. While courts depend on expert opinions in reaching sound judgments, the role of the expert witness in legal proceedings is associated with a litany of problems. Perhaps most prevalent is the question of under what circumstances should testimony be admitted as expert opinion. We review the changing policies adopted by American courts in an attempt to ensure the reliability and usefulness of the scientific and technical information admitted as evidence. We argue that these admissibility criteria are best seen in (...) a dialectical context as a set of critical questions of the kind commonly used in models of argumentation. (shrink)

SummaryThis paper outlines a three‐part analysis of the traditional informal fallacy of ad ignorantiam. As initially characterized, the fallacy consists in arguing that failure to prove falsity implies the truth of a proposition.First, the fallacy is located within confirmation theory as a confusion between the categories of “lack of confirming evidence” and “presence of disconfirming evidence”. Second, the structure of the fallacy can be seen as an illicit negation shift in Hintikka‐style epistemic logic. Third, the fallacy can be studied as (...) an attempt to unfairly shift the burden of proof in a dialectical game. We suggest that research on ad ignorantiam needs a broadening of the scope of philosophical logic to encompass concepts of correct argument in these three contexts. (shrink)

This paper studies the modelling of legal reasoning about evidence within general theories of defeasible reasoning and argumentation. In particular, Wigmore's method for charting evidence and its use by modern legal evidence scholars is studied in order to give a formal underpinning in terms of logics for defeasible argumentation. Two notions turn out to be crucial, viz. argumentation schemes and empirical generalisations.

Fundamentals of Critical Argumentation presents the basic tools for the identification, analysis, and evaluation of common arguments for beginners. The book teaches by using examples of arguments in dialogues, both in the text itself and in the exercises. Examples of controversial legal, political, and ethical arguments are analyzed. Illustrating the most common kinds of arguments, the book also explains how to evaluate each kind by critical questioning. Douglas Walton shows how arguments can be reasonable under the right dialogue (...) conditions by using critical questions to evaluate them. The book teaches by example, both in the text itself and in exercises, but it is based on methods that have been developed through the author's thirty years of research in argumentation studies. (shrink)

Second edition of the introductory guidebook to the basic principles of constructing sound arguments and criticising bad ones. Non-technical in approach, it is based on 186 examples, which Douglas Walton, a leading authority in the field of informal logic, discusses and evaluates in clear, illustrative detail. Walton explains how errors, fallacies, and other key failures of argument occur. He shows how correct uses of argument are based on sound strategies for reasoned persuasion and critical responses. This edition (...) takes into account many developments in the field of argumentation study that have occurred since 1989, many created by the author. Drawing on these developments, Walton includes and analyzes 36 new topical examples and also brings in work on argumentation schemes. Ideally suited for use in courses in informal logic and introduction to philosophy, this book will also be valuable to students of pragmatics, rhetoric, and speech communication. (shrink)

Media argumentation is a powerful force in our lives. From political speeches to television commercials to war propaganda, it can effectively mobilize political action, influence the public, and market products. This book presents a new and systematic way of thinking about the influence of mass media in our lives, showing the intersection of media sources with argumentation theory, informal logic, computational theory, and theories of persuasion. Using a variety of case studies that represent arguments that typically occur in the mass (...) media, Douglas Walton demonstrates how tools recently developed in argumentation theory can be usefully applied to the identification, analysis, and evaluation of media arguments. He draws upon the most recent developments in artificial intelligence, including dialogical theories of argument, which he developed, as well as speech act theory. Each chapter presents solutions to problems central to understanding, analyzing, and criticizing media argumentation. (shrink)

Argumentation, which can be abstractly defined as the interaction of different arguments for and against some conclusion, is an important skill to learn for everyday life, law, science, politics and business. The best way to learn it is to try it out on real instances of arguments found in everyday conversational exchanges and legal argumentation. The introductory chapter of this book gives a clear general idea of what the methods of argumentation are and how they work as tools that can (...) be used to analyze arguments. Each subsequent chapter then applies these methods to a leading problem of argumentation. Today the field of computing has embraced argumentation as a paradigm for research in artificial intelligence and multi-agent systems. Another purpose of this book is to present and refine tools and techniques from computing as components of the methods that can be handily used by scholars in other fields. (shrink)

