The Defence of a Fool (French: Le Plaidoyer d'un fou) is an autobiographical novel by the Swedish writer August Strindberg. The narrative is based on Strindberg's marriage to Siri von Essen. The book was written in French and first published in a German translation in 1893. It has also been published in English as The Confession of a Fool, A Madman's Defence, A Fool's Apology and A Madman's Manifesto.