For 10 points, name this argument for the existence of God developed by St. Anselm.
One objection to this idea argues that its logic leads to the existence of a "Lost Island." A modal version of this idea argues that its conclusion cannot be proven, but that it is rational to accept its conclusion. According to Kant, this idea falsely assumes that existence is a predicate. Gaunilo rejected this idea, whose modal version was formulated by Alvin Plantinga. Descartes' Fifth Meditation puts forth a version of it based on the principle that necessary existence is one of the perfections of a conceivable all-perfect being. This argument is commonly phrased as "a being than which nothing greater can be conceived" must exist. For 10 points, name this argument for the existence of God developed by St. Anselm.
One objection to this idea argues that its logic leads to the existence of a "Lost Island.
the {ontological} argument [or clear knowledge equivalents]