Agreeing to Differ: Modelling Persuasive Dialogue Between Parties With Different Values

Abstract

In some cases of disagreement, particularly in ethics and law, it is impossible to provide any conclusive demonstration. The role of argument in such cases is to persuade rather than to prove. Drawing on ideas ofPerelrnan, we argue that persuasion in such cases relies on a recognition that the strength of such arguments will vary according to their audience, and depends on the comparative weight that the audiences gives to the social values that it advances. To model this, we introduce the notion of Value-based Argumentation Frameworks (VAFs), an extension of Argumentation Frameworks as originally introduced by Dung. We then describe a dialogue game based on VAFs, designed to model persuasive argumentation, which we illustrate with a widely discussed ethical problem.