Sense Perception, Theories of

Abstract

Medieval views of sense perception took as their starting point the ancient theories, among which Aristotle’s view was the most influential. The Augustinian tradition considered the soul as the active agent in perception, with it not being affected by the sense organs. The Aristotelian tradition, for its part, considered the sense as a passive faculty, brought into actuality by sense data. Several late medieval authors, inspired by Averroes, developed the notion of an agent sense, an external nonmaterial agent needed for the actualization of the act of perception in addition to forms in the sense organs. The Aristotelian view was mediated to Latin philosophy largely through Avicenna’s faculty psychology. As an explanation of the causal influence of the perceived object on the sensory faculty, a theory of the multiplication of forms was widely accepted. The forms were considered as similitudes of the perceptibilities of the objects, and their function was to make the perception of a particular perceptibility actual. There was wide discussion on the metaphysical nature of these forms. Some authors adopted the view that the causal influence is to be explained merely by action at a distance. The medieval philosophers commonly described the physiological processes involved in perception with help from the medical and optical traditions. The main sensory faculty was seen as located either in the brain or in the heart. The medieval view on perception was committed to the idea of perceptual realism. Awareness of illusions and misperceptions did not lead to skepticism about the possibility of sense perception rendering veridical knowledge, but instead to some reflections on the notion of objective being distinguished from real being. The philosophers also presented diverse views of the conceptuality of sense perception.