普遍化可能性と実践の論理

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抄録

　It could be said that universalizability is an accepted and plausible thesis for moral discourse. It claims that value-judgments are valid only if they are universalizable. One would not fail to notice that it was R. M. Hare who, in line with Kant, built a unique theory upon the idea of universalizability. Hare presented this thesis not as a substantial claim in normative ethics, but as one based on ‘logic,’ which is counted as an innovation in the history of ethics. 　Nevertheless, Hare’s argument for this thesis is said to contain a difficulty. According to traditional interpretations, Hare’s second major work Freedom and Reason（FR）left a logical leap. Hare in FR, they say, claims value-judgments are universalizable because value-words have descriptive meaning. However, the trivial fact of descriptive meaning does not logically entail such normative requirements which the universalizability thesis implies. 　This paper will argue that these traditional interpretations overlook the continuity in Hare’s ethics, namely between his first major work Language of Morals（ LM）and FR. The argument for normative requirements of value-judgments in FR presupposes the argument for universalizability in LM. In LM, Hare did argue value-judgments are felicitous only if done in a universalizable manner, for making value-judgments is a form of speech act, i. e. ‘decision of principle.’ Given this, one will easily understand why universalizability as felicity necessarily involve the normative requirements of value-judgements. Put in another way, one will not be able to understand the argument in FR without understanding the one in LM. 　Hare submitted the universalizability thesis as a ‘logical’ thesis, and the word ‘logic’ here has a wider connotation, which includes internal rules of practice in which we all are engaged. And this indicates Hare’s philosophical insight that why and how we should universalize our value-judgements can only be grasped from the point of view which we have as participants of normative practice.