"Descartes on Person and Things"

Descartes asserts the union is a substantial union. The union consists in the interaction of mind and body or a substance besides mind and body. Neither of these interpretations makes sense of the texts/terminology of unio substantialis. It would not have implied the unity of the human being was the same as of a substance. The metaphysical theorizing is legitimate despite our epistemological dependence on phenomenological data to establish there is a union and that its nature is sui generis.