Definizione e dimostrazione nel "Commento Posteriorum" di Giovanni Buridano

This paper offers the first study of part of the doctrinal content of John Buridan’s literal commentary on aristotle’s Posterior Analytics, the Commentum Posteriorum, which, to my knowledge, has hitherto remained unexplored. Since the work is extant in two partially different versions, manuscript witnesses of both versions are consulted. The analysis focuses on a selection of topics from the second book of the Commentum : the relationship between definition and demonstration (with the related problem of assessing in which cases and in which ways a definition may be demonstrable) ; the typically Buridanian fourfold classification of the kinds of definitions employed in a science ; and the quaestio de medio demonstrationis, which was quite traditional at the time. These topics are contextualized within the broader framework of the Latin exegetical tradition of aristotle’s work and compared with two other writings by Buridan on the aristotelian theory of science, namely the Quaestiones in Analytica Posteriora and the Summulae de demonstrationibus. although the Commen - tum certainly documents Buridan’s reliance on Grosseteste’s and aquinas’ commentaries, I will argue that it also displays a good deal of originality. Moreover, the Commentum presents important analogies with Buridan’s Quaestiones and Summulae, although the doctrinal developments in it are less elaborate than in these other more renowned works. Finally, concerning the medium demonstrationis, the Commentum shares the same line of thought of the Quaestiones, being remarkably different from the Summulae.