プラトン『パイドン』における形相原因説

Abstract

This article addresses itself to two central and fundamental interpretative problems concerning the thesis of forms as causes, which consists of the form hypothesis and the participation hypothesis, as put forward by Socrates in Phaedo 100b1-e4. The first problem is concerned with the ontological status of forms, or Forms as it is usually written by scholars, and the second with the meaningfulness of this thesis. First, there has been continuing disagreement among scholars about the ontological status of forms/Forms. Some scholars (separationists) claim that Forms are purely separate from perceptible things, as evidenced by e.g. Symposium 211a1-b3. Others (immanentists) claim that Forms can somehow be immanent in perceptible things, as evidenced by e.g. Phaedo 100d4-7 and Republic 476a5-8. The immanentists regard largeness in Simmias mentioned in 102b5-6 as a Form, while the separationists regard it as an immanent character or Form-copy, which is perceptible. My diagnosis of this interpretative cul-de-sac is that the monolithic understanding of forms is at fault. I propose that Socrates originally conceived of forms as a broad concept which includes two ontologically different kinds of intelligible entities, i.e. those exiting by themselves (or the true beings, τό όντως όν) and those existing in connection with things, actions, and situations (which are at issue in the so-called definitional dialogues and the method of collection and division). I argue that this interpretation can explain Plato's presentation of the thesis of forms as causes consistently throughout, including evidence brought forward by both the separationists and the immanentists. As for the second problem, many scholars believe that the participation hypothesis (that any x is F because it participates in F-ness) is tautological or uninformative, and attempts proposed to explain its significance seem to me to have been unsuccessful. I myself call attention to the fact that it is a philosophically significant decision to assume that, for example, any kind of beautiful thing, be it a person or a mathematical formula, is beautiful on account of one single cause, i.e. the participation in the form of beauty. I also suggest that this assumption should contribute to our judgement about the real world because it enables our search for the definition of F-ness, which is required to judge whether or not something is F in reality, by positing the single form of F-ness.