Douglas Walton

(? - 2020)

In this paper a theoretical definition that helps to explain how the logical structure of legal presumptions is constructed by applying the Carneades model of argumentation developed in artificial intelligence. Using this model, it is shown how presumptions work as devices used in evidentiary reasoning in law in the event of a lack of evidence to assist a chain of reasoning to move forward to prove or disprove a claim. It is shown how presumptions work as practical devices that may be useful in cases in which there is insufficient evidence to prove the claim to an appropriate standard of proof

Fallacies of relevance, a major category of informal fallacies, include two that could be called pure fallacies of relevance-the wrong conclusion fallacy and the red herring digression, diversion) fallacy. The problem is how to classify examples of these fallacies so that they clearly fall into the one category or the other, on some rational system of classification. In this paper, the argument diagramming software system, Araucaria. is used to analyze the argumentation in some selected textbook examples of pure fallacies of relevance. A system of classification of these fallacies is proposed, and criteria for determining whether an example should be classified as wrong conclusion or red herring are formulated. A key difference cited is that in a case where the red herring fallacy has been committed, even if the argument may go to a wrong conclusion, there is evidence of the use ofa deceptive tactic of diversion. Textual evidence must indicate that the arguer deliberately interjects a distracting controversy to lead the respondent away from the real issue to be disputed.

The purpose of this paper is to analyze the structure and the defeasibility conditions of argument from analogy, addressing the issues of determining the nature of the comparison underlying the analogy and the types of inferences justifying the conclusion. In the dialectical tradition, different forms of similarity were distinguished and related to the possible inferences that can be drawn from them. The kinds of similarity can be divided into four categories, depending on whether they represent fundamental semantic features of the terms of the comparison or non-semantic ones, indicating possible characteristics of the referents. Such distinct types of similarity characterize different kinds of analogical arguments, all based on a similar general structure, in which a common genus is abstracted. Depending on the nature of the abstracted common feature, different rules of inference will apply, guaranteeing the attribution of the analogical predicate to the genus and to the primary subject. This analysis of similarity and the relationship thereof with the rules of inference allows a deeper investigation of the defeasibility conditions.

This article analyses the fallacy of wrenching from context, using the dialectical notions of commitment and implicature as tools. The data, a set of key examples, is used to sharpen the conceptual borderlines around the related fallacies of straw man, accent, misquotation, and neglect of qualifications. According to the analysis, the main characteristics of wrenching from context are the manipulation of the meaning of the other’s statement through devices such as the use of misquotations, selective quotations, and quoting out of context. The theoretical tools employed in the analysis are pragmatic theories of meaning and a dialectical model of commitment, used to explain how and why a standpoint is distorted. The analysis is based on a conception of fallacies as deceptive strategic moves in a game of dialogue. As a consequence, our focus is not only on misquotations as distortions of meaning, but on how they are used as dialectical tools to attack an opponent or win a dispute. Wrenching from context is described as a fallacy of unfairly attributing a commitment to another party that he never held. Its power as a deceptive argumentation tactic is based on complex mechanisms of implicit commitments and on their misemployment to improperly suggest an attribution of commitment

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

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.

Using tools like argument diagrams and profiles of dialogue, this paper studies a number of examples of everyday conversational argumentation where determination of relevance and irrelevance can be assisted by means of adopting a new dialectical approach. According to the new dialectical theory, dialogue types are normative frameworks with specific goals and rules that can be applied to conversational argumentation. In this paper is shown how such dialectical models of reasonable argumentation can be applied to a determination of whether an argument in a specific case is relevant are not in these examples. The approach is based on a linguistic account of dialogue and text from congruity theory, and on the notion of a dialectical shift. Such a shift occurs where an argument starts out as fitting into one type of dialogue, but then it only continues to makes sense as a coherent argument if it is taken to be a part of a different type of dialogue

