Douglas Walton

(? - 2020)

This paper is a report of a pilot study of how candidates argue when they are running for political office. The election studied was the provincial election in Ontario, Canada, in the fall of 2011. Having collected about 250 arguments given during the election from newspaper media, we sought answers to the following questions, among others: which argumentation schemes have the greatest currency in political elections? Is a list of the best known argumentation schemes sufficient to classify the arguments given in elections? What schemes should be added to the familiar list to make it more adequate for studying elections? Is it useful to classify arguments as being used for positive, policy-critical, person-critical and defensive purposes? Can political parties be usefully characterized by noting their preferred kinds of arguments and their most frequent uses of arguments? What lessons can be learned from this study to better design future studies of the same kind?

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 paper presents a formalization of informal logic using the Carneades Argumentation System, a formal, computational model of argument that consists of a formal model of argument graphs and audiences. Conflicts between pro and con arguments are resolved using proof standards, such as preponderance of the evidence. Carneades also formalizes argumentation schemes. Schemes can be used to check whether a given argument instantiates the types of argument deemed normatively appropriate for the type of dialogue.

In this paper, a case study is conducted to test the capability of the Carneades Argumentation System to model the argumentation in a case where forensic evidence was collected in an investigation triggered by a conflict among art experts on the attribution of a painting to Leonardo da Vinci. A claim that a portrait of a young woman in a Renaissance dress could be attributed to da Vinci was initially dismissed by art experts. Forensic investigations were carried out, and evidence was collected by art history experts and scientific experts. The expert opinions were initially in conflict, but new evidence shifted the burden of proof onto the side of the skeptics. This paper presents an analysis of the structure of the interlocking argumentation in the case using argument mapping tools to track the accumulation of evidence pro and con

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

This paper presents an analysis of argumentation in direct-to-consumer health product ads in Newsweek that brings out special features of the arguments used in the ads, including practical reasoning, chained arguments, enthymemes, and prolepsis. A way to help overcome deficiencies in techniques of tailored health communication in consumer health informatics is shown by using argumentation schemes, argument visualisation tools, and dialogue models to frame these persuasive communication messages. The evidence collected is shown to be useful to allow the health informatics communicator and the person to whom message was directed to interact in a dialogue format where arguments can be put forward by both parties in a way that responds to the previous arguments and questions of the other party

In some recent cases in Anglo-American law juries ruled contrary to an expert's testimony even though that testimony was never challenged, contradicted or questioned in the trial. These cases are shown to raise some theoretical questions about formal dialogue systems in computational dialectical systems for legal argumentation of the kind recently surveyed by Bench-Capon (1997) and Hage (2000) in this journal. In such systems, there is a burden of proof, meaning that if the respondent questions an argument, the proponent is obliged to offer some support for it give it up. But what should happen in a formal system of dialogue if the proponent puts forward an argument and the respondent fails to critically question it, and simply moves on to another issue? Is this some kind of fault that should have implications? Should it be taken to imply that, by default, the respondent has conceded the argument? What, if anything, should be the outcome of such a failure to question in a formal dialogue system of argumentation? These questions are considered by examining some legal cases of expert opinion testimony in relation rules for formal dialectical argumentation systems.

This paper combines three computational argumentation systems to model the sequence of argumentation in a famous murder trial and the appeal procedure that followed. The paper shows how the argumentation scheme for argument from expert opinion can be built into a testing procedure whereby an argument graph is used to interpret, analyze and evaluate evidence-based natural language argumentation of the kind found in a trial. It is shown how a computational argumentation system can do this by combining argument schemes with argumentation graphs. Frighteningly, it is also shown by this example that when there are potentially confusing conflicting arguments from expert opinion, a jury can only too easily accept a conclusion prematurely before considering critical questions that need to be asked.

We present a high-level declarative programming language for representing argumentation schemes, where schemes represented in this language can be easily validated by domain experts, including developers of argumentation schemes in informal logic and philosophy, and serve as executable specifications for automatically constructing arguments, when applied to a set of assumptions. This new rule language for representing argumentation schemes is validated by using it to represent twenty representative argumentation schemes.

In this paper it is shown how plausible reasoning of the kind illustrated in the ancient Greek example of the weak and strong man can be analyzed and evaluated using a procedure in which the pro evidence is weighed against the con evidence using formal, computational argumentation tools. It is shown by means of this famous example how plausible reasoning is based on an audience’s recognition of situations of a type they are familiar with as normal and comprehensible in their shared common knowledge. The paper extends previous work on this example by using three new multiagent argumentation schemes closely related to the scheme for argument from negative consequences.

This paper combines methods of argumentation theory and artificial intelligence to extend existing work on the dialectical structure of crossexamination. The existing method used conflict diagrams to search for inconsistent statements in the testimony of a witness. This paper extends the method by using the inconsistency of commitments to draw an inference by the ad hominem argumentation scheme to the conclusion that the testimony is unreliable because of the bad ethical character for veracity of the witness.

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.

The notion of burden of proof and its companion notion of presumption are central to argumentation studies. This book argues that we can learn a lot from how the courts have developed procedures over the years for allocating and reasoning with presumptions and burdens of proof, and from how artificial intelligence has built precise formal and computational systems to represent this kind of reasoning. The book provides a model of reasoning with burden of proof and presumption, based on analyses of many clearly explained legal and non-legal examples. The model is shown to fit cases of everyday conversational argumentation as well as argumentation in legal cases. Burden of proof determines under what conditions an arguer is obliged to support a claim with an argument that backs it up and how strong that argument needs to be to prove the claim in question.

In this paper we show that an essential aspect of solving the problem of uncritical acceptance of expert opinions that is at the root of the ad verecundiam fallacy is the need to disentangle argument from expert opinion from another kind of appeal to authority. Formal and computational argumentation systems enable us to analyze the fault in which an error has occurred by virtue of a failure to meet one or more of the requirements of the argumentation scheme from argument from expert opinion. We present a method for enhancing this capability by showing how arguments from expert opinion are related to, but different from, arguments from deontic authority.

. A heuristic search procedure for inventing legal arguments is built on two tools already widely in use in argumentation. Argumentation schemes are forms of argument representing premise‐conclusion and inference structures of common types of arguments. Schemes especially useful in law represent defeasible arguments, like argument from expert opinion. Argument diagramming is a visualization tool used to display a chain of connected arguments linked together. One such tool, Araucaria, available free at , helps a user display an argument on the computer screen as an inverted tree structure with an ultimate conclusion as the root of the tree. These argumentation tools are applicable to analyzing a mass of evidence in a case at trial, in a manner already known in law using heuristic methods and Wigmore diagrams . In this paper it is shown how they can be automated and applied to the task of inventing legal arguments. One important application is to proof construction in trial preparation