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バートランド・ラッセル 私の哲学の発展
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第10章 「ヴィトゲンシュタインの衝撃」 n.10ウィトゲンシュタインの考えはさらなる結果(帰結)をもたらす。即ち、 |
Chapter 10 The Impact of Wittgenstein, n.10Take, for example, the definition of the number 2. We say that a class has two members if it has members x and y and x is not identical with y, and, if z is a member of the class, then z is identical with either x or y. It is very difficult to adapt this definition to Wittgenstein's convention which requires that we should never use an expression of the form ‘x = y' or 'x ≠ y' but that we should use different letters to represent different things and never use two different letters to represent the same thing. Apart from such technical difficulties, it is obvious, for the reason mentioned above, that, if two things have all their properties in common, they cannot be counted as two, since this involves distinguishing them and thereby conferring different properties upon them. There is a further consequence, namely, that we cannot manufacture an intension which shall be common and peculiar to a given set of enumerated objects. Suppose, for example, we have three objects, a, b, c, then the property of being identical with a or identical with b or identical with c is one which is common and peculiar to these three objects. But, in Wittgenstein's system, this method is not available. |