From the Beginning to Plato

206 ANAXAGORAS AND THE ATOMISTS
These renderings are, however, very unlikely. The majority of the sources follow
Aristotle (On the Generation of Animals 789b 2–3, DK 68 A 66) in asserting that
Democritus denied purposiveness in the natural world, explaining everything by
mechanistic ‘necessity’. 3 A reading of Leucippus which has him assert, not
merely (contra Democritus) that some, but that all natural events are purposive,
posits a dislocation between the fundamental world-views of the two of such
magnitude that we should expect it to have left some trace in the tradition.
Moreover, the attribution of all events to necessity, a central feature of the
mechanistic Democritean world-view, is itself attested in the fragment of
Leucippus. We ought, then, to look for an interpretation of the fragment which
allows it to be consistent with Democritus’ denial of final causation.
Such an interpretation is available without forcing the texts. Sometimes (e.g.
Herodotus VII.103.2, Plato Theaetetus 189d) matēn is to be rendered not ‘without
purpose’ but ‘without reason’ (‘in vain’ and ‘empty’ have similar ranges of
application). Given that construal of matēn, ‘from reason’ is to be construed as
‘for a reason’, where the conception of reason is linked to that of rational
explanation. The first part of the fragment (‘Nothing happens at random, but
everything from reason’) thus asserts, not universal purposiveness in nature, but
a principle which we have already seen to be pervasive in atomism, the Principle
of Sufficient Reason. Instead of a radical discontinuity between Leucippus and
Democritus, the fragment, thus construed, attests commitment to a principle
basic to atomism. The second half (‘and by necessity’) makes a stronger claim,
which links the notion of rational explanation to the notions of necessity and of
cause. The stronger claim is that whatever happens has to be happen, cannot but
happen. This amounts to a specification of the reason whose existence is asserted
in the first half of the sentence; nothing happens without a reason, and, in the
case of everything which happens, the reason for which it happened was that it
had to happen. But the claim that whatever happens happens ‘by necessity’ is not
just the claim that whatever happens has to happen, though the former implies
the latter. For the concept of necessity is not a purely modal concept requiring
elucidation via its connection with other such concepts, such as possibility and
impossibility. Rather, necessity is conceived as an irresistible force bringing it
about that things have to happen. This is indicated both by the causal force of the
preposition hypo (rendered ‘by’ in the expression ‘by necessity’), and also by the
fact that Democritus is reported as identifying necessity with impact and motion
((Aetius I.26.2, DK 68 A 66) on the interpretation of this see below). Impact and
motion, then, take over the determining role traditionally assigned to Necessity,
when the latter is conceived (as in Parmenides and Empedocles) as an
ineluctable, divine cosmic force (cf. Plato, Protagoras 345d5 ‘Against necessity
not even the gods fight’).
Nothing, then, just happens; every event occurs because it had to occur, i.e.
because it was made to occur by prior impact (namely, of atoms on one another)
and prior motion (namely, of atoms). So there can be no chance events, i.e. no
events which simply happen. On the other hand, we have evidence that the