Abstract

This dissertation primarily analyzes the metaphysics of the claims about God Aquinas' version of divine simplicity comprises, and seeks the underlying reasons for these claims in some of the groundwork assumptions particular to his own Medieval-Aristotelian ontology and theory of explanation. ;Contemporary analytic philosophers of religion debating the suitability of metaphysical simplicity as an attribute of the Judeo-Christian God frequently cite Thomas Aquinas' classic and influential version of divine simplicity as a paradigm of the position. However, the participants in these discussions too often do not well understand either the metaphysics or the supporting argumentation of Aquinas' version of divine simplicity. ;Aquinas articulates and defends God's metaphysical simplicity in the terms of a Medieval-Aristotelian ontological and semantic framework now generally unfamiliar to the vast majority of his modern readers. In terms intelligible to the twentieth century philosophically educated reader, I reconstruct the original theoretical context from which the claims Aquinas' version of divine simplicity derive their meaning, and hence derive their far-reaching implications for the rest of his philosophical theology. By first examining the various metaphysical distinctions in creatures Aquinas recognizes, I recover for the modern ear both the sense and underlying logic of the claims that God is subsistent being , is pure actuality , is also identical with the divine essence, and is thus lacking all ontological composition. ;Subsequent analysis of his major arguments for these claims about God reveals how divine simplicity in Aquinas is a theological position that is in a way already implicit in a metaphysics of composition driven by the distinctions between essence and existence, and actuality and potentiality. I also show how divine simplicity at bottom follows from a demand that the divine nature be the self-sufficient, unconditioned explanation of all else. I further argue that divine self-sufficiency is itself a product of the particular version of the principle of sufficient reason Aquinas imposes on the phenomena of his universe. ;In the final stage of the work, I shift focus from the metaphysics of divine simplicity to the problems it poses for divine predication. Aquinas' account of divine naming fundamentally involves his application of certain key semantic, metaphysical, and cognitive psychological assumptions to the problem of meaningfully ascribing multiple positive predicates to a simple and per se unknowable divine essence