Anselm's Temporal‐Ontological Proof

In his Reply to Gaunilo , Anselm presented two additional arguments for the existence of God beyond those that appear in the Proslogion . In “The Logical Structure of Anselm's Argument,” Robert M. Adams isolates each. One, he develops into a modal ontological argument along the lines of other 20th century ontological arguments (e.g., those of Malcolm, Hartshorne, and Plantinga). The other he sets aside with the following remark: “[this argument] turns on the philosophy of time, not the philosophy of logic.” Now the argument's time has come. In this paper, I show the following: (i) this argument is valid in system K, and so requires fewer logical resources than other modal ontological arguments; (ii) its axiological premise is plausible, requiring only the judgment that a perfect being cannot begin to exist, and can be defended; (iii) its metaphysical premise follows from David Lewis's recombination approach to modal plenitude; (iv) unlike other modal ontological arguments, it requires as a premise only that a perfect being is possible, not that one is necessarily possible; and (v) while it avoids parodies and the charge of begging the question, it does face a symmetry counterargument, although one that is more complicated than standard symmetry objections.