Abstract

Aquinas criticizes Averroes’ monopsychism for failing to offer a satisfactory explanation for the obvious fact that “this human being thinks.” However, it also poses great challenges to Aquinas himself to show how an individual person as a material compound can be the subject of thinking, which is supposed to be unmixed with the matter. This essay aims to address these challenges by reconstructing three ontological reasons Aquinas could have offered to demonstrate the compatibility of immateriality and individuality of thinking: the conception of individuality in terms of imparticipability, the complicated status of intelligible species, and the ontological priority of the soul to the body. It argues that the intellective soul as the substantial form of human beings is the ultimate principle of thinking, both for its immateriality and for its individuality.