Recent proposals for computer-assisted argumentation have drawn on dialectical models of argumentation. When used to assist public policy planning, such systems also raise questions of political legitimacy. Drawing on deliberative democratic theory, we elaborate normative criteria for deliberative legitimacy and illustrate their use for assessing two argumentation systems. Full assessment of such systems requires experiments in which system designers draw on expertise from the social sciences and enter into the policy deliberation itself at the level of participants.

Arguers sometimes cite a decision made in an earlier situation as a reason for making the equivalent decision in a later situation. I argue that there are two kinds of “case-to-case arguments”. First, there are arguments by precedent, which cite the mere existence of the past decision as a reason to decide in the same way again now, independent of the past decision’s merits. Second, there are case-to-case arguments from parralel reasoning which presuppose that the past decision was justified and (...) are used to show that an equivalent present decision would also be justified. Both arguments are a type of argument by analogy. They differ in their structures and conditions of cogency, even though they often look the same in presentation. Their similar appearance poses a risk of miss-evaluation and fallacious use. Therefore a clearly theorized distinction is important. (shrink)

If arguments are to generate public knowledge, as in the sciences, then they must travel, finding acceptance across a range of local contexts. But not all good arguments travel, whereas some bad arguments do. Under what conditions may we regard the capacity of an argument to travel as a sign of its cogency or public merits? This question is especially interesting for a contextualist approach that wants to remain critically robust: if standards of cogency are bound to local contexts of (...) evaluation, then how may arguments legitimately travel at all? The key to a contextualist conception of cogent travel, I argue, lies in the way local contexts are linked to broader contexts of evaluation by relations of relevance. The burden of the article is to elaborate the different forms these relations can take in the travel of scientific arguments. (shrink)

A conclusion follows from given premisses if and only if an acceptable counterfactual-supporting covering generalization of the argument rules out, either definitively or with some modal qualification, simultaneous acceptability of the premisses and non-accepta-bility of the conclusion, even though it does not rule out acceptability of the premisses and does not require acceptability of the conclusion independently of the premisses. Hence the reiterative associated conditional of an argument is true if and only it has such a covering generalization, and a (...) supposed unexpressed premiss supplied to make an argument formally valid should be a covering generalization. (shrink)

This paper reports our research concerning dialogue strategies suitable for adoption by a human-computer debating system. We propose a set of strategic heuristics for a computer to adopt to enable it to function as a dialogue participant. In particular, we consider means of assessing the proposed strategy. A system involving two agents in dialogue with each other and a human-agent debate system are constructed and subsequently used to facilitate the evaluations. The evaluations suggest that the proposed strategy can enable the (...) computer to act as an effective dialogue participant. It is anticipated that this work will contribute towards the development of computerised dialogue systems and help to illuminate research issues concerning strategies in dialectical systems. (shrink)

Agents require a constant flow, and a high level of processing, of relevant semantic information, in order to interact successfully among themselves and with the environment in which they are embedded. Standard theories of information, however, are silent on the nature of epistemic relevance. In this paper, a subjectivist interpretation of epistemic relevance is developed and defended. It is based on a counterfactual and metatheoretical analysis of the degree of relevance of some semantic information i to an informee/agent a, as (...) a function of the accuracy of i understood as an answer to a query q, given the probability that q might be asked by a. This interpretation of epistemic relevance vindicates a strongly semantic theory of information, according to which semantic information encapsulates truth. It accounts satisfactorily for several important applications and interpretations of the concept of relevant information in a variety of philosophical areas. And it interfaces successfully with current philosophical interpretations of causal and logical relevance. (shrink)

The lack of a theory of relevance in the current state of the art of informal logic has often been considered regrettable, a gap that must be filled before the Relevance-Sufficiency-Acceptability model can be considered complete. I wish to challenge this view. A theory of relevance is neither desirable nor possible. Informal logic can get by perfectly well, and has been doing so far, with relevance judgments that are by nature unanalysable and intuitive. Criticism of theories of relevance, for example (...) in Woods , is deflated. (shrink)

In this overview article, we first explain what we take informal logic to be, discussing misconceptions and distinguishing our conception of it from competing ones; second, we briefly catalogue recent informal logic research, under 14 headings; third, we suggest four broad areas of problems and questions for future research; fourth, we describe current scholarly resources for informal logic; fifth, we discuss three implications of informal logic for philosophy in particular, and take note ofpractical consequences of a more general sort.

