Abstract

By examining and comparing the doctrines of Avicenna and Thomas Aquinas on the problem of individuation, as well as relevant passages in Aristotle's Metaphysics and Physics this dissertation argues that the problem of individuation in Avicenna and Aquinas must be accounted for, by situating it within the cognitive context of medieval Aristotelianism. This means, in particular, that both the formulation of the problem and the solution proposed for it by these authors are determined by their respective appropriation of Aristotelian essentialism. In support of this claim, this study shows that individual essence is the principle of individuation in both authors, not matter as a still persisting interpretation of individuation in these authors holds. The argument is made in five steps corresponding to the five chapters of the dissertation. First, the cognitive context of medieval Aristotelianism is defined, while the relative importance of the local contexts of eleventh-century Islamic East and thirteenth-century Latin West in which Avicenna and Aquinas respectively wrote, is emphasized. The distinction, by Avicenna, of essence from existence, on one hand, and the primarily individual nature of the Aristotelian notion of essence, on the other hand, are then shown to lead to the notion that essences do exist in reality, and that they are the cause, i.e. the principle, of individuation. This thesis and its implications are then verified and qualified in the context of Aristotelian physics and finally the contexts of Avicennian and Thomist theologies are evoqued to examine the problem of God's knowledge of individuals