Gaunilo of Marmoutiers

Who is Gaunilo of Marmoutiers?

Gaunilo of Marmoutiers was an 11th-century Benedictine monk, best known for his criticism of St Anselm's ontological argument for the existence of God. His thesis In Behalf of the Fool takes its name from the fools mentioned in Psalms 14:1 and Psalms 53:1, who say in their hearts that there is no God. Anselm referred to them in developing his ontological argument in the Proslogion.

Gaunilo contends that St. Anselm's ontological argument fails because logic of the same kind would force one to conclude many things exist which it is certain do not. Like an empiricist, Gaunilo thought that the human intellect is able to comprehend only what information it is provided by sensible experience. Little beyond this essay is known of Gaunilo; no other extant writings bear his name.