Recent work in artificial intelligence has increasingly turned to argumentation as a rich, interdisciplinary area of research that can provide new methods related to evidence and reasoning in the area of law. Douglas Walton provides an introduction to basic concepts, tools and methods in argumentation theory and artificial intelligence as applied to the analysis and evaluation of witness testimony. He shows how witness testimony is by its nature inherently fallible and sometimes subject to disastrous failures. At the same (...) time such testimony can provide evidence that is not only necessary but inherently reasonable for logically guiding legal experts to accept or reject a claim. Walton shows how to overcome the traditional disdain for witness testimony as a type of evidence shown by logical positivists, and the views of trial sceptics who doubt that trial rules deal with witness testimony in a way that yields a rational decision-making process. (shrink)

Media argumentation is a powerful force in our lives. From political speeches to television commercials to war propaganda, it can effectively mobilize political action, influence the public, and market products. This book presents a new and systematic way of thinking about the influence of mass media in our lives, showing the intersection of media sources with argumentation theory, informal logic, computational theory, and theories of persuasion. Using a variety of case studies that represent arguments that typically occur in the mass (...) media, Douglas Walton demonstrates how tools recently developed in argumentation theory can be usefully applied to the identification, analysis, and evaluation of media arguments. (shrink)

This chapter proposes a dialectical approach to legal interpretation, consisting of three dimensions: a formalization of the canons of interpretation in terms of argumentation schemes; a dialectical classification of interpretive schemes; and a logical and computational model for comparing the arguments pro and contra an interpretation. The traditional interpretive maxims or canons used in both common and civil law are translated into defeasible patterns of arguments, which can be evaluated through sets of corresponding critical questions. These interpretive argumentation schemes are (...) classified in general categories and a distinction is drawn between schemes supporting and rebutting an interpretation. This framework allows conceiving statutory interpretation as a dialectical procedure consisting in weighing arguments pro and contra an interpretation. This procedure is formalized and represented computationally through tools from formal argumentation systems. (shrink)

Wigmore thought that there was a science of proof underlying legal reasoning that could be displayed in any given case as a graphic sequence of argumentation from the evidence in the case leading to the ultimate probandum. Argumentation technology has now vindicated this approach by providing useful qualitative methods that can be applied to identifying, analyzing, and evaluating the pro and con arguments put forward by both sides in a trial. In this chapter, it is shown how to apply argumentation (...) schemes, such as argument from witness testimony, using argument diagrams applied to typical sequences of evidence-based legal reasoning in which there is a successive refinement of arguments displayed as the evidence comes into a case. It is shown how argument from applying rules to cases, teleological, argument from expert witness testimony, and abductive reasoning are centrally important for this purpose. (shrink)

Synthese: An International Journal for Epistemology, Logic and Philosophy of Science, 157, 2007, 197-240. Published version available at: http://www.springerlink.com/content/q9402gv46t415504/fulltext.pdf.

Develops a logical analysis of dialogue in which two or more parties attempt to advance their own interests. It includes a classification of the major types of dialogues and a discussion of several important informal fallacies.

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

INTRODUCTION BY THE EDITORS Gilbert Ryle, in his Concept of Mind (1949), attacked volitional theories of human actions; JL Austin, in his "If and Cans" ...

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

This book identifies 25 argumentation schemes for presumptive reasoning and matches a set of critical questions to each.

