William Vincent

The doctrine of divine simplicity says that God is not composed of parts (physical or metaphysical). Modal collapse arguments aim to show that the necessary co-existence of God and creation follows from the doctrine. As noted by Christopher Tomaszewski, R. T. Mullins’s version of this argument assumes that a crucial term occurring within its premises is rigid, leaving the argument invalid or question begging. I examine a recent attempt by Mullins to repair his argument and defend the rigidity of this term. Mullins assumes a test for discerning rigidity on which he and Tomaszewski agree. I argue that this test is false and then provide a new test. My test bodes ill for modal collapse arguments in general.

Kit Fine’s logic of essence and his reduction of modality crucially rely on a principle called the ‘monotonicity of essence’. This principle says that for all pluralities, xx and yy, if some xx belong to some yy, then if it is essential to xx that p, it is also essential to yy that p. I argue that on the constitutive notion of essence, this principle is false. In particular, I show that this principle is false because it says that some propositions are essential to yy even though those propositions are only about some of its members. I then consider modifications to the principle appealing to consequential essence and argue that such a modification is inconsistent with a central desideratum of Fine’s approach to metaphysics, what I call his neutrality condition.

An essential property of a thing tells us about the real definition of that thing. In this dissertation, I argue that a real definition states conditions on the identity of things and explains how they differ from other individuals or members of other kinds. I then apply this account to show that some essential properties are discovered by science. I also argue contrary to reductionist accounts of essence and show that several of Kit Fine's applications of the notion of essence to ontological dependence and to the reduction of modality, are spurious. Finally, I argue that the real definition of each human person accounts for their personal identity over time.