A search for the factor, whatever it is, that distinguishes knowing from other states, has preoccupied
many philosophers, and preoccupies Plato, in changing form. In the early dialogues his concern is the
individual agent's understanding of what he is doing. Socrates picks on people whose reasons for acting
are second hand, picked up in an unreflective manner, who do not realize that tradition (even a good
one) if followed passively will leave one acting in a way which one does not oneself fully understand
and cannot defend. Ion, a famous performer of Homer, Laches, a brave general, Euthyphro, a religious
expert, and many others are brought to see that they do not really have any idea of why they act as they
do. The early dialogues arc in this respect variations on a single theme, and leave many dissatisfied,
since we get little indication as to what further we are to do. But possibly Plato thought that beyond this
there was nothing general to say, that once shorn of pretensions each person must achieve understanding
for and by himself. This fits well with a cryptic insistence in some early dialogues on the importance of
coming to know oneself. In the First Alcibiades the stage after the victim's conviction of his own lack of
knowledge is followed (132 ff.) by an exhortation to look at his own inner self, his soul, to find
understanding there. It is assumed without argument (in a way recalling Heraclitus) that each person
must achieve self-knowledge in his own case, that this self-knowledge amounts to the virtue of
sophrosyne, and that having this soundness of mind ensures that one will have a proper appreciation of
one's relations to others (indeed in the Lovers (138 b) it is identified with the virtue of justice).
The emphasis on self-knowledge as the basis of one's understanding of others is suggestive, but not
followed through. One reason can be found in the Char-mides, where discussion of self-knowledge
peters out because no coherent sense can be made of it. The problems seem to lie in the assumption that
knowledge must have an independent object, which 'self-knowledge', however interpreted, is unable to
provide; and the appearance of this assumption is of great importance. Concentration on individuals' self-
understanding turns out to have been a false start, and the model of attaining knowledge comes to be
quite different: a grasp of a systematic body of truths which is objective, independent of the individual
agent, and capable of being imparted.
In a famous passage in the Meno (82b-86c) Socrates takes a slave boy ignorant of geometry through a
proof, in such a way that he becomes able to see what the right answer is; he has become able to work
out for himself why the result must be the way it is. Socrates draws from this the optimistic conclusion
that knowledge is really 'recollection' of what our souls know already (hence, knew before our present
embodiment). Here we see clearly that knowledge involves having rational grounds in argument and
proof (so that it becomes unclear how we can have knowledge of something we simply find out from
experience, such as the road to Larissa). Plato has no doubt that such reasoning is objective; it reveals
what is really there, just as a geometrical proof does. And our reasoning capacity, identified -with the
soul, is sharply separated from our empirical means of cognition. The Phaedo develops this conception
in two ways. The soul, the reasoning ability which grasps reality, is even more drastically separated from
the body, understood as everything in us that is not pure reasoning. And Plato is more aware of the need
to systematize reasoning, making suggestive, but obscure, remarks about the organization and testing of
arguments (100 a, 101 d-e.)
In the central books of the Republic this model of knowledge, which clearly owes much to mathematics,