Douglas Walton

(? - 2020)

This paper looks around among the major traditional fallacies — centering mainly around the so-called “gang of eighteen” — to discuss which of them should properly be classified as fallacies of relevance. The paper argues that four of these fallacies are fallacies primarily because they are failures of relevance in argumentation, while others are fallacies in a way that is more peripherally related to failures of relevance. Still others have an even more tangential relation to failures of relevance. This paper is part of a larger research project on dialecical relevance in argumentative discourse, currently underway in collaboration with Frans van Eemeren and Rob Grootendorst

In ‘Can and Might’, Professor K. W. Rankin has presented three arguments that purport to refute the equivalence, ‘A is causally possible for P if and only if A is within P's power’. The first two arguments are attributed to Richard Taylor, and the third is Professor Rankin's own. I will argue that none of these three arguments effectively refutes the above equivalence. My arguments are not to be construed as simply a rebuttal of Professor Rankin's paper since he also appears to have some doubts about Taylor's arguments and I refrain from comment on other aspects of his paper except these three arguments. I conclude with some general remarks on.

In the writings of Henry W. Johnstone, Jr. there can be found an evolving and gradually more sophisticated discussion of the relationship between rhetorical and dialectical argument. Johnstone's view on these matters was highly original, and at odds with the prevailing logical empiricism of the time, much like Toulmin's views on argumentation in The Uses of Argument (1958). In view of the rising importance of the issue of the relationship between rhetoric and informal logic, Johnstone's analysis of the argumentum ad hominem, and its relationship to Hamblin's notion of commitment, is especially worth careful consideration

Amphiboly has been widely recognized, starting from the time of Aristotle, as an informal fallacy arising from grammatical ambiguity. This paper applies the profiles of dialogue tool to the fallacy of amphiboly, providing a five-step evidence-based procedure whereby a syntactically ambiguous sentence uttered in a natural language text can be evaluated as committing a fallacy of amphiboly. A user applies the tool to a natural language text by comparing a descriptive graph, representing how the argumentation actually went, to a normative graph, representing how the argumentation should ideally have proceeded.

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.

In his book on fallacies, Hamblin built a very simple system for argumentation in dialogue he called the Why Because System with Questions. In his discussion of this system, he replaced the concept of burden of proof with a simpler concept of initiative, which could be described as something like getting the upper hand as the argumentation moves back and forth in the dialogue between the one party and the other. No doubt he realized that the concept of burden of proof was too complex a matter to be dealt with in the limited scope of his chapter on formal dialogue systems. In this paper is shown how an extended version of Hamblin’s dialogue system provides a nice way of modeling the phenomenon of shifting of burden of proof in a dialogue, yielding a precise way of distinguishing between different kinds of burden of proof, and dealing with fallacies like the argumentum ad ignorantiam.

Use of argumentation methods applied to legal reasoning is a relatively new field of study. The book provides a survey of the leading problems, and outlines how future research using argumentation-based methods show great promise of leading to useful solutions. The problems studied include not only these of argument evaluation and argument invention, but also analysis of specific kinds of evidence commonly used in law, like witness testimony, circumstantial evidence, forensic evidence and character evidence. New tools for analyzing these kinds of evidence are introduced.

It is shown that Aristotelian dialectic can be analyzed as having two parts: a core formal model that has a formal dialogue structure and a set of ten definable supplementary characteristics that lie outside the core structure. Some current argumentation tools used in artificial intelligence and multi-agent systems are applied to the task of extending the core formal model to include the supplementary characteristics. Using these tools it is explained how the structure of a dialogue can be mapped into an argument diagram that can be analyzed and evaluated using standard argumentation techniques such as argumentation schemes, types of dialogue, critical questions and a dialectical concept of burden of proof. Disputed issues on how the elenchus fits the standard dialogue typology are discussed, and it is concluded that it fits best into a type of dialogue called examination dialogue that is closely related to persuasion dialogue.

