Abstract

One of the most salient and far-reaching differences between modern “philosophy of mind” and medieval “philosophical psychology” has to do with the relation between soul and mind. For Descartes and the vast majority of his early modern successors, there is no meaningful distinction between these two notions. “Soul” (anima) and “mind” (mens) are just two names by which we refer to one and the same “thinking thing” (res cogitans). The problem that was created by Descartes, and that has occupied philosophy of mind until today, is how to explain the relationship between this thinking thing, the immaterial and unextended mind, and the body, defined in terms of matter and extension (res extensa). In its modern, Cartesian form, the “mind-body problem” was unknown to medieval thinkers. For them, the notion of “soul” had a much broader meaning than that of “mind.” The soul is not merely a thinking thing, but the principle that accounts for the whole range of functions associated with life: nutrition, growth, reproduction, locomotion, sensation, imagination, memory, and thinking. Hence, soul is not specifically human: plants and non-human animals have souls as well, albeit less complex and less powerful ones. From the perspective of medieval philosophical psychology, the primary problem is not how to explain the relationship between mind and body, but rather how to explain the relationship between soul, as the “principle of life” in general, and mind (or intellect), as the “principle of thinking.” ¹