JOHN DUNS SCOTUS AND THE ONTOLOGY OF MIXTURE Lucian Petrescu Abstract: This paper presents Duns Scotus's theory of mixture in the context of medieval discussions over Aristotle's theory of mixed bodies. It revisits the accounts of mixture given by Avicenna, Averroes, and Thomas Aquinas, before presenting Scotus's account as a reaction to Averroes. It argues that Duns Scotus rejected the Aristotelian theory of mixture altogether and that his account went contrary to the entire Latin tradition. Scotus denies that mixts arise out of the four classical elements and he maintains that both the elemental forms and the elemental qualities are lost in the mixture. Consequently, he denies the distinction between the process of mixture and that of substantial change through generation and corruption. The reassessment of Scotus's accountdevelopment of this discussion and argue that his account was more original than previously thought. Maier noted the importance of Duns Sctous's account for the subsequent views of authors such as William of Ockham or Gregory of Rimini, but she still treated him as developing a Thomist view on mixts. She speaks of a "clarification" of the Thomist theory (107) and of a "Thomist-Scotist view" (111). To appreciate Scotus's novelty, a revision of the main solutions provided within Latin Aristotelianism is needed. I will thus revisit four main authors: Avicenna, Averroes, Thomas Aquinas, and Duns Scotus. In the first section, I set the stage by summarizing the problem posed by Aristotle's conception of mixts. In the second section, I present the key positions inherited by the Latins from