Although fallacies have been common since Aristotle, until recently little attention has been devoted to identifying and defining them. Furthermore, the concept of fallacy itself has lacked a sufficiently clear meaning to make it a useful tool for evaluating arguments. Douglas Walton takes a new analytical look at the concept of fallacy and presents an up-to-date analysis of its usefulness for argumentation studies. Walton uses case studies illustrating familiar arguments and tricky deceptions in everyday conversation where the (...) charge of fallaciousness is at issue. The numerous case studies show in concrete terms many practical aspects of how to use textual evidence to identify and analyze fallacies and to evaluate arguments as fallacious. Walton looks at how an argument is used in the context of conversation. He defines a fallacy as a conversational move, or sequence of moves, that is supposed to be an argument that contributes to the purpose of the conversation but in reality interferes with it. The view is a pragmatic one, based on the assumption that when people argue, they do so in a context of dialogue, a conventionalized normative framework that is goal-directed. Such a contextual framework is shown to be crucial in determining whether an argument has been used correctly. Walton also shows how examples of fallacies given in the logic textbooks characteristically turn out to be variants of reasonable, even if defeasible or questionable arguments, based on presumptive reasoning. This is the essence of the evaluation problem. A key thesis of the book, which must not be taken for granted as previous textbooks have so often done, is that you can spot a fallacy from how it was used in a context of dialogue. This is an innovative and even, as Walton notes, "a radical and controversial" theory of fallacy. (shrink)

Argument from analogy is a common and formidable form of reasoning in law and in everyday conversation. Although there is substantial literature on the subject, according to a recent survey ( Juthe 2005) there is little fundamental agreement on what form the argument should take, or on how it should be evaluated. Th e lack of conformity, no doubt, stems from the complexity and multiplicity of forms taken by arguments that fall under the umbrella of analogical reasoning in argumentation, dialectical (...) studies, and law. Modeling arguments with argumentation schemes has proven useful in attempts to refine the analyst’s understanding of not only the logical structures that shape the backbone of the argument itself, but also the logical underpinning of strategies for evaluating it, strategies based on the semantic categories of genus and relevance. By clarifying the distinction between argument from example and argument from analogy, it is possible to advance a useful proposal for the treatment of argument from analogy in law. (shrink)

This is an introductory guide to the basic principles of constructing good arguments and criticizing bad ones. It is nontechnical in its approach, and is based on 150 key examples, each discussed and evaluated in clear, illustrative detail. The author explains how errors, fallacies, and other key failures of argument occur. He shows how correct uses of argument are based on sound argument strategies for reasoned persuasion and critical questions for responding. Among the many subjects covered are: techniques of posing, (...) replying to, and criticizing questions, forms of valid argument, relevance, appeals to emotion, personal attack, uses and abuses of expert opinion, problems in deploying statistics, loaded terms, equivocation, and arguments from analogy. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy and Rhetoric 33.2 (2000) 101-115 [Access article in PDF] Case Study of the Use of a Circumstantial Ad Hominem in Political Argumentation Douglas Walton In the 1860s, Northern newspapers attacked Lincoln's policies by attacking his character, using the terms drunk, baboon, too slow, foolish, and dishonest. Steadily on the increase in political argumentation since then, the argumentum ad hominem has been carefully refined as an instrument (...) of "oppo tactics" and "going negative" by the public relations experts who now craft political campaigns at the national level. It has been so prominently used in the major political campaigns, debates, and advertisements of the past few years that there has even been a reaction against it--a feeling that we have gone too far in this direction and that some kind of restraint is needed. 1 But there has been no evidence of such restraint in the argumentation used in recent campaigns. Perhaps what might be helpful is a better understanding on the part of voters and campaigners of how to evaluate ad hominem arguments critically.How does the ad hominem argument really work as a way of molding public opinion, why is it so often so effective, and how can it be defended against? How can it be evaluated as a clearly identifiable type of argument, by some kind of objective standards, in a way that can be applied to particular cases? These appear to be tough questions, but recent research has made some not inconsiderable progress toward answering them.The purpose of this article is to present a new case study of a type of argument commonly used in political discourse, a case study that makes use of the dialectical normative framework for identifying and evaluating personal attack (ad hominem) arguments that is developed in a series of works by Henry W. Johnstone Jr. (1952); Alan Brinton (1985, 1995); Frans H. van Eemeren and Rob Grootendorst (1984, 1995); Erik C. W. Krabbe and Douglas N. Walton (1993), Walton (1989, chap. 6; 1998); and van Eemeren, Grootendorst, Francisca Snoeck Henkemans et al. (1996). This particular case, although typical of so many ad hominem arguments currently [End Page 101] in use in political discourse, has some special features that turn out to be quite interesting not only in showing how the dialectical framework applies to cases, but also in advancing our knowledge of how the ad hominem type of argument works in political argumentation in a democratic system for which the media reportage of events is a big factor in influencing voting. 1. Framework for analysis and evaluation Although the argumentum ad hominem, or personal attack argument, has been traditionally treated as a fallacy in logic, recent research in argumentation (as cited above) shows that, in many cases,--including cases in political argumentation--ad hominem arguments, as used in conversational arguments, are not fallacious. Research has shown that, while some personal attack arguments can definitely be judged fallacious, many others are quite reasonable (when evaluated in the appropriate context), while still others should be evaluated as weak (insufficiently supported) but not fallacious. As shown in this case study, the real function of an ad hominem argument (when properly used) is to attack an arguer's credibility in order to criticize the argument she advocates.Before going any further, it is necessary to define some terminology brought to use in the research cited above. An ad hominem argument is the use of personal attack in a dialogue exchange between two parties, where the one party attacks the character of the other party as bad, in some respect, and then uses this attack as a basis for criticizing the other party's argument. An argument is fallacious if it is a special baptizable (Johnson 1987) type of argument that is used by one party in a dialogue exchange in such a way that it blocks or interferes with the collaborative realization of the goal of the type of dialogue in which the two participants are supposed to be engaged (Walton 1995). Thus, there is a difference between a weak... (shrink)

