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Abstract
In the history of metaphysics, many philosophers have formulated theories about the natures of, and the relationship between, substances (e.g., humans, animals, and plants) and their attributes (e.g., their colors, shapes, and weights). In contemporary metaphysics, one prominent position on the relationship between substances and their attributes is called “Constituent Ontology.” According to Constituent ontologists, the attributes of a substance are intrinsic to the substance, so that the substance can be thought of as a “whole” in relation to its attributes as “parts” or “constituents.” Once, however, we view a substance as a whole composed of different constituents, what is the basis of unity for substances? Call this the “Unity Problem.” This dissertation raises the Unity Problem for Constituent Ontologies in contemporary metaphysics. As I show, Constituent ontologists in contemporary metaphysics—specifically, “Bundle” and “Bare Particular” theorists—do not have an adequate solution to the Unity Problem. To solve the Unity Problem, I turn to the thought of Thomas Aquinas and develop his account of the different act-potency relations which explain the unity of substances. After articulating Aquinas’s account of the different act-potency relations, I critique the most philosophically viable Constituent Ontologies in contemporary metaphysics—namely, Peter Simons’ “Nuclear Theory” and J. P. Moreland’s version of “Bare Particular Theory”—showing their inability to incorporate the act-potency relations and, consequently, their inability to solve the Unity Problem. I show that some common presuppositions shared by Constituent ontologists in contemporary metaphysics must be abandoned to maintain a tenable Constituent Ontology which endorses Aquinas’s solution to the Unity Problem.
