Sanjay Modgil: Dialectical Formalizations of Non-monotonic Reasoning: Rationality under Resource Bounds
Abstract
ASPIC+ is a widely used framework that provides for dialectical formalizations of non-monotonic logics. That is to say, the non-monotonic inferences defined by sets of formulae can equivalently be defined in terms of the claims of arguments that successfully defend themselves against counter-arguments. ASPIC+ provides guidelines for ensuring that any such dialectical formalization yields rational outcomes; notably, that the claims of winning arguments are mutually consistent. However, rationality in this sense is guaranteed only under the assumption that agents are logically omniscient (i.e., they have unbounded resources). Moreover, ASPIC+ is not fully rational, in the sense that given a set of formulae A, then the argumentation defined inferences from A may be retracted when adding some set B that is syntactically disjoint from A (a problem known as contamination). In this talk I will present a new version of ASPIC+ that adopts a radically new notion of argument and counter-argument, and that can be shown to be fully rational under resource bounds. This then means that resource bounded agents can now reason non-monotonically, as individuals or jointly via dialogue, while guaranteeing rational outcomes. This is joint work with Professor Marcello D’Agostino at the Department of Philosophy, University of Milan.
Short Bio
Sanjay Modgil is a senior lecturer at King’s College London. His primary area of research is in argumentation theory. His key contributions in this area include: 1) the ASPIC+ framework and its provision of dialectical characterisations of non-monotonic reasoning for single agent inference and distributed reasoning in the form of multi-agent dialogues; 2) extensions to the standard model of argumentation so as to accommodate reasoning about (possibly conflicting) preferences and values, and application of these extensions to ethical and moral reasoning. More recently, his focus has been on graded generalisations of Dung’s theory of argumentation, and dialectical formalisations of non-monotonic reasoning that are provably rational under resource bounds.