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Hume's fork is an explanation, developed by later philosophers, of David Hume's aggressive, 1730s division of "relations of ideas" from "matters of fact and real existence".〔Antony G Flew, ''A Dictionary of Philosophy'', rev 2nd edn (New York: St Martin's Press, 1984), (p 156 ).〕 On the ''necessary'' versus ''contingent'' (concerning reality), the ''a priori'' versus ''a posteriori'' (concerning knowledge), and the ''analytic'' versus ''synthetic'' (concerning language), truths relating ideas (abstract) all align on one side (necessary, ''a priori'', analytic), whereas truths on actualities (concrete) always align on the other side (contingent, ''a posteriori'', synthetic).〔 The necessary is a state true in all possible worlds—usually by mere logical validity—whereas the contingent hinges on the way the particular world is. The ''a priori'' is knowable before or without, whereas the ''a posteriori'' is knowable only after or through, experience in the area of interest. The analytic is a statement true by virtue of its terms' meanings, and therefore a tautology—necessarily true by logic but uninformative on the world's state—whereas the synthetic is true by its terms' meanings in relation to a state of facts, contingent. ==History== Hume's strong empiricism, as through Hume's fork as well as Hume's problem of induction, was taken as a threat to Newton's theory of motion. Immanuel Kant responded with rationalism in his 1781 ''Critique of Pure Reason'', where Kant attributed to the mind a causal role in sensory experience by the mind's aligning the environmental input by arranging those sense data into the experience of space and time. Kant thus reasoned existence of the synthetic ''a priori''—combining meanings of terms with states of facts, yet known true without experience of the particular instance—crossing the tongs of Hume's fork and thus saving Newton's law of universal gravitation. In 1919, Newton's theory fell to Einstein's general theory of relativity. In the late 1920s, the logical positivists rejected Kant's synthetic ''a priori'' and asserted Hume's fork, so called, while hinging it at language—the analytic/synthetic division—while presuming that by holding to analyticity, they could develop a logical syntax entailing, as a consequence of Hume's fork, both necessity and aprioricity, thus restricting science to claims verifiable as either false or true. In the early 1950s, Willard Van Orman Quine undermined the analytic/synthetic division by explicating ontological relativity, as every term in any statement has its meaning contingent on a vast network of knowledge and belief, the speaker's conception of the entire world. By the early 1970s, Saul Kripke established the necessary ''a posteriori'', since if the Morning Star and the Evening Star are the same star, they are the same star by necessity, but this is known true by a human only through relevant experience. Hume's fork remains basic in Anglo-American philosophy. Many deceptions and confusions are foisted by surreptitious or unwitting conversion of a synthetic claim to an analytic claim, rendered true by necessity but merely a tautology, for instance the ''No true Scotsman'' move. Simply put, Hume's fork has limitations. Related concerns are Hume's distinction of demonstrative versus probable reasoning,〔Nicholas Bunnin & Jiyuan Yu. "Hume's Fork". ''Blackwell's Dictionary of Western Philosophy''. Blackwell, 2004.〕〔Garrett Thomson, ''Bacon to Kant: An Introduction to Modern Philosophy'', 2nd Edition, p 218.〕 Hume's law as the fact/value distinction of ''is'' versus ''ought'',〔Nicholas Bunnin and Jiyuan Yu. "Hume's Fork". ''Blackwell's Dictionary of Western Philosophy''. Blackwell, 2004.〕 and Hume's "dilemma of determinism" that our actions are either causally determined or random.〔Blackburn, Simon. "Hume's Fork". ''Oxford Dictionary of Philosophy''. OUP 1996. ISBN 0-19-283134-8. Note: Blackburn does not mention other possible referents of ''Hume's Fork''.〕 Hume makes other, important two-category distinctions, such as beliefs versus desires and as impressions versus ideas.〔''Enquiry Concerning Human Understanding'', Section II.)〕 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「Hume's fork」の詳細全文を読む スポンサード リンク
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