The informal logic movement began as an attempt to develop – and teach – an alternative logic which can account for the real life arguing that surrounds us in our daily lives – in newspapers and the popular media, political and social commentary, advertising, and interpersonal exchange. The movement was rooted in research and discussion in Canada and especially at the University of Windsor, and has become a branch of argumentation theory which intersects with related traditions and approaches (notably formal (...) logic, rhetoric and dialectics in the form of pragma-dialectics). In this volume, some of the best known contributors to the movement discuss their views and the reasoning and argument which is informal logic’s subject matter. Many themes and issues are explored in a way that will fuel the continued evolution of the field. Federico Puppo adds an insightful essay which considers the origins and development of informal logic and whether informal logicians are properly described as a “school” of thought. In considering that proposition, Puppo introduces readers to a diverse range of essays, some of them previously published, others written specifically for this volume. (shrink)

Blair articulates a concept of argument that suggests, as he puts it, that argument is a normative concept (Blair, Informal Logic 24:137–151, 2004, p. 190). Put roughly, the idea is that a collection of propositions doesn’t constitute an argument unless some taken together constitute a reason for the remaining proposition and thereby support it enough to provide at least prima facie justification for it (Blair, in: Blair, Johnson, Hansen, Tindale (eds) Informal Logic at 25, Proceedings of the 25th anniversary conference, (...) Ontario Society for the Study of Argumentation, 2003, p.173). My primary task in this paper is to advance an understanding of the illative unit of argument and the reasons associated with it that provides an intuition pump for a normative concept of argument. My aim is to advance a positive consideration in favor of a normative concept of argument that motivates its further development. I take the normative concept of argument I defend here to be in the same ballpark as the one Blair characterizes. (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)

I show that in our theoretical representations of argument, vicious infinite regresses of self-reference may arise with respect to each of the three usual, informal criteria of argument cogency: the premises are to be relevant, sufficient, and acceptable. They arise needlessly, by confusing a cogency criterion with argument content. The three types of regress all are structurally similar to Lewis Carroll’s famous regress, which involves quantitative extravagance with no explanatory power. Most attention is devoted to the sufficiency criterion, including its (...) relation to the view au courant that inferring necessarily involves the thinker taking her premises to support her conclusion. I contend that this view is mistaken and likewise that arguments make no such assumption or inference claim as that the premises support the conclusion. The core of the positive alternative model I propose is that there is commitment to, but not claiming, the proposition that the premises support the conclusion. (shrink)

When a speaker states an argument in arguing—in its core sense—for the conclusion, the speaker asserts, as opposed to merely implies or implicates, the associated inference claim to the effect that the conclusion follows from the premises. In defense of this, I argue that how an inference claim is conveyed when stating an argument is constrained by constitutive and normative conditions for core cases of the speech of arguing for a conclusion. The speech act of assertion better reflects such conditions (...) than does implication, conversational implicature, or conventional implicature. (shrink)

Arguments figure prominently in our practices of reason-giving. For example, we use them to advance reasons for their conclusions in order to justify believing something, to explain why we believe something, and to persuade others to believe something. Intuitively, using arguments in these ways requires a certain degree of self-reflection. In this paper, I ask: what cognitive requirements are there for using an argument to advance reasons for its conclusion? Towards a partial response, the paper’s central thesis is that in (...) order to so use an argument one must believe the associated inference claim to the effect that the premises collectively are reasons that support the conclusion. I then argue against making it a further cognitive requirement that one be aware of one’s justification for believing such an inference claim. This thesis provides a rationale for the typical informal-logic textbook characterization of argument and motivates a constraint on adequate accounts of what are referred to as inference claims in the informal logic and argumentation literatures. (shrink)

Introduction by Christopher W. Tindale Argumentation Library, Volume 21. Dordrecht: Springer, 2012. Pp. xxi, 1-355. Hardcover US$149. Softcover US$24.95.

Corroborative evidence has a dual function in argument. Primarily, it functions to provide direct evidence supporting the main conclusion. But it also has a secondary, bolstering function which increases the probative value of some other piece of evidence in the argument. This paper argues that the bolstering effect of corroborative evidence is legitimate, and can be explained as counter–rebuttal achieved through inference to the best explanation. A model (argument diagram) of corroborative evidence, representing its structure and operation as a schematic (...) pattern of defeasible argument is also supplied. In addition to explaining the operation and theoretical foundation of corroborative evidence, the model facilitates the correct analysis and guides the evaluation (assessment and critique) of corroborative evidence as it occurs in argument. (shrink)

The authors of 200 arguments for questions posed 19 types of questions, justified them in 62 different ways, offered a justification of the question for 50 different types of purposes, and posed the question for 49 different types of purposes. Further consolidation of the categories used in the analysis is desirable and possible. Of the six most commonly posed types of questions, only three (yes-no questions, select questions, and either-or questions) are at first glance capable of formal representation in an (...) erotetic language of the sort described by Wiśniewski (1995, 1996, 2013), but all six (including also requests to explain, identify and find a means) can be represented formally using the interrogative operators devised by Kubiński (1980). As for the types of justification, four passages argued against posing a question by denying one of its presuppositions, a strategy that implies that a question without a true answer is not worth posing. Only 20 passages, however, argued for a question by asserting a presupposition – typically in cases where their addressees might think that the premissed presupposition is false. Close analysis of five passages randomly selected from the 200 turned up four distinct conditions assumed to be necessary for a question to be worth posing: absence of a false presupposition, a way of working out a correct answer, an unbiased answerer, and a need to answer the question. The first three of these conditions can generally be presumed to be satisfied, and would need to be mentioned in justifying a question only if there was a suspicion that they were not. The fourth condition, a need to answer the question, typically does need to be established, and was the genus of the types of justification identified in half of the passages arguing for a non-rhetorical question. The dominant purpose for justifying a question, found in 111 of the passages, was to establish a need to answer the question; given that justifying a question typically amounts to establishing a need to answer it, this purpose is internal to the practice. The most common generic purposes for posing the question for which an author argued were to provoke thought, to introduce subsequent discussion of the question, to indirectly claim something (in the case of rhetorical questions), to issue a challenge, and to seek enlightenment. (shrink)

A conclusion is a “material consequence” of reasons if it follows necessarily from them in accordance with a valid form of argument with content. The corresponding universal generalization of the argument’s associated conditional must be true, must be a covering generalization, and must be true of counter-factual instances. But it need not be law-like. Pearl’s structural model semantics is easier to apply to such counter-factual instances than Lewis’s closest-worlds semantics, and gives intuitively correct results.

The article develops and justifies, on the basis of the epistemological argumentation theory, two central pieces of the theory of evaluative argumentation interpretation: 1. criteria for recognizing argument types and 2. rules for adding reasons to create ideal arguments. Ad 1: The criteria for identifying argument types are a selection of essential elements from the definitions of the respective argument types. Ad 2: After presenting the general principles for adding reasons (benevolence, authenticity, immanence, optimization), heuristics are proposed for finding missing (...) reasons, for deductive arguments, e.g., semantic tableaux are suggested. (shrink)