Douglas Walton - Goal-based Reasoning for Argumentation

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Douglas Walton 2015

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First published 2015

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For Karen, with love

All of the chapters in this book have benefited enormously from many discussions and collaborative research projects with colleagues working in the field of artificial intelligence in computer science, and with my fellow members of CRRAR (the Centre for Research in Reasoning, Argumentation, and Rhetoric) at the University of Windsor. Without the support and inspiration provided by these colleagues over the last decade, my continuing research over this period, which culminated in this book, would not have been possible. It will be readily evident to the reader how much the theory of practical reasoning put forward in the book owes to my collaborative work with Tom Gordon. Work and discussions over the past years with Henry Prakken and Chris Reed on argumentation models of artificial intelligence have also influentially guided my views, helped to solve many problems, and shown ways forward.

For discussions on the subject of value-based practical reasoning during our collaborative work on subjects treated in is a substantially revised version of an article, Practical Reasoning in Health Product Ads, originally published in the journal Argument and Computation (1(3), 2010, 179198). I would like to thank Taylor and Francis for permission to reprint the material in this article.

I would like to thank Floris Bex, Tom Gordon, Henry Prakken, and Bart Verheij for many helpful discussions on the subjects treated in was helped and inspired by my collaborative research work with Fabrizio Macagno and Giovanni Sartor.

I would like to thank Giovanni Sartor for making it possible to work with him on a joint project on argumentation and artificial intelligence at the European University Institute in Florence in 2012 (funded by a Fernand Braudel Research Fellowship). I would also like to thank Eddo Rigotti and Andrea Rocci for organizing The Thematic School on Practical Reasoning, held at the University of Lugano, November 2830, 2012. Additionally, I would like to thank Thomas Roth-Berghofer, Nava Tintarev, and David B. Leake for organizing the ExaCt 2009 Workshop on Explanation-Aware Computing, which took place at the 2009 International Joint Conference on Artificial Intelligence (IJCAI 2009) Workshop in Pasadena, July 1112, 2009. My thanks are also due to Thomas Roth-Berghofer, David B. Leake, and Jrg Cassens for organizing the ExaCt 2011 Workshop on Explanation-Aware Computing, which took place at the 20th European Conference on Artificial Intelligence (ECAI 2012) in Montpellier on July 28, 2012. For helpful discussions I would like to thank Marcin Koszowy, Erik Krabbe, Henry Prakken, Chris Reed, Bart Verheij, and Simon Wells.

I would like to thank the Social Sciences and Humanities Research Council of Canada for support of the research in this book by Insight Grant 435-2012-0104 on the Carneades Argumentation System (held jointly with Tom Gordon). Finally, I would like to thank Rita Campbell for composing the index and helping with proofreading.

Practical reasoning of the kind described by philosophers since Aristotle (384322 BC) is identified as goal-based reasoning that works by finding a sequence of actions that leads toward or reaches an agents goal. Practical reasoning, as described in this book, is used by an agent to select an action from a set of available alternative actions the agent sees as open in its given circumstances. A practical reasoning agent can be a human or an artificial agent for example, software, a robot, or an animal. Once the action is selected as the best or most practical means of achieving the goal in the given situation, the agent draws a conclusion that it should go ahead and carry out this action. Such an inference is fallible, as long as the agents knowledge base is open to new information. It is an important aspect of goal-based practical reasoning that if an agent learns that its circumstances or its goals have changed and a different action might now become the best one available, it can (and perhaps should) change its mind.

In computer science, practical reasoning is more likely to be known as means-end reasoning (where an end is taken to mean a goal), goal-based reasoning, or goal-directed reasoning (Russell and Norvig, ) take values into account.

and shows how they lead forward to the work of the subsequent chapters.