In the Phaedrus Plato speaks about a new method, or at least speaks in a new way about an old method, that he and presumably his master Socrates, had been practicing in their philosophical inquiries. It is known as the Method of Collection and Division.[21] If you want to understand something you are studying, you will need to define it, Socrates always insists. But as readers of Socratic dialogues should know, defining a subject is not at all easy. Socrates typically seems to test proffered definitions by seeing if they are consistent with other beliefs the interlocutor has.
In the Phaedrus, however, Plato’s Socrates seems to focus on a kind of method preliminary to offering a definition. You should, he says, collect diverse examples of the thing you are studying into one class (idea), so as to make the object concerning which you wish to teach clear by definition.[22] For instance (though, unfortunately, Plato does not offer any instances at first), if you wanted to define courage, you should survey situations in which a person, or an action of a person, is said to be courageous.
Secondly, you “should again divide [the class] into kinds at their natural joints” like a good butcher preparing cuts of meat.[23] The assumption is that when you collect and divide instances of a certain type, there is a natural class of them all, and that below that there are natural subclasses as well. The approach here seems to invite an induction from particular instances to produce a general class. Plato had at least envisioned the movement of hypotheses from the less general to the more general in his Divided Line analogy in Republic Book 6.[24] But in other dialogues we have never seen Plato showing any interest in a kind of empirical approach that proceeds from particulars to properties and Forms. Here, he seems to endorse a bottom-up approach, at least as a preliminary stage of understanding what things there are. Plato identifies those who are best able to conduct studies of collection and division as dialecticians (dialektikoi).[25]
Plato’s Socrates goes on to talk about the parts of a speech, not quite making it clear whether this is an application of the new method. Socrates then cites the practice of Hippocratic medicine as a model of good scientific procedure. As medicine seeks to understand and benefit the body, so the art of speaking, properly understood, should seek to understand and benefit the soul.[26] The art of medicine, as understood by Hippocrates, seeks to study the body, its nature and powers, and subdivides it as needed to study the nature and powers of the organs and body parts.[27]
Similarly, the orator should understand the soul and its capacities, including the types of soul, and how to benefit each type. In effect, Plato seems to say, the real orator must be not only a student of speech but also a psychologist who knows how to communicate with each type of person in the audience, so as to provide persuasion as a kind of therapy to that person.[28] Oratory will be an applied science and the orator a trained therapist. Presumably, the ideal orator will not have to tailor the message to each individual in the audience (an impossible task), but rather to provide the proper stimulus for every type of personality, so that all will be persuaded by one technique or another.
In passing, Plato makes mention of the need for the scientific orator to study Nature as a whole, so as to appreciate the place of soul and other factors that influence communication between speaker and audience. The remarks about the Method of Collection and Division and its connections to Nature as a whole and the practice of natural philosophy and medicine could have been just an interesting sidelight. But, as we shall see, here at the end of Plato’s Middle Period going into his Late Period, Plato is becoming less other-worldly and more interested in the here and now. His ultimate realities will look less like transcendent Forms and more like classes of individuals; the Forms will at least correspond to classes of physical objects that can be captured by conceptual maps and Venn diagrams. And Plato will appear less visionary and more scientific.
[21] Plato Phaedrus 266b3-4.
[23] Plato Phaedrus 265e.
[24] Plato Republic 510b; 511b.
[25] Plato Phaedrus 266b-c.
[26] Plato Phaedrus 270b.
[27] Plato Phaedrus 270c-d.
[28] Plato Phaedrus 270e-272a.