著者

瀬口 昌久

出版者

日本西洋古典学会

雑誌

西洋古典学研究 (ISSN:04479114)

巻号頁・発行日

vol.42, pp.25-35, 1994

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An Eleatic stranger presents the definition that being is nothing but power or function(dynamis)in the Sophist(247d-e). However, this definition is not accepted by the friends of the Forms because they are afraid of the paradox that Reality must be acted upon in so far as it is known(248a4-248e5). They believe that cannot happen to the changeless. I shall attempt to clarify the purpose of this paradox and whether the definition of being as power is maintained. D. Keyt analysed the paradox and found that it is based on five premises (Plato's Paradox that the Immutable is Unknowable, PQ, 19, 1969, 1-14). (1) Real being is completely changeless. (2) Being is known. (3)To know is to act on something. (4)If knowing is acting on something, then that which is known is acted upon. (5)To be acted upon is to be changed. Premises(2)-(5)entail the denial of(1) , which contradicts the belief of the friends of the Forms. Does Plato avoid the contradiction? If so, how? As Keyt points out, no one has claimed that Plato rejects either(2) or(4). I shall consider premises(1) , (3) and(5). Many commentators(e. g. J. Moravcsik, G. E. L. Owen, I. M. Crombie, R. S. Bluck, W. G. Runciman)think that Plato rejects(1). However, they are claiming that the Forms are subject to change only in the sense that dated propositions are true of them, not that the Forms undergo a change of their own nature when they are known. If the Form of Justice is known by an individual, a temporal proposition is added to the Form, and then the Form is changed in an accidental way. However, this view has no textual evidence. On the contrary, it contradicts the statement in the Timaeus that the Forms are timeless (37e1-38a8). W. D. Ross suggests that(3) is the only explicit hypothesis of the five and holds the view that in knowledge the object acts on the mind not vice versa. Ross ignores the fact that the paradox is meant to damage the claim that the power of acting or being acted upon belongs to becoming but not to being (Keyt, p. 4). Other commentators(F. M. Corn ford, H. Cherniss, G. Vlastos)suppose that Plato himself will abandon(5). They think that the spiritual motion distinguished from the physical does not alter its objects. Keyt and A. C. Ray criticize this interpretation on the ground that the distinction between physical and spiritual motion is not drawn in the Sophist. If it had been drawn, the friends of the Forms would not have adhered to(5). I support the denial of(5). The problem is why the friends of Forms stick to(5). I connect the definition of being as power with the perception theory in the Theaetetus(155e-157d). "More refined and subtle people" in the Theaetetus maintain the principle that everything arises from the motion of two kinds of power, the one being active and the other passive. I suggest the definition of being in the Sophist derives from this Heraclitean principle of being. Plato deliberately omits the crucial word "kinesis" in the Heraclitean principle from the definition of being in the Sophist. It is by virtue of this omission that the definition of being can be applied to real being as well as material things. Moreover, when the notion of the active and passive power is distinguished from that of changes or motions, the definition will ensure Plato's view of the communion of Forms. The paradox shows the absurdity which arises when we connect the active and passive power of Forms with motion or change. Plato's aim in the paradox is to establish the view that the power of Forms need not cause changes in its objects. I conclude that the definition of being as power is maintained and not given up after the paradox and is the key to understanding the meaning of real being.