Gaunilo of Marmoutiers

Background

Gaunilo (fl. c. 1078) was a Benedictine monk of Marmoutier, near Tours, known to history through a single short work: In Behalf of the Fool, the first and most durable objection to Anselm of Canterbury's ontological argument, written within months of the Proslogium itself. Almost nothing else about his life is securely known. Anselm thought the critique important enough to answer point by point and directed that Gaunilo's objection and his own Apologetic be copied together with the Proslogium — which is why our corpus preserves all three in one volume.

Gaunilo answers on behalf of the fool of Ps 14:1 (bib) — the unbeliever Anselm claimed his argument could convince — while himself remaining a believer. His stance in the debate is therefore worth stating precisely: he attacks the proof, not the God. The frontmatter stance above tracks the view's dialectical role (against the argument), not Gaunilo's own theology.

Positions held in this wiki

• The Ontological Argument — originator of the parody strategy, still judged the sharpest instrument against Proslogion-II-style arguments. His lost island — "somewhere in the ocean is an island, which, because of the difficulty, or rather the impossibility, of discovering what does not exist, is called the lost island," richer "than is told of the Islands of the Blest" — is deployed against anyone reasoning that because the island is understood it must exist: "either I should believe that he was jesting, or I know not which I ought to regard as the greater fool" (Gaunilo, In Behalf of the Fool §6). He also anticipated two modern objections: that "it should be proved first that this being itself really exists somewhere" before its supremacy is inferred (§§5–6), and that inconceivability-of-non-existence cannot do the work Anselm needs.

Key works in our corpus

• In Behalf of the Fool (c. 1078, Deane trans. 1903) — in corpus, bound as an appendix with the Proslogium and Anselm's Apologetic. The full exchange can be read in sequence in a single file — a rare case where our corpus holds both sides of a medieval debate verbatim.

Principal critics

• Anselm of Canterbury — the Apologetic: the original argument concerns a unique formula, "that than which a greater cannot be conceived," to which island-reasoning cannot be adapted (Anselm, Apologetic chs. II–III).
• Alvin Plantinga — the modern intrinsic-maximum reply: island-greatness has no maximum, maximal greatness does; the parody's premises are therefore not "no less acceptable" than Anselm's.

See also

• David Hume and Immanuel Kant — the later, independent strands of the critical tradition Gaunilo began.
• Graham Oppy — the contemporary generalization of the parody strategy.
• Thomas Aquinas — a second insider critic of the a priori proof, on different grounds.