Profiles of Dialogue for Evaluating Arguments from Ignorance

The argument from ignorance is a hard type of argumentation to evaluate using the profile of dialogue as a tool, because parts of the argumentation are responses that do not occur in the sequence of exchanges. The argument from ignorance works as an inference because implications are drawn from what was not said. This feature poses a difficulty for the profile of dialogue method. And in fact, what will be done to cope with this problem is to introduce so-called negative profiles of dialogue. Another difficulty is that arguments from ignorance are very often The argumentum ad ignorantiam, usually called 'appeal to ignorance' or 'argument from ignorance' in the logic textbooks, has traditionally been classified as a fallacy (Hamblin, 1970). But a growing climate of recent (1991)-sees this same kind of argumentation, variously called the lack-of-knowledge inference, negative evidence, or negative default reasoning, as nonfallacious. The problem posed then is how to determine, by some clear and useful method, which are the fallacious and which are the nonfallacious cases (Krabbe, 1995; Walton, 1996). Among the new dialectical tools being developed for this purpose is the profile of dialogue (Walton, 1989a; Krabbe, 1992), a means of representing a sequence of connected moves (adjacency-pairs) in a dialogue exchange. ABSTRACT: This investigation uses the technique of the profile of dialogue as a tool for the evaluation of arguments from ignorance (also called lack-of-evidence arguments, negative evidence, ad ignorantiam arguments and ex silentio arguments). Such arguments have traditionally been classified as fallacies by the logic textbooks, but recent research has shown that in many cases they can be used reasonably. A profile of dialogue is a connected sequence of moves and countermoves in a conversational exchange of a type that is goal-directed and can be represented in a normative model of dialogue. Selected case studies are used to probe special features of using the profile technique as applied to arguments from ignorance of a kind that occur frequently in everyday conversational exchanges. One of these special features is the use of Gricean implicature. Another is the need to use negative profiles of argument.