In this paper, Anselm’s argument for the uniqueness of God or, more precisely, something through which everything that exists has its being is reconstructed. A first reading of the argument leads to a preliminary reconstruens with one major weakness, namely the incompleteness of a central case distinction. In the successful attempt to construct a more tenable reconstruens some additional premises which are deeply rooted in an Anselmian metaphysics are identified. Anselm’s argument seems to depend on premises such as that if (...) two things have the same nature, then there is one common thing from which they have this nature and in virtue of which they exist. Furthermore it appears that infinite regresses are excluded by the premise that if everything that exists is through something, then there is something through which it is “most truly”. (shrink)

This paper reconstructs and discusses a proof of God’s existence by Anselm of Canterbury’s friend Ralph of Battle, developed in his recently edited De nesciente, a fictitious dialogue between a Christian and an atheist. Without precedent in antiquity and the Middle Ages, Ralph’s proof has never been examined in detail. It combines a “cogito” argument with a two-part cosmological argument. The paper first presents the textual basis and an exegetical interpretation of Ralph’s reasoning, classifies the parts of the proof historically (...) and systematically, and then compares these with the proofs of God’s existence as well as other arguments in Anselm’s Proslogion and Monologion. Finally, it points out some similarities between Ralph’s “cogito” argument and a passage in the Liber pro insipiente, which may suggest that this anonymous critique of Anselm’s Proslogion proof was authored not by Gaunilo, as traditionally thought, but by Ralph. (shrink)

Latest version of my SEP entry on ontological arguments, which first appeared in 1996. General discussion of ontological arguments. Includes a brief historical overview, a taxonomy of different kinds of ontological arguments, a brief survey of objections to the different kinds of ontological arguments identified in the taxonomy, and more extended discussions of Anselm's ontological argument (Proslogion 2), Godel's ontological argument, and Plantinga's ontological argument.