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

Scare Tactics, the first book on the subject, provides a theory of the structure of reasoning used in fear and threat appeal argumentation. Such arguments come under the heading of the argumentum ad baculum, the `argument to the stick/club', traditionally treated as a fallacy in the logic textbooks. The new dialectical theory is based on case studies of many interesting examples of the use of these arguments in advertising, public relations, politics, international negotiations, and everyday argumentation on all kinds of subjects. Many of these arguments are amusing, once you see the clever tactic used; others are scary. Some of the arguments appear to be quite reasonable, while others are highly suspicious, or even outrageously fraudulent. In addition to the examples taken from logic textbooks, other cases treated come from a variety of sources, including political debates, legal arguments, and arguments from media sources, like magazine articles and television ads. The purpose of this book is to explain how such arguments work as devices of persuasion, and to develop a method for analyzing and evaluating their reasonable and fallacious uses in particular cases. The book shows how such arguments share a common structure, revealing several distinctive forms of argument nested within each other. Based on its account of this cognitive structure, the new dialectical theory presents methods for identifying, analyzing, and evaluating these arguments, as they are used in specific cases. The book is a scholarly contribution to argumentation theory. It is written in an accessible style, and uses many colorful and provocative examples of fear and threat appeal arguments that are suitable for classroom discussions. The matters treated will be of interest to professionals and students in law, critical thinking, advertising, speech communication, informal logic, cognitive science, rhetoric, and media studies.

_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

Arguments from popular opinion have long been regarded with suspicion, and in most logic textbooks the _ad populum _argument is classified as a fallacy. Douglas Walton now asks whether this negative evaluation is always justified, particularly in a democratic system where decisions are based on majority opinion. In this insightful book, Walton maintains that there is a genuine type of argumentation based on commonly accepted opinions and presumptions that should represent a standard of rational decision-making on important issues, especially those of a personal and political nature. He shows how to judge arguments based on appeals to popular opinion in a more balanced way, identifying eleven subtypes of the _ad populum_ argument and providing a pragmatic method to evaluate each of these types. Walton has examined dozens of logic texts and drawn on a wide range of literature to reveal the many uses and misuses of popular opinion. He contrasts the traditional discussion of _ad populum _in Greek rhetoric with recent textbook treatment, then contrasts these contemporary views with his own dialectical perspective in order to clarify often confused appeals to prejudice and appeals to common knowledge. Although appeal to popular opinion has long been a powerful argumentative tactic, this is the first book to systematically describe and evaluate it as a well-defined type of argument with its own special characteristics. It enables us to deal with these often deceptive arguments in a critically balanced way and makes an original contribution to an important strand of rhetoric

This investigation joins recent research on problems with ambiguity in two fields, argumentation and computing. In argumentation, there is a concern with fallacies arising from ambiguity, including equivocation and amphiboly. In computing, the development of agent communication languages is based on conversation policies that make it possible to have information exchanges on the internet, as well as other forms of dialogue like persuasion and negotiation, in which ambiguity is a problem. Because it is not possible to sharply differentiate between problems arising from ambiguity and those arising from vagueness, obscurity and indeterminacy, some study of the latter is included. The semantic web is based on what are called ontologies, or systems of classification of concepts, shown to be useful tools for dealing with these problems.

This monograph poses a series of key problems of evidential reasoning and argumentation. It then offers solutions achieved by applying recently developed computational models of argumentation made available in artificial intelligence. Each problem is posed in such a way that the solution is easily understood. The book progresses from confronting these problems and offering solutions to them, building a useful general method for evaluating arguments along the way. It provides a hands-on survey explaining to the reader how to use current argumentation methods and concepts that are increasingly being implemented in more precise ways for the application of software tools in computational argumentation systems. It shows how the use of these tools and methods requires a new approach to the concepts of knowledge and explanation suitable for diverse settings, such as issues of public safety and health, debate, legal argumentation, forensic evidence, science education, and the use of expert opinion evidence in personal and public deliberations.