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The Frege–Church ontology is an ontology, a theory of existence. Everything is considered as being in three categories, object (referent, denotation), name, or concept (sense). The ontology was developed by Alonzo Church〔Church, Alonzo. "A Formulation of the Logic of Sense and Denotation." In Structure, Method and Meaning: Essays in Honor of Henry M. Sheffer, edited by P. Henle, H. Kallen and S. Langer, 3- 24. New York: Liberal Arts Press, 1951.〕 based on ideas of Gottlob Frege〔Gottlob Frege. "Über Sinn und Bedeutung" in ''Zeitschrift für Philosophie und philosophische Kritik 100'': 25-50. Translation: "On Sense and Reference" in Geach and Black (1980).〕〔 Gottlob Frege. "Über Begriff und Gegenstand" in ''Vierteljahresschrift für wissenschaftliche Philosophie 16'': 192-205. Translation: "Concept and Object" in Geach and Black (1980).〕 to resolve some paradoxes. The ontology is related to certain modal logics. ==Paradox of the name relationship== *Suppose we are in the year 1995. Suppose Mary believes that Pluto (at the time still considered a planet) is the farthest planet from the sun. Because of Pluto’s irregular orbit, the orbit of Pluto crossed the orbit of Neptune, so that in 1995, the farthest planet from the sun is Neptune. Suppose Mary does not know this fact. : If ''x''=''y'' and ''y''=''z'', then substituting ''z'' for ''y'', ''x''=''z''. : (1) Mary believes that Pluto = the farthest planet from the sun. : (2) Neptune = the farthest planet from the sun. : Therefore, substituting ‘Neptune’ for ‘the farthest planet from the sun’ in (1), we get : (3) Mary believes that Pluto = Neptune. However, Mary does not believe that Pluto is Neptune, a paradox. The Frege–Church ontology resolves this by saying the belief introduces an "intensional context" whereby the terms following the words "believes that" are in a context whereby they refer not to the denotation of the words, but to the concept associated with the words for the believer. Each word has a name, a denotation, and a concept associated with it. 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「Frege–Church ontology」の詳細全文を読む スポンサード リンク
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