Sophismatically Thinking about consequences from universal to singular propositions. A case study from the sophisma OMNIS HOMO DE NECESSITATE EST ANIMA

International audience ; This paper is dedicated to the problem of consequences from essential universal propositions to subordinated singular propositions within the refutations of the refutation (improbatio) of the OHNEA proposition (Omnis homo de necessitate est animal). By introducing some major topics for the study of medieval logic through the lens of sophismatic literature, it raises methodological issues in the history of logic, especially considerations upon the role played by logical practices. After a brief survey of the way 13th century logics of existence significantly differ from 14th century varieties (§1), we offer a description of the two strategies followed in order to dismiss the improbatio and save the truth of the OHNEA proposition. We suggest that, in an earlier stage of the discussions, the improbatio was only a one-step argument, consisting in A1 (§2). We then offer (§3) a detailed examination of the refutation at step 1 (A1), where the Aristotelian origins of the ut nunc/simpliciter distinction are clarified. A non-syllogistic stage of the “ut nunc/simpliciter rule” is delineated. We offer also a brief study the idea of “ut nunc terms.” The stress is put on the way the notion of a fallacious confusion of simpliciter and ut nunc predications could damage large portions of medieval logic (§3.1). We then observe the various reformulations of the rule as a syllogistic rule (“Ut nunc/simpliciter syllogistic rule”), pointing at the ambiguities of the positions defended, as well as on the unsolved issues, such as the famous problem of the two Barbaras. We superficially introduce the solution offered by Robert Kilwardby, that is, the “appropriation rule.” We show how Kilwardby’s solution was recorded in a newly-identified English OHNEA sophisma in the manuscript Gonville and Caius 367/589 (§ 3.2). We eventually turn to the paradoxes involved in the refutation at step 2 (§4). The conclusion explores the metaphysical and semantical foundations of the discussions, namely the notion that ...