Automata, Living and Non-Living: Descartes' Mechanical Biology and His Criteria for Life

Despite holding to the essential distinction between mind and body, Descartes did not adopt a life-body dualism. Though humans are the only creatures which can reason, as they are the only creatures whose body is in an intimate union with a soul, they are not the only finite beings who are alive. In the present note, I attempt to determine Descartes' criteria for something to be 'living.' Though certain passages associate such a principle with the presence of a properly functioning heart, I show that there are important reasons for also understanding life in terms of a degree of complexity of design.