Douglas Walton

(? - 2020)

This paper offers a solution to the problem of understanding how a fallacious argument can be deceptive by “seeming to be valid”, or (better) appearing to be a better argument of its kind than it really is. The explanation of how fallacies are deceptive is based on heuristics and paraschemes. Heuristics are fast and frugal shortcuts to a solution to a problem that sometimes jump to a conclusion that is not justified. In fallacious instances, according to the theory proposed, this jump overlooks prerequisites of the defeasible argumentation scheme for the type of argument in question. Three informal fallacies, argumentum ad verecundiam , argumentum ad ignorantiam and fear appeal argument, are used to illustrate and explain the theory

The appeal to pity, orargumentum ad misericordiam, has traditionally been classified by the logic textbooks as an informal fallacy. The particular case studied in this article is a description of a series of events in 1990–91 during the occupation of Kuwait by Iraqi forces. A fifteen-year-old Kuwaiti girl named Nayirah had a pivotal effect on the U.S. decision to invade Kuwait by testifying to a senate committee (while crying) that Iraqi soldiers had pulled babies out of incubators in a hospital in Kuwait, and left them to die. Subsequent investigations revealed no basis for this claim, and that it was part of a public relations campaign, financed mainly by Kuwaitis, to get support for the invasion. The normative question studied in this case is whether or not the argument in it can correctly be evaluated as a fallacious appeal to pity. Part of the general issue is what is meant by the key word ‘fallacious.’

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

The traditional fallacy of many questions, also known as the fallacy of complex question, illustrated by the question, "Have you stopped sexually harassing your students?", has been known since ancient times, but is still alive and well. What is of practical importance about this fallacy is that it represents a tactic of entrapment that is very common in everyday argumentation, as well as in special kinds of argumentation like that in a legal trial or a parliamentary debate. The tactic combines the use of loaded questions with the complexity of the question. A key notion is that of the presupposition of the question. How to deal with such questions is a point of departure for interrogative theory, and for any attempts to construct formal dialogues of a kind that can be used as normative models of argumentation

Current practice in logic increasingly accords recognition to abductive, presumptive or plausible arguments, in addition to deductive and inductive arguments. But there is uncertainty about what these terms exactly mean, what the differences between them are (if any), and how they relate. By examining some analyses ofthese terms and some of the history of the subject (including the views of Peirce and Cameades), this paper sets out considerations leading to a set of definitions, discusses the relationship of these three forms of argument to argumentation schemes and sets out a new argumentation scheme for abductive argument

It is unfortunate that Hamblin’s contributions do not get him the credit he deserves for his remarkable achievements. Although his contributions to philosophy are well enough recognized, and his early contributions to computing have been acknowledged, it seems strange that his work has not been widely enough recognized for the interdisciplinary effect it has had. There has been a feedback loop whereby his theories on formal dialogue systems and imperatives were taken up in argumentation, applied in computing, and then used in this form to refine argumentation methods

In this paper, it is shown (1) that there are two schemes for argument from analogy that seem to be competitors but are not, (2) how one of them is based on a distinctive type of similarity premise, (3) how to analyze the notion of similarity using story schemes illustrated by some cases, (4) how arguments from precedent are based on arguments from analogy, and in many instances arguments from classification, and (5) that when similarity is defined by means of episode schemes, we can get a clearer idea of how it integrates with the use of argument from classification and argument from precedent in case-based reasoning by using a dialogue structure

It is shown how two defeasible forms of argument, argument from appearance and abductive reasoning, are central tools of artificial intelligence for the analysis and evaluation of legal evidence. Defeasible argumentation schemes representing these forms of argument are presented, and applied to examples of the kind of reasoning used to draw a conclusion by inference from observational data. A common example from the Greek philosopher Carneades, the ancient case of the snake and the rope, is used to show how inferences from an appearance to a conclusion about the contents of that appearance are fallible, but can be provisionally acceptable. It is argued that the lessons of this example have not been fully taken advantage of in modern theories of reasoning, and that the best way to come to apply them is to use argumentation tools like argumentation schemes and argument diagramming. © 2011 Elsevier B.V., All rights reserved.