Abstract

Descartes' writing on optics were important to the victory of the new mechanistic natural philosophy over the Aristoteleans. His innovations, however, destroyed the bases of Aristotelean realism, and contained the seeds from which Berkeley's perceptual idealism developed. This essay examines the interweaving of philosophical and scientific considerations in Descartes' theory of vision against the background of Aristotle's theory of perception, and traces the way in which his theory of vision developed, through the work of Malebranche and Locke, in an increasingly idealistic direction, culminating with Berkeley's New Theory of Vision. ;The first chapter presents the Aristotelean view and attempts to single out some aspects important to his perceptual realism. The second documents Descartes' break with that tradition, focussing especially on his account of perception in Rule XII. The mechanization of light and color and the significance of this are discussed in Chapter III. ;Chapter IV focusses upon the processes of perception with special attention his account of visual spatial perception and the way in which his physiological hypotheses entangled him in problems about the nature and role of the images involved in vision, and about the judgments by means of which the mind corrects for defects in these images. ;In the last chapter three strands of thought growing out of Descartes' theory of vision are traced through the work of Malebranche and Locke to their culmination in Berkeley's New Theory of Vision, and it is shown how they are woven together there to establish visual idealism. ;In conclusion it is noted that Berkeley's argument would not have been possible in the Aristotelean framework. Aristotle's metaphysical assumptions preclude the theory that ideas are the objects of perception, the distinction between proper and common sensibles does not permit the subjectivization of colors, and the function of the common sense makes impossible a sharp distinction between seeing and judging of the sort Berkeley relies on.