From the Beginning to Plato

FROM THE BEGINNING TO PLATO 349
merely sensible phenomena, will ultimately be explained by reference to the
Form of the Good (Republic 509b).
Later, the Timaeus identifies the contrast between ideological and mechanical
explanations of features of the sensible world with a contrast between Reason
and Necessity, and now some things are explained by one factor, some by the
other, and some by both. Reason has priority over Necessity, acts to produce
what is best and is solely responsible for anything that is intrinsically good such
as order and proportion. At the cosmic level it is represented by the ‘Demiurge,’
the creator who looks to the Forms and tries to embody them in disorderly
matter. Necessity is responsible for randomness, disorder and evil in the material
world, but also acts in subordination to Reason to explain features which are
necessary conditions for and concomitant causes of certain instrumental goods,
much like Socrates’ bones and sinews in the Phaedo (99a). 57
In later dialogues 58 dialectic involves less argumentation and greater interest in
classification. The Republic’s conception of a master science establishing the
starting-points of subordinate disciplines disappears, and is apparently not
required for understanding an area of enquiry. For all Plato explicitly says,
distinct disciplines are now autonomous. The procedure called ‘collection and
division’ does not provisionally posit a hypothesis and then subject it to critical
scrutiny. Rather, it standardly begins when undefined species are unified under a
defined genus. This genus is divided into species, which are in turn divided into
subspecies, etc., until indivisible species are reached. Conjoining the divisions
thus passed through yields definitions of the items at the end of the chains.
Dichotomy—the division of a genus into two species—may be followed when the
aim is to define a particular Form, since the remaining species will then be
irrelevant. But when we want clarification of a genus the number of divisions
made at any stage should match the natural, objective divisions in the subjectmatter.
However, collection and division does not exhaust the content of Plato’s later
‘dialectic’. It comprises (Sophist 253b–d):
1 dividing things according to Kinds;
2 producing definitions of Forms;
3 not identifying distinct Forms or distinguishing identical Forms;
4 knowing what Forms can and cannot combine.
(1) often aims at (2), and the misidentification of distinct Forms (violating (3)) may
result from failure to properly divide a genus (cf. Politicus 285a). But that is not
how misidentification of the Greatest Kinds is avoided in the Sophist (254b–
257a), nor is it obvious how (4) is connected with division. Sophist 254bf. aims
for (3) and (4) but uses arguments characteristic of the earlier dialectical method,
and makes no use of the sorts of divisions which occur at the beginning of the
dialogue. Perhaps Plato thought that when, unlike with many of his own