Abstract

There are surprisingly few texts in which Avicenna discusses our knowledge of separate substances. The most extensive account occurs in Metaphysics 3.8, a text which was cited by Aquinas in a small number of works from relatively early in his academic career. Aquinas’s attitude to Avicenna’s account, which he dubbed knowledge per impressionem, is by no means uniform, even within a single work. Sometimes Avicenna is an adversary; sometimes he is an ally; still other times he is an innocent bystander. I explore the reasons for Aquinas’s shifting evaluation of Avicenna’s theory and show that Aquinas’s attitude depends in part upon whether the separate substance in question is God or the angels, and whether he is considering the soul as separated or embodied. Ultimately I argue that Aquinas’s abandonment of knowledge per impressionem reflects his general move away from any Avicennian influences that smack of dualism in his eyes