Douglas Walton

(? - 2020)

There are two views of the ad hominem argument found in the textbooks and other traditional treatments of this argument, the Lockean or ex concessis view and the view of ad hominem as personal attack. This article addresses problems posed by this ambiguity. In particular, it discusses the problem of whether Aristotle's description of the ex concessis type of argument should count as evidence that he had identified the circumstantial ad hominem argument. Argumentation schemes are used as the basis for drawing a distinction between this latter form of argument and another called argument from commitment, corresponding to the ex concessis argument

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.

This article evaluates the strengths and weaknesses of arguments based on appeals to expertise. The intersection of two areas is explored: (i) the traditional argumentum ad verecundiam (literally, “appeal to modesty,” but characteristically the appeal to the authority of expert judgment) in informal logic, and (ii) the uses of expert systems in artificial intelligence. The article identifies a model of practical reasoning that underlies the logic of expert systems and the model of argument appropriate for the informal logic of the argumentum ad verecundiam

In this paper we show how dialogue-based theories of argumentation can contribute to the construction of effective systems of dispute resolution. Specifically we consider the role of persuasion in online dispute resolution by showing how persuasion dialogues can be functionally embedded in negotiation dialogues, and how negotiation dialogues can shift to persuasion dialogues. We conclude with some remarks on how persuasion dialogues might be modelled is such a way as to allow them to be implemented in a mechanical or computerized system of dialogue or dialogue management.

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.

This paper compares the features and methods of the two leading implemented systems that offer a tool for helping a user to find or invent arguments to support or attack a designated conclusion, the Carneades Argumentation System and the IBM Watson Debater tool. The central aim is to contribute to the understanding of scholars in informal logic, rhetoric and argumentation on how these two software systems can be useful for them. One contribution of the paper is to explain to these potential users how the two tools are applicable to the task of inventing arguments by using some simple illustrative examples. Another is to redefine the structure of argument invention as a procedure.

The aims of this paper are to survey, explicate, compare, contrast, and critically evaluate a number of (mainly recent and technical) contributions (Kanger, Porn and Áqvist) to the logic of action locutions in connection with their treatment of the concept of an agent's bringing about a state of affairs. The discussion is primarily concerned with practical applications of these formalisms for the action theorist. It is suggested that these systems are best understood as capturing a strategic sense of bringing-about, and not a notion of actual bringing-about, which is merely presupposed by them. It is argued that the developments surveyed open up a new 'intensional' style of action theory, contrasted with the 'extensional' approach of Davidson. Yet because of the treatment of conditionals, they fail to capture a basic notion of 'bringing about' important for action theory. It is concluded that a study of the behavior of 'bringing-about' over non-standard conditionals would be a useful next step for intensional action logic.

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. CAS 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, it is shown how formal dialectic can be extended to model multi-agent argumentation in which each participant is an agent. An agent is viewed as a participant in a dialogue who not only has goals, and the capability for actions, but who also has stable characteristics of types that can be relevant to an assessment of some of her arguments used in that dialogue. When agents engage in argumentation in dialogues, each agent has a credibility function that can be adjusted upwards or downwards by certain types of arguments brought forward by the other agent in the dialogue. One type is the argument against the person or argumentum ad hominem, in which personal attack on one party's character is used to attack his argument. Another is the appeal to expert opinion, traditionally associated with the informal fallacy called the argumentum ad verecundiam. In any particular case, an agent will begin a dialogue with a given degree of credibility, and what is here called the credibility function will affect the plausibility of the arguments put forward by that agent. In this paper, an agent is shown to have specific character traits that are vital to properly judging how this credibility function should affect the plausibility of her arguments, including veracity, prudence, sincerity and openness to opposed arguments. When one of these traits is a relevant basis for an adjustment in a credibility function, there is a shift to a subdialogue in which the argumentation in the case is re-evaluated. In such a case, it is shown how the outcome can legitimately be a reduction in the credibility rating of the arguer who was attacked. Then it is shown how the credibility function should be brought into an argument evaluation in the case, yielding the outcome that the argument is assigned a lower plausibility value.

The standard account of denying the antecedent (DA) is that it is a deductively invalid form of argument, and that, in a conditional argument, to argue from the falsity of the antecedent to the falsity of the consequent is always fallacious. In this paper, we argue that DA is not always a fallacious argumentative strategy. Instead, there is a legitimate usage of DA according to which it is a defeasible argument against the acceptability of a claim. The dialectical effect of denying the antecedent is to shift the burden of proof back to the original proponent of a claim. We provide a model of this non-fallacious usage which is built upon pragmatic models of argumentation

Hamblin distinguished between formal and descriptive dialectic. Formal normative models of deliberation dialogue have been strongly emphasized as argumentation frameworks in computer science. But making such models of deliberation applicable to real natural language examples has reached a point where the descriptive aspect needs more interdisciplinary work. The new formal and computational models of deliberation dialogue that are being built in computer science seem to be closely related to some already existing and very well established computing technologies such as problem solving and decision making, but whether or how dialectical argumentation can be helpful to support these systems remains an open question. The aim of this paper is to examine some real examples of argumentation that seem to hover on the borderlines between deliberation, problem solving and decision making.

