Analyzing the Structure of Argumentative Discourse

Consider a discourse situation where the speaker tries to convince the hearer of a particular point of view. The first task for the hearer is to understand what it is the speaker wants him to believe-to analyze the structure of the argument being presented, before judging credibility and eventually responding. This paper describes a model for the analysis of arguments that includes: • a theory of expected coherent structure which is used to limit analysis to the reconstruction of particular transmission forms; • a theory of linguistic clues which assigns a functional interpretation to special words and phrases used by the speaker to indicate the structure of the argument; • a theory of evidence relationships which includes the demand for pragmatic analysis to accommodate beliefs not currently held. The implications of this particular design for dialogue analysis in general are thus: • structure is an important feature to extract in a representation to control the processing; • linguistic constructions can be assigned useful interpretations; • pragmatic analysis is crucial in cases where the participants differ in beliefs. 1 THE PROBLEM AREA Consider the task of designing an "argument understanding system", a natural language understanding system (NLUS) where the input is restricted to arguments. Consider as well arguments constructed in a dialogue situation, where a speaker (S) tries to convince a hearer (H) of a particular point of view. The hearer patiently listens; hence, the input is "one-way communication". The argument understanding system therefore plays the role of the hearer, and tries to analyze the structure of the argument being presented. This task is isolated as a necessary first step for a hearer, in order to be a successful participant in a conversation. In other words, the hearer must have some representation of what it is the speaker wants him to believe, before judging credibility and eventually responding. Note that this language problem is relatively new and yet feasible. It is distinct from other NLU endeavors, such as story understanding, which appeal to a stereotype of content in order to reduce processing. In arguments, one is never sure what points the speaker will address; content can't be stereotyped. However, arguments have a defining characteristic-they are necessarily goal-oriented. The speaker wants to convince the hearer of some overall point. Thus, there is an overall logical structure to the input and this fact may be used by a hearer to control analysis. For …