Nicole Oresme and Modi Rerum

This paper is the written version of my contribution to the International Conference «30 years Logica modernorum» held in Amsterdam in November 1997 in honor of the late prof. Lambertus M. de Rijk. Research on Oresme’s modi rerum theory was in the first stage, while now we can read the critical edition of Oresme’s Physics commentary, where modi are introduced and widely used. In this paper I shall consider Oresme’s polemical use of modi rerum, trying to set it in the larger context of both his ontology and his epistemology. Oresme’s challenge to either a realist or terminist ontology by means of modi rerum conceals probably an attack to William of Ockham; Oresme refers explicitly to Ockham concerning exclusive propositions, but I think that on many other occasions the polemical target of Oresme’s criticism can be reasonably identified in William of Ockham or in some unnamed followers of the Venerabilis Inceptor. Some hints are reserved also to the possible sources of Oresme’s modi rerum.