 As hinted by its name, the dialogical framework studies dialogues; but it also takes the form of dialogues. In a dialogue, two parties (players) argue on a thesis (a certain statement that is the subject of the whole argument) and follow certain fixed rules in their argument. The player who states the thesis is the proponent, called P, and his rival, the player who challenges the thesis, is the opponent, called O. In challenging the proponent’s thesis, the opponent is requiring that the proponent defends his statement.