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''Two Dogmas of Empiricism'' is a paper by analytic philosopher Willard Van Orman Quine published in 1951. According to City University of New York professor of philosophy Peter Godfrey-Smith, this "paper () sometimes regarded as the most important in all of twentieth-century philosophy".〔Peter Godfrey-Smith, ''Theory and Reality'', 2003, University of Chicago, ISBN 0-226-30062-5, pages 30-33 (section 2.4 "Problems and Changes")〕 The paper is an attack on two central aspects of the logical positivists' philosophy. One is the analytic-synthetic distinction between analytic truths and synthetic truths, explained by Quine as truths grounded only in meanings and independent of facts, and truths grounded in facts. The other is reductionism, the theory that each meaningful statement gets its meaning from some logical construction of terms that refers exclusively to immediate experience. "Two Dogmas" is divided into six sections. The first four sections are focused on analyticity, the last two sections on reductionism. There, Quine turns the focus to the logical positivists' theory of meaning. He also presents his own holistic theory of meaning. ==Analyticity and circularity== Most of Quine's argument against analyticity in the first four sections is focused on showing that different explanations of analyticity are circular. The main purpose is to show that no satisfactory explanation of analyticity has been given. Quine begins by making a distinction between two different classes of analytic statements. The first one is called logically true and has the form: :(1) No unmarried man is married A sentence with that form is true independent of the interpretation of "man" and "married", so long as the logical particles "no", "un-" and "is" have their ordinary English meaning. The statements in the second class have the form: :(2) No bachelor is married. A statement with this form can be turned into a statement with form (1) by exchanging synonyms with synonyms, in this case "bachelor" with "unmarried man". It is the second class of statements that lack characterization according to Quine. The notion of the second form of analyticity leans on the notion of synonymy, which Quine believes is in as much need of clarification as analyticity. Most of Quine's following arguments are focused on showing how explanations of synonymy end up being dependent on the notions of analyticity, necessity, or even synonymy itself. How do we reduce sentences from the second class to a sentence of class (1)? Some might propose ''definitions''. "No bachelor is married" can be turned into "No unmarried man is married" because "bachelor" is defined as "unmarried man". But, Quine asks: how do we find out that "bachelor" is defined as "unmarried man"? Clearly, a dictionary would not solve the problem, as a dictionary is a report of already known synonyms, and thus is dependent on the notion of synonymy, which Quine holds as unexplained. A second suggestion Quine considers is an explanation of synonymy in terms of interchangeability. Two linguistic forms are (according to this view) synonymous if they are interchangeable without changing the truth-value. That is, in all contexts without change of truth value. But consider the following example: :(3) "Bachelor" has fewer than ten letters. Obviously "bachelor" and "unmarried man" are not interchangeable in that sentence. To exclude that example and some other obvious counterexamples, such as poetic quality, Quine introduces the notion of cognitive synonymy. But does interchangeability hold as an explanation of cognitive synonymy? Suppose we have a language without like "necessarily". Such a language would be extensional, in the way that two predicates which are true about the same objects are interchangeable again without altering the truth-value. Thus, there is no assurance that two terms that are interchangeable without the truth-value changing are interchangeable because of meaning, and not because of chance. For example, "creature with a heart" and "creature with kidneys" share extension. In a language with the modal adverb "necessarily" the problem is solved, as ''salva veritate'' holds in the following case: :(4) Necessarily all and only bachelors are unmarried men while it does not hold for :(5) Necessarily all and only creatures with a heart are creatures with kidneys. Presuming that 'creature with a heart' and 'creature with kidneys' have the same extension, they will be interchangeable ''salva veritate''. But this interchangeability rests upon both empirical features of the language itself and the degree to which extension is empirically found to be identical for the two concepts, and not upon the sought for principle of cognitive synonymy. It seems that the only way to assert the synonymy is by supposing that the terms 'bachelor' and 'unmarried man' are synonymous and that the sentence "All and only all bachelors are unmarried men" is analytic. But for ''salva veritate'' to hold as a definition of something more than extensional agreement, i.e., cognitive synonymy, we need a notion of necessity and thus of analyticity. So, from the above example, it can be seen that in order for us to distinguish between analytic and synthetic we must appeal to synonymy; at the same time, we should also understand synonymy with interchangeability ''salva veritate''. However, such a condition to understand synonymy is not enough so we not only argue that the terms should be interchangeable, but necessarily so. And to explain this logical necessity we must appeal to analyticity once again. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Two Dogmas of Empiricism」の詳細全文を読む スポンサード リンク
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