In a critical study of some recent action theory Professor James Tomberlin [7] makes some insightful and suggestive remarks concerning the by now well known problem of "Smith and the airplane" formulated by Keith Lehrer and Richard Taylor [3]. While these remarks do significantly advance our knowledge of the nature of the problem, I would like to try to show why the strategy they indicate does not lead to a solution that represents any improvement on the one developed in [1], [8] and [2].The problem of Smith and the airplane is posed by the following apparent inconsistency. Suppose it is now shortly before 3:30 and Smith is at a country airport. The 3:30 plane is the only possible means whereby Smith can arrive at the city at 4:00. There is nothing to prevent Smith from leaving on the 3:30 plane, but he in fact does not do so: Then each of the following statements are true.

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.

G. H. R. Parkinson, The Renaissance and Seventeenth-century Rational-ism London and New York:Routledge, 1993. xxix + 444 pp. £55.00 J. Pafel, Subjekt, Prädikat, Objekt, Eine semantische Definition grammatischer Funktionen, Frankfurt am Main:Peter Lang, 1991. 166 pp Dieter Munch, Intention und Zeichen, Untersuchungen zu Franz Brentano und zu Edmund Husserls Frühwerk. Frankfurt am Main:Suhrkamp, 1993, v+324 pp. DM 42 J, Lameer, Al-Farabi & Aristotelian syllogistics:Greek theory & Islamic practice. Leiden: E, J. Brill, 1994. xx + 351 pp. Nig. 130.00/$74.50 F. H. Bradley, Writings on Logic and Metaphysics, edited by James W. Allard and Guy Stock, Oxford, Clarendon Press, 1994. xv and 357 pp. £40, £14.95 Christoph Kann, Die Eigenschaften der Termini:Eine Untersuchung zur Per-uulis Logica Alberts von Sachsen, Leiden, New York, Köln: Brill, 1994. 267 pp. Hfl. 120 $68.7 Robert C. Solomon and Kathleen M. Higgins, The age of German Idealism.. 1994, London and New York:Routledge, xxv + 408 pp. £55.00 K. Dorter, Form and Good in Plato's Eleatic Dialogues, Berkeley:University of California Press, 1994. x + 256pp. $45.00 Stephen Read, Thinking about logic:an introduction to the philosophy of logic, Oxford: Oxford University Press, 1995. vii + 262 pp. £8.99 G. Boolos, The logic of provability. Cambridge, New York, and Melbourne:Cambridge University Press, 1993. xxxvi + 276 pp. $59.95 Kathleen Johnson Wu, Discovering formal logic. Guilford, Connecticut:The Dushkin Publishing Group, Inc., 1994. xxiv + 529 pp. $32.95 Kevin L. Flannery, S. J., Ways into the logic of Alexander of Aphrodisias, Leiden:E. J. Brill, 1995. xxiv + 170 pp José Ferreirós Domínguez, El Nacimiento de la Teoria de Conjuntos, 1854-1908. Madrid:Universidad Autönoma, 1993, 394 pp. No price stated Nathalie Charraud, Infini et inconscient. Essai sur Georg Cantor. Paris:Anthropos, 1994. 299 pp. 190F John G. Slater, Bertrand Russell. Bristol, U.K.:Thoemmes Press, 1994. xii + 171 pp. No price stated Stefan Andersson In quest of certainty, Bertand Russell's search for certainty in religion and mathematics up to "The principles of mathematics", Stockholm:Almqvist and Wilksell International, 1994. xiii + 192 pp. No price stated Karl Menger, Reminiscences of the Vienna Circle and the Mathematical Colloquium, Edited by Louise Golland, Brian McGuinness and Abe Sklar. Dordrecht, Boston and London:Kluwer Academic Publishers, 1994. xxvi + 244 pp. No price stated Sun-Joo Shin, The Logical Status of Diagrams. Cambridge, UK, and New York:Cambridge University Press, 1994. xi + 197 pp. $39.95

In this paper some lessons are learned regarding how to extend and deepen the theory of Macagno on assessing dialectical relevance by using the notion of argument distance. An argument is defined as dialectically relevant if it is an appropriate move in a multiagent dialogue exchange. Three examples are studied where a criticism of relevance is made against an argument, and the problem posed is how a response to this type of criticism should be judged to be justified or not, based on the evidence. Based on these examples, an algorithm is presented that helps the user to determine argument distance in a given case as a means of helping to judge whether a criticism that an argument is not relevant is justified or not.

This paper begins with a brief account of how I started out as a young logician studying modal logic with the hope that it would be useful when applied to evaluating real examples of arguments found in natural language texts. The exposition moves on to relate how my interests shifted to the study of argumentation in informal logic, and from there to computational systems combining defeasible argumentation schemes with argument mapping (diagramming). The story ends by leading to recent collaborations with three young logicians and computer scientists who are continuing on the path of my journey.

This book provides an argumentation model for means-end reasoning, a distinctive type of reasoning used for problem-solving gand decision-making. Means-end reasoning is modeled as goal-directed argumentation from an agent's goals and known circumstances, and from an action selected as a means, to a decision to carry out the action. Goal-based reasoning for argumentation provides an argumentation model for this kind of reasoning, showing how it is employed in settings of intelligent deliberation where agents try to collectively arrive at a conclusion on what they should do to move forward in a set of circumstances. The book explains how this argumentation model can help build more realistic computational systems of deliberation and decision-making and shows how such systems can be applied to solve problems posed by goal-based reasoning in numerous fields, from social psychology and sociology, to law, political science, anthropology, cognitive science, artificial intelligence, multi-agent systems, and robotics." -- Back cover.

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.