感覚と思考 : プラトン『テアイテトス』184b4-187a8の構造

<p>In the last argument of the first part in the Theaetetus(184b4-187a8), Socrates tries to refute the first definition of knowledge that it is perception. In the argument he distinguishes between perception and consideration and argues that being(ουσια) belongs to consideration, but not to perception, and therefore that the definition is false, for whatever being does not belong to a being cannot be knowledge. According to the orthodox interpretation, Plato distinguishes between making judgement and having sense experience, and argues that in order to make any judgement one must grasp being, for every judgement has a propositional construction, which requires being as one of its constituents. But in sense experience, for example, in sight we see a colour of an object, but do not see a proposition that an object is coloured in such and such a way. So sense experience does not yield judgement. Hence it is not knowledge. But I cannot accept this interpretation, because it cannot explain why the arguments of the second part restrict kinds of judgement to identity. According to it, the conclusion of the last argument of the first part concludes that perception is not knowledge, but judgement can be knowledge. It follows that any kind of judgement can be a candidate for knowledge. But the argument of the second part deals only with identity judgements. So the orthodox interpretation cannot explain why they restrict kinds of judgement to identity ones. In my view, Plato does not distinguish between making judgement and having sense experience, but between considering basic comprehension in language about our experience and having sense experience. When Theaetetus agress that colour can be percieved through eyes and sound through ears(184c1-185a3), he considers that colour is one thing, sound is another, and that there are 'both things'(αμφοτερω)at once(cf. 185a4-10). Now Socrates analyzes the contents of Theaetetus' consideration in this way: (1) Theaetetus previously considers that there are both(sc. a colour and a sound) (185a8-10). (2) He considers that each of them is distinct from the other and the same as itself(185a11-b1). (3) He considers that both together are two, and each of them is one (185b2-3). (4) He can investigate whether they both are alike each other or unlike (185b4-6). Plato uses the expression 'being(εστον)' in (1), but not in (2)(3)(4) by ellipsis. Plato pays attention to (1). (1) is an assumption for Theaetetus' consideration of 'both things'. So the being(εστον) in (1) means an existential assumption, which is necessary to thinking or saying in language. Theaetetus' consideration of 'both things' is also expressed as the consideration that each is and each is not(cf. 185c5-6, c9). To avoid any jump of logic, the consideration that, for example, colour is colour, and colour is not sound. This is an identifying judgement. So the consideration of 'both things, is composed of four contents((1)〜(4)), namely an existential assumption ((1)), and two comparisons with each other((2), (4)) and calculation of number((3)). We can say, therefore, Plato uses 'being' in two senses, that is, the sense of existence and the sense of identity, in this passage, when we consider the basic comprehension about our experience. But the identifying judgement includes the existential assumption ((1)). Thus, if we don't consider 'both things' as comprehended above, we cannot intend to observe and describe each of them and say that an object is perceived to be in such and such a way. Therefore our experience, for example, perceiving, observing, saying, describing, etc., is based on this sort of comprehension in our mind. Therefore, according to my interpretation, it is reasonable to restrict kind of judgement to identity alone, in the argument of the second part. For it has shown that the last argument</p><p>(View PDF for the rest of the abstract.)</p>