Between Imagination and Gambling. The Forms of Validity in Scholastic Logic. Issue 4 (1st October 2020)

• Record Type: Journal Article
• Authors: Hanke, Miroslav
• Is Part Of: History and philosophy of logic. Volume 41:Issue 4(2020)
• Page Start: 331
• Page End: 351
• Publication Date: 2020-10-01
• Subjects: Logic -- Periodicals; 160.905
• DOI: 10.1080/01445340.2020.1800243
• Languages: English
• ISSNs: 0144-5340

Abstract

Abstract : Scholastic logic provided us with a variety of accounts of validity. With some degree of simplification, validity translated into truth-preservation evaluated against a set of worlds ( casus ) and was tested against a set of counter-models ( instantia ). Which inferences are valid depends on replacing 'a set' by 'the set' in such definitions, in other words by specifying the underlying concept of modality. Four levels of modality can be identified in scholastic logic: what can be imagined ( casus imaginabilis ), what can be the case ( casus possibilis ), what is the case in situations similar to the actual world ( ut nunc ), and what is mostly the case ( ut in pluribus ). The result of these analyses are general accounts of both deductive and inductive validity. The paper aims at various uses of ' casus ' (or equivalent concepts) pertaining to the analysis of validity between the fourteenth-century Calculatores and the eighteenth-century post-Bernoullian or post-Wolffian use of ' casus ' (in the sense of an outcome in the mathematical treatment of probability and probabilistic logic). The way such concepts were appearing or disappearing in scholastic texts written between late medieval and early modern period will be outlined.