An Introduction to Formal Argumentation
Formal argumentation is a relatively novel approach to the issue of nonmonotonic reasoning. Its main advantage is that it allows entailment to be expressed in terms of a discussion between a proponent and an opponent who exchange arguments regarding the validity of a main claim. That is, the entailment coincides with that which can be defended in a rational discussion, rather than the traditional notion of truth defined in a model-theoretic way. Although argument construction is monotonic (more information leads to the construction of more possible arguments), the overall entailment is not. This is because the new arguments can attack (or reinstate) previous arguments, and influence the status of their conclusions.
The fact that formal argumentation has become an emerging research topic over the last few years (as is witnessed by special issues on argumentation in the Artificial Intelligence journal and the IEEE Intelligent Systems journal) can be contributed to the fact that it is a relatively straightforward way of performing nonmonotonic inference, whose semantics draw upon human debate. Furthermore, several existing formalisms for nonmonotonic reasoning (like Default Logic, Answer Set Programming, Nute's Defeasible Logic, and Pollock's OSCAR) have now been reformulated in the form of formal argumentation.
Martin Caminada has done a PhD on formal argumentation at the Vrije Universiteit Amsterdam, and has afterwards worked on an EU-funded argumentation project. Apart from his teaching obligations at the University of Luxembourg, he has given lectures at ESSLLI and EASSS. His publication record includes AAAI, ECAI and AIJ.