 Argumentation evaluation on the Pragma-dialectical approach is done with an eye to a single ideal model of argumentation. This approach has been challenged by Douglas Walton who has written more about fallacies and fallacy theory than anyone else. He has published individual monographs on many of the well-known fallacies, among them, Begging the Question (1991), Slippery Slope Arguments (1992), Ad Hominem Arguments (1998), and a comprehensive work on fallacy theory, A Pragmatic Theory of Fallacy (1995). Over the years his views have evolved. He has referred to his theory as “the Pragmatic theory,” and like the Pragma-dialectical theory it has a dialectical/dialogical basis; however, Walton envisions a number of distinct normative dialectical frameworks (persuasion dialogue, inquiry dialogue, negotiation dialogue, etc.) rather than the single model of a critical discussion proposed by Pragma-dialectics. Postulating different kinds of dialogues with different starting points and different goals, thinks Walton, will bring argumentation into closer contact with argumentation reality. At one point Walton had the idea that fallacies happened when there was an illicit shift from one kind of a dialogue to another (1995, 118–23), for example, using arguments appropriate for a negotiation dialogue in a persuasion dialogue, but more recently he has turned to other ways of explicating fallacies.