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

This paper applies recent work on scripts and stories developed as tools of evidential reasoning in artificial intelligence to model the use of argument from analogy as a rhetorical device of persuasion. The example studied is Gerry Spence’s closing argument in the case of Silkwood v. Kerr-McGee Corporation, said to be the most persuasive closing argument ever used in an American trial. It is shown using this example how argument from analogy is based on a similarity premise where similarity between two cases is modeled using the device of a story scheme from the hybrid theory of legal evidential reasoning (Bex in Arguments, stories and criminal evidence: a formal hybrid theory. Springer, Dordrecht 2011). It is shown how the rhetorical strategy of Spence’s argumentation in the closing argument interweaves argument from analogy with explanation through three levels

In this paper we analyze the uses and misuses of argumentation schemes from verbal classification, and show how argument from definition supports argumentation based on argument from verbal classification. The inquiry has inevitably included the broader study of the concept of definition. The paper presents the schemes for argument from classification and for argument from definition, and shows how the latter type of argument so typically supports the former. The problem of analyzing arguments based on classification is framed in a structure that reveals the crucial role it plays in the persuasion process. The survey of the literature includes the work of Hastings, Perelman, Kienpointner and Schiappa, but still finds much of value in Aristotle. Lessons drawn from Aristotle’s Topics are shown to be useful for developing new tools for assessing definitions and arguments from definition

Tribunals have come to depend increasingly on expertise for determining the facts in cases. However, current legal methods have proved problematic to work with. This paper argues that, as a special model of public understanding of science, assessing expertise should consider source credibility of expertise from internal aspects, including scientific validity and reliability, and external aspects involving the credibility of experts. Using the Carneades Argumentation System we show that the internal and the external aspects are mediated by the structure of the argument from expert opinion with its matching set of critical questions

We contend that it is possible to argue reasonably for and against arguments from classifications and definitions, provided they are seen as defeasible (subject to exceptions and critical questioning). Arguments from classification of the most common sorts are shown to be based on defeasible reasoning of various kinds represented by patterns of logical reasoning called defeasible argumentation schemes. We show how such schemes can be identified with heuristics, or short-cut solutions to a problem. We examine a variety of arguments of this sort, including argument from abductive classification, argument from causal classification, argument from analogy-based classification and arguments from classification based on generalizations

Five errors that fit under the category of jumping to a conclusion are identified: (1) arguing from premises that are insufficient as evidence to prove a conclusion (2) fallacious argument from ignorance, (3) arguing to a wrong conclusion, (4) using defeasible reasoning without being open to exceptions, and (5) overlooking/suppressing evidence. It is shown that jumping to a conclusion is best seen not as a fallacy itself, but as a more general category of faulty argumentation pattern underlying these errors and some related fallacies

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.

The concept of a witch hunt is frequently invoked, in recent times, to describe a kind of procedure for deciding the guilt of a person against whom an accusation has been made. But what exactly is a witch hunt? In this paper, ten conditions are formulated as a cluster of properties characterizing the witch hunt as a framework in which arguments are used: (1) pressure of social forces, (2) stigmatization, (3) climate of fear, (4) resemblance to a fair trial, (5) use of simulated evidence, (6) simulated expert testimony, (7) nonfalsifiability characteristic of evidence, (8) reversal of polarity, (9) non-openness, and (10) use of the loaded question technique. The witch hunt, as characterized by these criteria, is shown to function as a negative normative structure for evaluating argumentation used in particular cases

This article concerns the structure of defeasible arguments like: 'If Bob has red spots, Bob has the measles; Bob has red spots; therefore Bob has the measles.' The issue is whether such arguments have the form of modus ponens or not. Either way there is a problem. If they don't have the form of modus ponens, the common opinion to the contrary taught in leading logic textbooks is wrong. But if they do have the form of modus ponens, doubts are raised about the conventional dogma that all arguments having the form of modus ponens are deductively valid. By carefully examining arguments on both sides of the issue, reasonable doubts are raised about the view that all arguments having a modus ponens form are valid

What are the historical origins of the argumentum ad consequentiam, the argument from consequences, sometimes featured as an informal fallacy in logic textbooks? As shown in this paper, knowledge of the argument can be traced back to Aristotle. And this type of argument shows a spotty history of recognition in logic texts and manuals over the centuries. But how it got into the modern logic textbooks as a fallacy remains somewhat obscure. Its modern genesis is traced to the logic text of James McCosh

Although studies have yielded a detailed taxonomy of types of slippery slope arguments, they have failed to identify a basic argumentation scheme that applies to all. Therefore, there is no way of telling whether a given argument is a slippery slope argument or not. This paper solves the problem by providing a basic argumentation scheme. The scheme is shown to fit a clear and easily comprehensible example of a slippery slope argument that strongly appears to be reasonable, something that has also been lacking.

