著者

深山 洋平

出版者

北海道大学哲学会

雑誌

哲学 (ISSN:02872560)

巻号頁・発行日

vol.52, pp.55-69, 2018-12-02

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The first aim of this paper is to explicate the intention of a picture which was found on the introduction Web page of emeritus Koji Nakatogawa at Hokkaido University and which visualizes inference from seeing smoke at some place to the existence of fire there. It turns out that the picture is influenced from a book whose authors include mathematician F. W. Lawvere and that the intention is clarified by using Lawvere's elementary topos theory. The second aim is to point out a conflict between Nakatogawa's view that "static" set theory is opposed to "dynamic" category theory and Lawvere's conception of the topos of abstract sets and that of variable sets.