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Extract

There are at issue here, I believe, two related questions: What is an adventitious idea for Descartes, and what is the relation between the understanding and the senses? Miles asserts that there is an adventitious idea of body but that it consists only of the proper sensibles, i.e., colours, sounds, tastes, odours, etc. Only these are given through the senses. Extension is not included in the adventitious idea, but is given only to the understanding. I take this to mean also that the modes of extension, figure, motion and magnitude, are not given through the senses either, since the thought of them presupposes extension. Against this I would say, however, that there are passages in which Descartes seems definitely to be including extension and its modes in what is given through the senses. In Meditation III when he introduces the notion of the adventitious idea it is as one which seems to be produced by external bodies. In his ideas of corporeal things he finds a few which he clearly perceives: extension, figure, relative position and change of positions. His ideas of the other qualities are confused and obscure. In MeditationVI he undertakes to examine the nature of sense, and to enquire whether from those ideas which are apprehended by this mode of thought— “or the mode which I entitle sensing (sensum)” —he could derive any certain proof of the existence of corporeal things. First he perceives by the senses that he has a body. “And outside myself, in addition to the extension, figure and motion of bodies, I sensed (sentiebam) in them” (AT VII, 74f.) hardness, heat, lights and colours, scents and sounds. At the end of the Principles of Philosophy in treating of the senses Descartes says that nothing in external things can be apprehended by us through sense except their figure, size and motion (IV. 198, AT VIII-1, 321). And later he remarks that we observe size, figures and motions by several senses, e.g., by touch, sight and hearing; “we also distinctly imagine and understand this. This cannot be said of other things that come under our senses, such as colours, sound and the like, which are perceived not by several senses but by single ones; for their images are always confused in our minds, nor do we know what they are” (IV. 200, AT VIII-1, 323).