Essential to an understanding of argumentation and logic, Ad Hominem Arguments is a vital contribution to legal theory and media and civic discourse. In the 1860s, northern newspapers attacked Abraham 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, or personal attack argument, has now been carefully refined as an instrument of "oppo tactics" and "going negative" by the public relations experts who craft political campaigns at the national level. In this definitive treatment of one of the most important concepts in argumentation theory and informal logic, Douglas Walton presents a normative framework for identifying and evaluating ad hominem or personal attack arguments. Personal attack arguments have often proved to be so effective, in election campaigns, for example, that even while condemning them, politicians have not stopped using them. In the media, in the courtroom, and in everyday confrontation, ad hominem arguments are easy to put forward as accusations, are difficult to refute, and often have an extremely powerful effect on persuading an audience. Walton gives a clear method for analyzing and evaluating cases of ad hominem arguments found in everyday argumentation. His analysis classifies the ad hominem argument into five clearly defined subtypes-abusive (direct), circumstantial, bias, "poisoning the well," and tu quoque ("you're just as bad") arguments-and gives methods for evaluating each type. Each subtype is given a well-defined form as a recognizable type of argument. 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 argumentation as fallacious or not in particular cases.

How should we evaluate an argument in which two witnesses independently testify to some claim? In fact what would happen is that the testimony of the second witness would be taken to corroborate that of the first to some extent, thereby boosting up the plausibility of the first argument from testimony. But does that commit the fallacy of double counting, because the second testimony is already taken as independent evidence supporting the claim? Perhaps the corroboration effect should be considered illogical, since each premise should be seen as representing a separate reason in a convergent argument for accepting the claim as plausible. In this paper, we tackle the problem using argumentation schemes and argument diagramming. We examine a number of examples, and come up with two hypotheses that offer methods of analyzing and evaluating this kind of evidence

The importance of speech acts for analyzing and evaluating argumentation in cases where it is suspected that the ad baculum fallacy has been committed is demonstrated in this paper by using a typical textbook example of this fallacy. It is shown how the argument in the example can be analyzed and evaluated using the devices of Gricean implicature and indirect speech acts. It is shown how these two devices can be applied to extrapolate the evidence furnished by the text and dialectical context of the example

This paper applies dialectical argumentation structures to the problem of analyzing the ad baculum fallacy. It is shown how it is necessary in order to evaluate a suspected instance of the this fallacy to proceed through three levels of analysis: an inferential level, represented by an argument diagram, a speech act level, where conditions for specific types of speech acts are defined and applied, and a dialectical level where the first two levels are linked together and fitted into formal dialogue structures. The paper adds a new type of dialogue called advising dialogue that needs to be applied at the third level.

In this paper it is shown is that although poisoning the well has generally been treated as a species of ad hominem fallacy, when you try to analyze the fallacy using ad hominem schemes, even by supplementing with related schemes like argument from position to know, the analysis ultimately fails. The main argument of the paper is taken up with proving this negative claim by applying these schemes to examples of arguments associated with the fallacy of poisoning the well. Although there is a positive finding in this quest, in that poisoning the well is shown to be based on and associated with these forms of argument in interesting ways, the paper in the end is led to the conclusion that the fallacy is irreducibly dialectical. Poisoning the well is thus analyzed as a tactic to silence an opponent violating her right to put forward arguments on an issue both parties have agreed to discuss at the confrontation stage of a critical discussion. It is concluded that it is a special form of strategic attack used by one party in the argumentation stage of a critical discussion to improperly shut down the capability of the other party for putting forward arguments of the kind needed to properly move the discussion forward