Types of Dialogue, Dialectical Shifts and Fallacies*

The critical discussion is clearly a major context of dialogue to use as a normative model in evaluating arguments as fallacious or not.1 However, this paper will study other types of dialogue that cluster around the edges of the critical discussion. It is a thesis of this paper that these peripheral models of dialogue are needed to support evaluations of arguments as fallacious or non-fallacious. A second thesis is that dialectical shifts, changes from one context of dialogue to another, are vitally important in the job of evaluating whether a given argument is fallacious or not. Previously the present author has, both jointly with John Woods in a series of papers on the fallacies,2 and more recently in his own works,3 advocated this pluralistic view that argumentation needs to be judged as correct or incorrect in relation to a multiplicity of different models of reasoned dialogue.4 It will be shown in Walton and Krabbe (1992) how some important types of dialogue that are major contexts for argumentation can be reduced to a typology of six basic types of dialogue. 1. TYPES OF DIALOGUE A dialogue is an exchange of speech acts between two speech partners in turn-taking sequence aimed at a collective goal. The dialogue is coherent to the extent that the individual speech acts fit together to contribute to this goal. As well, each participant has an individual goal in the dialogue, and both participants have an obligation in the dialogue, defined by the nature of their collective and individual goals. In some dialogues, the goal is to prove something, and in this type of dialogue, a primary obligation is the burden of proof. A burden of proof is a weight of presumption allocated, ideally at the opening stage of the dialogue, set for practical purposes to facilitate the successful carrying out of the obligations of the participants during the course of the dialogue.5 The device of burden of proof is useful because it enables discussion to come to an end in a reasonable time. One important type of dialogue is the critical discussion, well described by van Eemeren and Grootendorst (1984), which is a type of persuasion dialogue, meaning that the goal of each party is to persuade the other party