During the last decade Argumentation has been gaining importance within Artificial Intelligence especially in multi agent systems. Argumentation is a powerful mechanism for modelling the internal reasoning of an agent. It also provides tools for analysing, designing and implementing sophisticated forms of interaction among rational agents, thus making important contributions to the theory and practice of multiagent dialogues. Application domains include: nonmonotonic reasoning, legal disputes, business negotiation, labor disputes, team formation, scientific inquiry, deliberative democracy, ontology reconciliation, risk analysis, scheduling, and logistics.

This volume presents the latest developments in this area at the interface of argumentation theory and multi agent systems. The 10 revised full papers presented together with 3 invited papers from the AAMAS 2008 conference were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on argument-based reasoning, argumentation and dialogue, as well as strategic and pragmatic issues."

This volume is based on the Second Workshop on Argumentation in Multiagent Systems (Argmas). The workshop was held in conjunction with the 4th Int- national Conference on Autonomous Agents and Multiagent Systems (aamas), at the University of Utrecht in Utrecht, The Netherlands, in July 2005. The workshop itself took place on July 26. We are happy to report that the second workshop was just as popular and successfulasitspredecessor, heldtheprevioussummerinNewYork.Wereceived 17 submissions, eachof which wasreviewed by at least three experts in the ?eld, and ten of these papers were accepted for presentation at the workshop. Once again the workshop was graced by an invited lecture, this time by Frans van Eemeren of the University of Amsterdam, who talked on the subject of prag- dialectics. The workshop attracted 31 participants, ensuring many questions for the speakers, and a healthy exchange of views during the discussion periods. Following the practice established with the post-proceedings of the ?rst Argmasworkshop, weinvitedthepresentersofalltheacceptedpaperstoprepare revised versions of their papers for this volume. In addition we approached - thors of papers on directly related topics that had been presented in theaamas conference, and this gaveus an additionalseven papers. We further solicited one additional paper (details below) and were lucky enough that Prof. van Eemeren consented to send us a paper that covered the material of his invited tal

The theory of argumentation is a rich, interdisciplinary area of research lying across philosophy, communication studies, linguistics, and psychology (at least). Its techniques and results have found a wide range of applications in both t- oretical and practical branches of arti?cial intelligence and computer science. Several theories of argumentation with various semantics have been proposed in the literature. Multi-agent systems theory has picked up argument-inspired approaches and speci?cally argumentation-theoretic results from many di?erent areas. The community of researchers in argumentation and multi-agent systems is currently presented with a unique opportunity to integrate the various und- standings of argument into a coherent and core part of the functioning of - tonomouscomputationalsystems.Thebene?tsrangefromextendedsemanticsof arguments construed as relationships between epistemic atoms, through conv- sation protocols for argumentation with serendipitous information exchange, to models of dialectical practical reasoning, both intra- and inter-agent (and a m- ture of the two). In all these cases argumentation is used to structure knowledge representation, reasoning and agent interaction, and o?ers a potential means of better integrating these disparate problems.