Thinking about a necessary being › What the description says

Anselm describes God through an unsurpassability condition: no greater being can be conceived. Greater concerns excellence, rather than physical size. The description is intended to rule out a superior that thought could place above its subject. It is not simply a claim that God happens to outrank the beings currently known to us.

There is a difference between the greatest member of a familiar group and a being that cannot be surpassed in thought. The fastest runner in a particular race can still be slower than a conceivable runner. A winner selected from an existing group therefore need not meet Anselm's condition. This hypothetical comparison illustrates the scope of his description; it does not prove that the description is coherent or instantiated.

Nor should the condition be treated as a complete mental picture of God. Saying what would rule out a supposed candidate differs from comprehending every feature of its subject. Chapter XV makes the difficulty explicit by saying that God exceeds what can be conceived. The book therefore combines a condition governing thought about God with an acknowledgment of the limits of that thought.

That combination creates a question for the reader: how much understanding of a description is enough to support the argument? We can understand a rule without surveying everything it concerns. Yet merely pronouncing a sequence of words does not guarantee that those words describe a possible being. This gap is one of the points the debate needs to examine.