Substance, Accidents and Definition in Giles of Rome’s Quaestiones metaphisicales

Scholars paid scant attention to Giles of Rome’s Quaestiones methaphisicales. This is due to many reasons. The Quaestiones are likely the first of the Aristotelian commentaries written by Giles and all XVI-century printed editions conserve but a reportatio of the course on Metaphysics that Giles probably gave in Paris between 1268/1269 and 1271. Since Giles never edited the text of his lectures, we cannot be sure that Giles approved the list and the contents of the questions we may read today. Moreover, the current list is also incomplete because a study of cross-references in Giles’ Aristotelian commentaries (Donati 1990) showed that Giles wrote other questions, not included in the list we have today. Despite of these features, Giles’ Quaestiones are import both historically and philosophically. They contribute to fixing the chronology of Giles’ first works and to illustrating the metaphysics of the early Giles. In particular, a close examination of the questions on Books VII and VIII of Aristotle’s Metaphysics, devoted to substance and accidents, shows various things. For example, the influence exerted by Averroes’s Commentary on Giles’s teaching and, accordingly, the pivotal role played by the notion of definition in the explanation of the essence of substance and accidents. More generally, such an examination permits us bringing to light the exegetical devices Giles used in order to reconcile Thomas Aquinas’s view of the primacy and unicity of substantial form (a thesis that Giles, albeit with some hesitations, maintains across his career) with his idiomatic position that indeterminate dimensions must precede in some way substantial form. If this were not the case, Giles argues, we could not explain the process of particularization and multiplication of a form that is in itself ‘unparticular’ (imparticularis).