The Long and Winding Road: Forty Years of Argumentation

Trevor Bench-Capon (University of Liverpool)

In this talk I review my engagement with argumentation over the past forty years. I describe the perspective I brought from philosophy and the Civil Service, and consider a number of aspects of computational argumentation: knowledge based systems, explanation, context, audiences, schemes and models. A key feature of argumentation is that it is an activity which has to be actively engaged with, whereas a proof is an object to be understood and admired.

Formal Dialectic: From Aristotle to Pragma-Dialectics, and Beyond

Erik Krabbe (University of Groningen)

Formal dialectic has its roots in ancient dialectic. We can trace this influence in Charles Hamblin's book on fallacies, in which he introduced his first formal dialectical systems. Earlier, Paul Lorenzen proposed systems of dialogical logic, which were in fact formal dialectical systems avant la lettre, with roles similar to those of the Greek Questioner and Answerer. In order to make a comparison between ancient dialectic and contemporary formal dialectic, I shall formalize part of the Aristotelian procedure for Academic debates. The resulting system will be compared with a particular formal dialectic system: Van Eemeren and Grootendorst's rules of Critical Discussion (the pragma-dialectical discussion procedure), which must, however, first itself be reconstructed as a formal dialectical system. When drawing comparisons, it will become clear that there is a line from Aristotle through formal dialectic and pragma-dialectics to computational models of argument.

Multiple logics within argument: how defeasible and classical reasoning work together

Keith Stenning (Universities of Edinburgh and Giessen)

In the psychology lab we often see undergraduates interpreting instructions and materials in nonmonotonic logics when the experimenter intends them to be interpreted in classical logic (Stenning and van Lambalgen 2008). In ongoing experiments we see a larger proportion of reasoners adopting a classical logical interpretation of the task when it is clearly signalled through social discourse cues. This accumulating evidence supports the view that several logics are involved in peoples' reasoning. This talk will raise questions about the implications of such a multiple-logics view of cognition for theories of argumentation using examples drawn from conversation and from legal institutionalisation.

Stenning and van Lambalgen (2008) Human Reasoning and Cognitive Science. MIT Press.