Poles Apart : Navigating the Space of Opinions in Argumentation

Formal argumentation is a popular reasoning method in knowledge representation for intelligent systems. For the past 20 years it has been based on Dung’s abstract argumentation theory. More recently several challenges have been made to this standard - for example in dynamics and aggregation of argumentation frameworks. To support these new developments in this thesis new foundations are developed based on distance measures. We introduce postulates for distance measures and we show their consistency by constructing concrete measures. In the process we develop the new notion of issue. Subsequently we use the distance measures in argumentation using distance based operators introduced by Miller and Osherson in judgment aggregation. Moreover in this thesis we also improve dialectical proof procedures for grounded semantics and study postulates of non-interference and crash resistance for Dung based non-monotonic inference.