ABSTRACT
This chapter examines the metaphysical underpinnings of Thomas Aquinas's moral theory. The argument articulated is that Aquinas's moral theory is a second order inquiry based squarely on the metaphysical foundations of his theory of the human person, which in turn is rooted in his natural kind ontology. The chapter highlights that a metaphysical inquiry into natural kind ontology is a necessary condition for rendering Aquinas's moral theory coherent and, furthermore, is independent conceptually from a direct first order relation to the existence of God. It analyses the put forward a "new look" at some "old questions" in natural law theory. In discussing the role of metaphysics in Aquinas and in natural law theory, several distinctions must be discussed. One way of reestablishing the importance of substantial form in contemporary metaphysical discussions is through an analysis of Everett J. Nelson arguments postulating the necessity of synthetic necessary causal properties.
