I will offer a defence of Anselm's Ontological Argument, building on some suggestions made by Prior. The defence offered avoids one of the objections commonly levelled against the Ontological Argument. I will not consider whether the use of this objection involves a misinterpretation of the argument as put forward by Anselm. It might, for example, be held that the argument of Proslogion 2 is programmatic, and points forward to Prosiogion 3, and arguments given by Anselm in his Reply to Gaunilo. (...) In particular it might be denied that Anselm holds that what is greater about what exists in reality is just that it exists in reality. While what I have to say will start from points made by Prior, I do not intend to suggest that Prior holds that there is a defence possible for Anselm's argument such as I will offer. What I have to say involves emphasizing modal notions, and treating Anselm's argument as a modal argument. Thus it comes down to defending Anselm's argument in Proslogion 3 in preference to the Proslogion 2 argument. (shrink)