 Several medieval texts describe a form of debate called obligationes. There were two disputants, Opponens and Respondens. At the beginning of a session, the disputants would agree on a ‘positum’, typically a false statement. The job of Respondens was to give rational answers to questions from Opponens, assuming the truth of the positum; above all he had to avoid contradicting himself unnecessarily. The job of Opponens was to try to force Respondens into contradictions. So we broadly know the answer to the Dawkins question, but we don’t know the game rules! The medieval textbooks do describe several rules that the disputants should follow. But these rules are not stipulated rules of the game; they are guidelines which the textbooks derive from principles of sound reasoning with the aid of examples. (Paul of Venice justifies one rule by the practice of ‘great logicians, philosophers, geometers and theologians’.) In particular it was open to a teacher of obligationes to discover new rules. This open-endedness implies that obligationes are not logical games in our sense.