of Plato and Aristotle.
The empiricism of the Hellenistic schools is more complex. Certainly
it stands in sharp contrast to the epistemological stance of Plato; but
equally clearly it is a development of Aristotle's own rather tentative
empiricism. Aristotle believed, in the words of the scholastic tag, that
there was nothing in the mind which was not previously in the senses;
but he also held that his empiricist account of concept formation was
incomplete without a final stage required to render inductively derived
concepts sufficiently certain that they could serve as the basic principles
of the sciences. This reasonable belief, which shows a keen awareness of
the limitations of empirical procedures in grounding stable and irrefutable
knowledge, was rejected by the Hellenistic schools. Their empiricism,
consequently, is more thorough-going and also more vulnerable to
sceptical attack. It is tempting to see one stimulus for the rise of scepticism
in the rigour of Hellenistic empiricism.
In ethics the continuity of Hellenistic thought with Plato and Aristotle
is even more impressive. For here the key word is 'naturalism', which
represents the belief that a true conception of the good life for man must
be based on a clear and accurate conception of the nature of man. This
belief we take to have been the implicit position of pre-philosophical