Descartes understood the subject matter of physics (or natural philosophy) to encompass the whole of nature, including living things. It therefore comprised not only nonvital phenomena, including those we would now denominate as physical, chemical, minerological, magnetic, and atmospheric; it also extended to the world of plants and animals, including the human animal (with the exception of those aspects of the human mind that Descartes assigned to solely to thinking substance: pure intellect and will). Descartes wrote extensively on physiology and (...) on the physiology and psychology of the senses. This chapter examines the notions of *physiology* and *psychology* in medical and natural philosophical works of Descartes' day; follows his efforts to bring physiology into his mechanistic idiom; considers the relation between physiology of the animal machine and psychological functions that yield functionally appropriate behavior; goes into his physiology and psychology of vision; and elaborates the tension in Descartes' works between his metaphysically supported micro-corpuscularism and his discussion of the animal machine as an organic unity comprising various functionally and teleologically characterized systems. The chapter draws on Descartes' works in both metaphysics and natural philosophy, including his Treatise on Man (originally published as L'Homme, 1664). (shrink)

My aim … is to show that the celestial machine is likened not to a kind of divine living being but rather to a clockwork. I consider the human body to be a machine … Although it may exaggerate to say that Descartes fathered the mechanization of biology, it is true that his Treatise of Man provided the first systematic development of the idea that a complete understanding of all the phenomena of life, including all abilities and behaviour of animals, (...) can be achieved by viewing living things as machines. To make this out, Decartes had to learn to think about living things in a new way. My first aim here is to identify the fundamental conceptual innovations at work in Descartes’ attempt to extend the new mechanics to include biology. My second aim is to locate the point at which Descartes’ mechanical imagination runs out. This requires study of Descartes’ scientific work on sense. (shrink)