ArgLab • Seminar

Formal Dialectic

Erik C. W. Krabbe & Jan Albert van Laar

The seminar is intended to introduce the participants to formal dialectic – or to enrich the scope of their experience with it. This will be done by studying a number of particular systems of formal dialectic (also known as “dialogue games”). Now, formal dialectic is a formal approach to argumentation and has evidently some affinity to formal logic. Some formal dialectical systems can even be seen as dialectical reformulations of formal logical systems. Nevertheless no special knowledge of logic is required to attend the seminar. Though familiarity with elementary (propositional and predicate) logic will certainly help you to more easily master the concepts, the vocabulary, and the notations used by formal dialecticians, it will not be presupposed that you have much formal logic ready to hand. Some slight acquaintance with the language of propositional logic will suffice.


After a general introduction, we shall study two types of dialogue games: Hamblin games and Lorenzen games. We’ll start with studying the Hamblin games, first of all Hamblin’s own “Why-Because system with questions” (also known as “system H”; Hamblin,1970, pp. 265-272), taking into account a critical observation by Woods & Walton (1989, pp. 147-150). We’ll see how these systems handle problems relating to traditional fallacies such as begging the question and many questions. Second, we zoom in on problems and fallacies that arise from ambiguity, discussing two dialogue systems that aim to provide the discussants with devices with which they can solve their problems of language use (Mackenzie, 1990; Van Laar, 2010). Third, we discuss to what extent a formal dialectical approach can adequately deal with one-sided argumentation (Van Laar, 2007). Fourth, we shall discuss a formal treatment of defeasible argumentation as proposed by Walton, Reed, and Macagno (2008).


In the meantime we shall have started on the Lorenzen games. Different than in Hamblin games, in these games the concept of a winning strategy is of paramount importance. We shall use a system based on syllogistic to illustrate the main features of this type of dialectic system (Krabbe, 2006a), and then go through a number of examples to get a good grasp of the way these games work. Then we shall turn to winning strategies and the method of dialogical tableaux. Finally, we shall discuss the advantages and drawbacks of the Hamblin and the Lorenzen  games and see how one can have the best of both by embedding dialogues of the second type into those of the first type (Walton & Krabbe, 1995).


A reader for the seminar will be available upon registration.


Erik C. W. Krabbe (Professor emeritus of Logic and Philosophical Theory of Argumentation, University of Groningen, the Netherlands)

Jan Albert van Laar (University of Groningen, the Netherlands)