Abstract

Descartes famously rejected final causes with form and matter as general principles of
explanation in philosophy of nature. He introduced a radical dualist ontology to ground
his new mechanistic philosophy of nature without threatening traditional views of
mind and morality. Among these was the doctrine of human being as a unity of mind
and matter that captures important aspects of our experience, and was granted by
Descartes in some form all along. In confronting objections to his dualism he fell back
on hylomorphic language, arguing that mind and body although complete substances
in themselves are incomplete with respect to the human being they compose through
a real or substantial union, describing the mind (the rational soul) as a substantial form
and as informing the body.

This chapter examines Descartes’s use of and entitlement to hylomorphic
language, and reflects on the tensions that his view of human nature creates for his
dualism. Recent discussions of Descartes’s relation to hylomorphism have sensibly
focused on its late medieval Scholastic versions. Both the concepts of soul or mind and
those of matter had changed enough over centuries of discussions to adjust
hylomorphism to Christian doctrine, and the concept of matter to scientific discoveries
and practice, so that the step from the doctrines discussed by the later Scholastics to
Descartes’s would seem less of a leap and more of a continuum than earlier thought. I
will not trace that development here but examine some crucial texts in the light of recent interpretations which take Descartes’s holistic view of the mind-body union seriously while at the same time trying to save his dualist commitments.