The Ontological Argument The ontological argument, set forth by Anselm (1033–1109) in the form of a prayer in his Proslogion (1078), contends that the very concept of God in the understanding as “the being than which no greater can be thought” (aliquid quo nihil maius cogitari possit) necessitates his existence because such a concept conceives of the most perfect being that can be imagined as necessarily existing. But, he continues, suppose it exists in the understanding alone: then it can be conceived