Version: v1, Published online: 1998
Retrieved January 19, 2019, from https://www.rep.routledge.com/articles/biographical/descartes-rene-1596-1650/v-1
12. Life and the foundations of biology
The last part of the Cartesian programme was his biology. First presented in the Treatise on Man, part of The World project which was abandoned in 1633 when Galileo was condemned, Descartes intended to rework some of that material and publish it – as Parts V and VI of the Principles under the title ‘De Homine’. Although he never finished this rewriting, it is clear from the notes left behind that it was very much on his mind in years that preceded his sudden and premature death.
His hope seems to have been to show how, from matter and the laws of motion alone, life would arise spontaneously as matter came to organize itself in an appropriate way (Discourse V). Unfortunately he never worked out this view, suggestive of later theories of evolution, in any detail. Yet, he was quite clear that all the functions of life (with the exception of thought and reason in humans) are to be explained not in terms of the soul, the principle of life, but in terms of matter in motion. Accordingly, in the Treatise on Man, he accounts for a variety of phenomena, including digestion, involuntary motion, the action of the heart, and sense perception, in purely mechanical terms. (Summarized in Discourse Part V, with special emphasis on the circulation of the blood.)
While Descartes’ biology was controversial among his contemporaries, one aspect was especially so. According to his account, there is only one kind of soul in the world, the rational soul, which humans and angels have and animals do not. Humans are organic machines, collections of matter organized so as to be able to perform vital functions, attached to rational souls. Animals, on the other hand, are just machines: their behaviour is purely mechanical and they are, strictly speaking, incapable of conscious experience of any sort (Discourse V).
Garber, Daniel. Life and the foundations of biology. Descartes, René (1596–1650), 1998, doi:10.4324/9780415249126-DA026-1. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/biographical/descartes-rene-1596-1650/v-1/sections/life-and-the-foundations-of-biology.
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