A new pragmatic approach, based on the latest developments in argumentation theory, analyzing appeal to expert opinion as a form of argument. Reliance on authority has always been a common recourse in argumentation, perhaps never more so than today in our highly technological society when knowledge has become so specialized—as manifested, for instance, in the frequent appearance of "expert witnesses" in courtrooms. When is an appeal to the opinion of an expert a reasonable type of argument to make, and when (...) does it become a fallacy? This book provides a method for the evaluation of these appeals in everyday argumentation. Specialized domains of knowledge such as science, medicine, law, and government policy have gradually taken over as the basis on which many of our rational decisions are made daily. Consequently, appeal to expert opinion in these areas has become a powerful type of argument. Challenging an argument based on expert scientific opinion, for example, has become as difficult as it once was to question religious authority. Walton stresses that even in cases where expert opinion is divided, the effect of it can still be so powerful that it overwhelms an individual's ability to make a decision based on personal deliberation of what is right or wrong in a given situation. The book identifies the requirements that make an appeal to expert opinion a reasonable or unreasonable argument. Walton's new pragmatic approach analyzes that appeal as a distinctive form of argument, with an accompanying set of appropriate critical questions matching the form. Throughout the book, a historical survey of the key developments in the evolution of the argument from authority, dating from the time of the ancients, is given, and new light is shed on current problems of "junk science" and battles between experts in legal argumentation. (shrink)

The paper considers contemporary models of presumption in terms of their ability to contribute to a working theory of presumption for argumentation. Beginning with the Whatelian model, we consider its contemporary developments and alternatives, as proposed by Sidgwick, Kauffeld, Cronkhite, Rescher, Walton, Freeman, Ullmann-Margalit, and Hansen. Based on these accounts, we present a picture of presumptions characterized by their nature, function, foundation and force. On our account, presumption is a modal status that is attached to a claim and has (...) the effect of shifting, in a dialogue, a burden of proof set at a local level. Presumptions can be analysed and evaluated inferentially as components of rule-based structures. Presumptions are defeasible, and the force of a presumption is a function of its normative foundation. This picture seeks to provide a framework to guide the development of specific theories of presumption. (shrink)

Walton gives a clear method for analyzing and evaluating cases of ad hominem arguments found in everyday argumentation.

William Baird collection in Social Sciences is the gift of the Estate of William Cameron Baird.

