Avicenna's reworking of Porphyry's 'common accident' in the light of Aristotle's Categories

The present paper deals with Avicenna’s critical analysis of the third definition of ‘common accident’ that Porphyry provides in the Isagoge. The starting point for the present inquiry is chapter I.14 of Avicenna’ reworking of Porphyry’s Isagoge (Kitab al-Madhal) in the Book of the Cure (of which an English translation is provided in Appendix A). Firstly, Avicenna’s refutation of Porphyry’s definition of common accident (Porph., Isag., 13.4-5 Busse) is examined in section I. Secondly, in section II the core doctrinal issue at stake in Avicenna’s refutation of that definition is presented, namely his distinction between the ontological accident (i.e. the accident) and the logical accident (i.e. the accidental). By way of conclusion, it will be argued that Avicenna’s reworking of the notion of ‘accident’ reveals, at the same time, awareness of the preceding and contemporary exegetical tradition, and a conscious detachment from it on the basis of an independent interpretation of Aristotle’s Categories.