I argue, contrary to a recent assertion by Lilian Bermejo-Luque, that the inference-claim in an argument of the form ‘p, so q’ is not its associated material conditional ‘if p then q’. Rather, it is the claim that the argument has a covering generalization that is non-trivially true. I defend this interpretation against three objections by Bermejo-Luque.

Appeals to authority have a long tradition in the history of argumentation theory. During the Middle Age they were considered legitimate and sound arguments, but after Locke’s treatment in the Essay Concerning Human Understanding their legitimacy has come under question. Traditionally, arguments from authority were considered informal arguments, but since the important work of Charles Hamblin many attempts to provide a form for them have been done. The most convincing of them is the presumptive form developed by Douglas Walton and (...) John Woods that aims at taking into account the relevant contextual aspects in assessing the provisional validity of an appeal to authority. The soundness of an appeal depends on its meeting the adequacy conditions set to scrutinize all the relevant questions. I want to claim that this approach is compatible with the analysis of arguments in terms of relevance advanced by David Hitchcock. He claims that relevance is a triadic relation between two items and a context. The first item is relevant to the second one in a given context. Different types of relevance relation exist, namely causal relevance and epistemic relevance. “Something is [causally] relevant to an outcome in a given situation if it helps to cause that outcome in the situation”, whereas it is epistemically relevant when it helps to achieve an epistemic goal in a given situation. I claim that we can adapt this conception to Walton and Krabbe’s theory of dialogue type, seeing the items of a relevance relation as the argument and its consequence and the context as the type of dialogue in which these arguments are advanced. According to this perspective, an argument from authority that meets the adequacy conditions has to be considered legitimate because it is an epistemically relevant relation. Therefore, my conclusion is that an analysis of appeals to authority in terms of relevance can be a useful tool to establish fallaciousness or legitimacy of such a kind of argument even within the established paradigm of argumentation theory. (shrink)

My project is a systematic inquiry into the problem of relevance, which has been identified as an enduring difficulty in, for example, informal logic and information science where it plays a fundamental role in argument and information searches, respectively. My first task involves determining exactly what the problem of relevance is. To achieve that, I collected problem statements from the literature but I also analysed literature on relevance to discover further problems. The key problem that I investigate concerns the question, (...) 'What is relevance?', which I take to concern the meaning and occurrence of relevance. Concerning the semantic question, I suggest that it demarcates a point of time prior to asking it. Subsequently, I identified and evaluated approaches to elucidating the notion of relevance, rejected intuitionism and stipulation as suitable approaches, and selected philosopher/physicist Mario Bunge's approach to scientific philosophy and his conceptual system to frame my study. I also assess potential information sources; rejected constructed examples that prove to be contrived or are used to illustrate a stipulated definition; and selected dictionary definitions, actual statements, and carefully constructed examples as information sources to complement my review of the literature on relevance. To elucidate relevance, I traced the concept back to its Greek roots, analysed statements, and concluded that the term 'relevance' since its inception in Scottish law in the early 1500's has been limited largely to relations of significance. Understanding relevance in terms of both connection and significance is crucial to construct, identify, or evaluate relevance statements and thereby develop a representative theory of relevance. It also provides a solution to many controversies such as degree of relevance and it helps elucidate notions such as strength and sufficiency of an argument. I suggest that as significance can vary in degree, so too can relevance but a connection between objects is presupposed in both cases. Strength is a measure of significance and sufficiency is the strength required to establish a conclusion. Finally, I offer a provisional and partial theory of relevance where I summarize my prior analyses and integrate/comment on published positions on relevance. (shrink)

I characterize the deductivist ideal of justification and, following to a great extent Toulmin’s work The Uses of Argument, I try to explain why this ideal is erroneous. Then I offer an alternative model of justification capable of making our claims to knowledge about substantial matters sound and reasonable. This model of justification will be based on a conception of justification as the result of good argumentation, and on a model of argumentation which is a pragmatic linguistic reconstruction of Toulmin’s (...) model of argument. (shrink)

This paper presents the concept of relevance in argumentation theory analyzed from a pragma-rhetorical angle. Special attention will be given to examples in which relevance is determined by the extended social context of the use of presentational devices in controversies. The analysis of examples will include the rhetorical concept of decorum, maintaining that a different emphasis should be given to the role of the speaker in the determination of relevance.