This paper builds a nine-step method for determining whether a straw man fallacy has been committed in a given case or not, by starting with some relatively easy textbook cases and moving to more realistic and harder cases. The paper shows how the type of argument associated with the fallacy can be proved to be a fallacy in a normative argumentation model, and then moves on to the practical task of building a hands-on method for applying the model to real (...) examples of argumentation. Insights from linguistic pragmatics are used to distinguish the different pragmatic processes involved in reconstructing what is said and what is meant by an utterance, and to differentiate strong and weak commitments. In particular, the process of interpretation is analyzed in terms of an abductive pattern of reasoning, based on co-textual and contextual information, and assessable through the instruments of argumentation theory. (shrink)

A leading expert in informal logic, Douglas Walton turns his attention in this new book to how reasoning operates in trials and other legal contexts, with special emphasis on the law of evidence. The new model he develops, drawing on methods of argumentation theory that are gaining wide acceptance in computing fields like artificial intelligence, can be used to identify, analyze, and evaluate specific types of legal argument. In contrast with approaches that rely on deductive and inductive logic (...) and rule out many common types of argument as fallacious, Walton’s aim is to provide a more expansive view of what can be considered "reasonable" in legal argument when it is construed as a dynamic, rule-governed, and goal-directed conversation. This dialogical model gives new meaning to the key notions of relevance and probative weight, with the latter analyzed in terms of pragmatic criteria for what constitutes plausible evidence rather than truth. (shrink)

This is an introductory guidebook to the basic principles of how to construct good arguments and how to criticeze bad ones. It is non-technical in its approach and is based on 150 key examples, each discussed and evaluated in clear, illustrative detail. Professor Walton, a leading authority in the field of informal logic, explains how errors, fallacies, and other key failures of argument occur. He shows how correct uses of argument are based on sound strategies for reasoned persuasion and (...) critical responses. Among the many subjects covered are: forms of valid argument, relevance, appeals to emotion, personal attack, uses and abuses of expert opinion, problems in deploying statistics, loading terms, equivocation, arguments from analogy, and techniques of posing, replying to, and criticizing questions. The book will be ideally suited to courses in informal logic and in the introduction to philosophy. It will also prove valuable to studetns of pragmatics, rhetoric, and speech communication. (shrink)

Appeals to emotion—pity, fear, popular sentiment, and _ad hominem_ attacks—are commonly used in argumentation. Instead of dismissing these appeals as fallacious wherever they occur, as many do, Walton urges that each use be judged on its merits. He distinguished three main categories of evaluation. First, is it reasonable, even if not conclusive, as an argument? Second, is it weak and therefore open to critical questioning for argument? And third, is it fallacious? The third category is a strong charge that (...) incurs a critical burden to back it up by citing evidence from the given text and context of dialogue. Walton uses fifty-six case studies to demonstrate that the problem of emotional fallacies is much subtler than has been previously believed. Ranging over commercial advertisements, political debates, union-management negotiations, and ethical disputes, the case studies reveal that these four types of appeals, while based on presumptive reasoning that are tentative and subject to default, are not always or necessarily fallacious types of argumentation. (shrink)

_Arguments from Ignorance _explores the situations in which the argument from ignorance functions as a respectable form of reasoning and those in which it is indeed fallacious. Douglas Walton draws on everyday conversations on all kinds of practical matters in which the _argumentum ad ignorantiam _is used quite appropriately to infer conclusions. He also discusses the inappropriate use of this kind of argument, referring to various major case studies, including the Salem witchcraft trials, the McCarthy hearings, and the (...) Alger Hiss case. This book makes an original contribution in the areas of argumentation theory and informal logic, contending that, despite its traditional classification as a fallacy, the argument from ignorance is a genuine, very common, and legitimate type of argumentation with an identifiable structure. But the book is also interdisciplinary in scope, explaining many widely interesting and controversial subjects in artificial intelligence, medical education, philosophy of science, and philosophy of law in a clear way that makes it accessible to a broad range of readers. (shrink)

This paper uses the language of formal dialectics to explore how argumentation schemes and their critical questions can be characterized as an extension to traditional dialectical systems. The aim is to construct a dialectical system in which the set of locutions is extended to include scheme-based moves the set of structural rules describes the roles that critical questioning can play; and the set of commitment rules distinguishes between exceptions and assumptions.

