Dialectic and definition: Plato's Phaedrus 265c-266b

Dialectic is regarded as an important method of philosophy in Plato's later dialogues. Plato's Dialectic consists of two sub-methods, collection and division. Traditionally interpreted, collection and division are supposed to operate in combination to obtain the definition of anything under philosophical investigation, the former first determining the highest genus and the latter then dividing that into several species of lower levels. Plato's Phaedrus 265c-266b, however, presents a serious diffculty for this traditional interpretation, since the passage seems to imply that the method of collection by itself, independently of the method of division, can reach the definition. Hayase (Hayase 2016), who offers a new interpretation of Plato's Dialectic, rejects the traditional interpretation partly because of the diffculty of the passage. In this paper, having in view the argument of Hayase, I would like to show that actually the passage can consistently be understood on the traditional interpretation. Carefully examining the passage, we will see that although obtaining the definition is indeed said to be the objective of the method of collection, this by no means implies that collection by itself can achieve it. Socrates' statement about the importance of the definition, which immediately follows the introduction of collection, can be thought to be just a supplementary comment on the definition, not an illustration of collection, as Hayase assumes. Overall structure of the passage can be thought to be something like this: first, each of the two sub-methods is successively introduced, with a supplementary comment attached to the first of them, collection, and then follows the illustration of how they work together to get the definition. For the full evaluation of Hayase's new interpretation, we of course need much more thorough examination, but it is very important to see that the passage gives no diffculty to the traditional interpretation.