Recent years have seen increased interest in Aquinas’s account of perception, its connection to other aspects of his thought and its relation to other theories, such as Kantian and empiricist ones. The present essay begins by discussing contributions to the understanding of Thomas’s position advanced by David Hamlyn and Anthony Lisska and later engages with Aquinas’s writings directly. It poses the question, ‘What sort of a theory does Aquinas offer?’ and suggests it is akin in type if not in substance to Quine’s ‘naturalised epistemology’. Aquinas holds that all human knowledge derives from experience, but I argue that this does not imply (as it would with a strict empiricism) that it is reducible, directly or indirectly, to the contents of immediate sense experience. This is because of the role of two capacities: the cogitative power and the active intellect in constructing contents that transcend immediate experience but which are expressed in perception. Also, some concepts are non-empirical. This leads to a consideration of the sense in which Aquinas is or is not a metaphysical and epistemological realist.