This book analyzes the uses of emotive language and redefinitions from pragmatic, dialectical, epistemic and rhetorical perspectives, investigating the relationship between emotions, persuasion and meaning, and focusing on the implicit dimension of the use of a word and its dialectical effects. It offers a method for evaluating the persuasive and manipulative uses of emotive language in ordinary and political discourse. Through the analysis of political speeches and legal arguments, the book offers a systematic study of emotive language in argumentation, rhetoric, (...) communication, political science and public speaking. (shrink)

A "slippery slope argument" is a type of argument in which a first step is taken and a series of inextricable consequences follow, ultimately leading to a disastrous outcome. Many textbooks on informal logic and critical thinking treat the slippery slope argument as a fallacy. Walton argues that used correctly in some cases, they can be a reasonable type of argument to shift a burden of proof in a critical discussion, while in other cases they are used incorrectly. (...) class='Hi'>Walton identifies and analyzes four types of slippery slope argument. Walton presents guidelines that show how each type of slippery slope argument can be used correctly or incorrectly, using over fifty case studies of argumentation on controversial issues. These include abortion, medical research on human embryos, euthanasia, the decriminalization of marijuana, pornography, and censorship, and banning of American flag burning. (shrink)

This book offers a new theory of begging the question as an informal fallacy, within a pragmatic framework of reasoned dialogue as a normative theory of critical argumentation. The fallacy of begging the question is analyzed as a systematic tactic to evade fulfillment of a legitimate burden of proof by the proponent of an argument. The technique uses a circular structure of argument to block the further progress of dialogue and, in particular, the capability of the respondent to ask legitimate (...) critical questions in reply to the argument. Walton analyzes the concept of burden of proof in argument, and provides chapters on the use of argument diagramming as a technique of argument reconstruction. This powerful method of argument analysis developed therein is then applied to more than 100 case studies of circular argumentation where the charge of begging the question is or has been thought to be an appropriate criticism. Throughout this work, Walton throws light on the relationship between the problem of circular reasoning and broader issues in the critical analysis of argumentation. Ground-breaking use is made of the pragmatic theory of argument as interactive dialogue. Rules for several kinds of dialogue framework provide standards of good reasoning to validate or to refute the criticism that a particular argument begs the question. This book is directed to students and professionals in the fields of speech communication, philosophy, linguistics, logic, dispute mediation, and education. (shrink)

A Bibliography of Douglas Walton’s Published Works, 1971-20.

This book examines three areas in which abductive reasoning is especially important: medicine, science, and law. The reader is introduced to abduction and shown how it has evolved historically into the framework of conventional wisdom in logic. Discussions draw upon recent techniques used in artificial intelligence, particularly in the areas of multi-agent systems and plan recognition, to develop a dialogue model of explanation. Cases of causal explanations in law are analyzed using abductive reasoning, and all the components are finally brought (...) together to build a new account of abductive reasoning. By clarifying the notion of abduction as a common and significant type of reasoning in everyday argumentation, _Abductive Reasoning_ will be useful to scholars and students in many fields, including argumentation, computing and artificial intelligence, psychology and cognitive science, law, philosophy, linguistics, and speech communication and rhetoric. (shrink)

In redefining logic, philosophers need to go back to the Aristotelian roots of the subject, to expand the boundaries of the subject to include informal logic and to give up false oppositions between informal and formal logic.

This book provides a practical and accessible way of evaluating good and bad arguments used in everyday conversations by applying normative models of dialectical (interactive) argumentation, where two parties reason together in an orderly and cooperative way. Using case studies, the author analyzes correct and incorrect uses of argumentation on controversial issues that engage the reader's interest while illustrating points in a practical way. Walton gives clear explanations of the most common errors and tricky deceptions -- traditionally called "fallacies" (...) -- that can trip up an unwary arguer. (shrink)

Vol. presents a method for critically evaluating relevance in arguments based on case studies & a new relevance theory incorporating techniques of argumentation theory, logic & artificiaI intelligence. For scholars/students in argumentation & rhetoric.