アリストテレスの「第三の人間」論とイデア論批判

抄録

The most important locus classicus of the 'Third Man Argument' (TMA) in Corpus Aristotelicum is found in the Sophistici Elenchi(178b36-179a10). There the TMA, the last example of sophistical refutations depending on the form of expression, is said to presuppose the admission that the common predicate, like 'man', expresses, because of its form, just what is a 'this' (hoper tode ti), that is, the substantial essence of a being (e.g. Callias) , in spite of the very fact that it expresses a quality, a quantity or some one of the other non-substantial attributes. Depending on Alexander's report of the lost work De Ideis and on his comment on Metaphysics 991a2 ff. that the Platonic Form is a 'universal' essentially predicable of individuals, many scholars explain Aristotle's TMA as follows : that which produces the 'third man' is the individualisation of the universal predicate common to the essences of Form and of particulars. This interpretation has nothing to do with the TMA above in the Soph. El. which will then assert that 'the universal predicate common to the essences of Form and of particulars' does produce the 'third man' without the 'individualisation' of that predicate, for any universal expressing an attribute, once admitted that it expresses an essence, will produce something like a third essence. The TMA in the Soph. El. depending on the similar form of expression of things that are not categorially the same, can be elucidated by a passage from the Topics (103b27-39) which distinguishes two kinds of 'what-is-it' expressions, the intercategorial and the categorial. By the former, one can give the species-genus definition to whatever the given being is, e.g. man, white, a foot length, the latter two of which are not substances, while that definition does not express any categorial 'what-is-it' (the substantial essence), but a quality or a quantity or some one of the other attributes. The truth is then as follows. That which the Form and the particulars have in common is not the eidos qua substantial form, but the eidos qua species (Met. 1059a13) whose one logos is predicated both of the Form and of the particulars as synonymous entities, so that it is limited to setting forth differentiae -a sort of 'quality' {Met. 1020a34)- to the question "what is the species 'man'?", differentiae specific and generic ('biped', 'sensitive' and so on) which are valid to all individual members belonging to the species 'man', but not valid to a substance like Callias himself, endowed with the essence identical with himself. That which causes the TMA is, therefore, to assimilate the inter-categorial 'what-is-it' expression which is in fact an attributive expression, to the categorial 'what-is-it' expression which is, according to Aristotle, the only substantial expression. Aristotle's criticism of the theory of Forms, therefore, does not consist in the following: in spite of the fact that every universal expresses an attribute, the theory of Forms which makes it express the individual, should recognize not only the second being, but the third being both having the same essence as the sublunary beings, but in the following: because of the fact that every universal expresses an attribute, the theory of Forms making it express the essence should recognize not only the second, but the third being both having the same attribute as the sublunary beings. By the first formula of criticism one could be inclined to think that Aristotle purports to emphasize the idealistic character in the theory of Forms, while in the second to see Aristotle's tactics to make the Forms 'universalized attributes'-accidental phenomena-separated from the sublunary substances, which inverts the very relation of Paradeigmata of that world and eidola of this world.