Local logics, non-monotonicity and defeasible argumentation

In this paper we present an embedding of abstract argumentation systems into the framework of Barwise and Seligman's logic of information flow. We show that taking P.M. Dung's characterization of argument systems a local logic over states of a deliberation may be constructed. In this structure the key feature of non-monotonicity of commonsense reasoning obtains as the transition from one local logic to another due to a change in certain background conditions. Each of Dung's extensions of argument systems leads to a corresponding ordering of background conditions. The relations among extensions becomes a relation among partial orderings of background conditions. This introduces a conceptual innovation in Barwise and Seligman's representation of commonsense reasoning. © 2005 Springer Science + Business Media Inc.