d on these premises, we obtain the following broad ideas which fundamentally underpin the ontological argument. Firstly, as expressed in Premise 2, we have a coherent idea of a being that The first, expressed by Premise 2, is that we have a coherent idea of a being that instantiates all of the perfections. To say things in a different way, Premise 2 asserts that we possess coherent idea of a being that instantiates every property that makes a being greater, other things being equal, than it would have been without that property. Secondly, Premise 3 asserts that existence is a perfection or great-making property. Accordingly, the very concept of a being that instantiates all the perfections implies that it exists. For example, suppose X is a being that instantiates all the perfections and suppose X doesn’t exist (in reality). Since Premise 3 asserts that existence is a perfection, it follows that X lacks a perfection. But this contradicts the assumption that X is a being that instantiates all the perfections. Thus, according to this reasoning, it follows that X exists. While the syllogism of these premises may itself be compelling, the premises made are fundamentally debatable, or at least requiring clarification, and it is from these premises that problems arise from this formulation.

The first criticism to come about is Gaunilo’s criticism, which is fundamentally worried about the idea that Anselm’s argument moves in an unjustifiable manner from the existence of an idea to the existence of a thing that itself corresponds to the idea. As the objection is sometimes put, Anselm simply defines things into existence — and this simply cannot be done, as it raises the risk that things which simply don’t exist can be treated in the same way. To demonstrate this, Gaunilo formulated the following argument in a similar manner to that of Anselm:

Premise 1: It is a conceptual truth that a piland is an island than which none greater can be imagined (that is, the greatest possible island that can be imagined).