The Necessary Conditions for Perception. A Triadic Relation
The preceding chapters discussed Aquinas’s position on the perceptual objects: the proper or special sensibles, the common sensibles, and the incidental object of sense. In addition, the role of the proper medium as a necessary condition for sensation, especially the role of the transparent in visual sensation, was articulated in the preceding chapter. The next step in this building project is to reconstruct an adequate philosophical analysis suggesting what the complete theory of sensation/perception might look like.
A half-century ago, Ryle raised three issues that are important in considering Aquinas’s theory of intentionality for sensation and perception:
- (a) What is the causal relation between objects in the world and our intentional awareness of these objects?
- (b) Does efficient causality offer a sufficient condition for explaining perception?
- (c) How do human perceivers get beyond sensations alone and become aware of ‘things’?
Recent work in the philosophy of mind considers these issues in some detail. The focus of this chapter is on sensation theory in Aquinas, with special reference to intentionality in the context of recent analytic philosophy of mind. Aquinas addresses all three of Ryle’s queries.
-  Gilbert Ryle, ‘Sensation' in H. D. Lewis (ed.), Contemporary British Philosophy III (London: Allen &Unwin, 1956), 427.