Douglas Walton’s multitudinous contributions to the study of argumentation seldom, if ever, directly engage with argumentation in mathematics. Nonetheless, several of the innovations with which he is most closely associated lend themselves to improving our understanding of mathematical arguments. I concentrate on two such innovations: dialogue types (§1) and argumentation schemes (§2). I argue that both devices are much more applicable to mathematical reasoning than may be commonly supposed.

The quality of our public discourse – think of the climate change debate for instance – is never very high. A day spent observing it reveals a litany of misrepresentation and error, argumentative fallacy, and a general lack of good will. In this paper I focus on a microcosmic aspect of these practices: the use of two types of argument – the argumentum ad hominem and appeal to authority – and a way in which they are related. Public debate is (...) so contaminated by the misuse of the ad hominem tactic that it is important to have an understanding of one of the ways in which its use may be legitimate. So readers who might have expected an analysis of the ad hominem fallacy will, on the contrary, be presented with an account of one of the places for its potential success. In ad hominem, arguers are viewed as legitimate constitutive targets for their own argument; in authority arguments, arguers provide a legitimate constitutive warrant for an argument they deploy. These types of argument are connected in so far as the identities of persons deploying them carry the cognitive weight of the argument. If authority arguments sometimes deserve to succeed, ad hominem attacks on them are potentially legitimate. An important motivation for this analysis is that in identifying the success conditions for one of the ad hominem types we attain some clarity in the evaluation of their use. (shrink)

The relationship between knowledge, belief, and ethics is an inaugural theme in philosophy; more recently, under the title “ethics of belief” philosophers have worked to develop the appropriate methodology for studying the nexus of epistemology, ethics, and psychology. The title “ethics of belief” comes from a 19th-century paper written by British philosopher and mathematician W.K. Clifford. Clifford argues that we are morally responsible for our beliefs because each belief that we form creates the cognitive circumstances for related beliefs to follow, (...) and we inevitably influence each other through those beliefs. This study argues that recent cognitive research supports Cliffordian insights regarding patterns of belief formation and social influence. From the confirmation offered by such research, it follows that informational accuracy holds serious ethical significance in public discourse. Although scientific and epistemological matters are not always thought to be linked to normative morality, this study builds on Clifford's initial insights to show their linkage is fundamental to inquiry itself. In turn, Clifford's ethical and epistemic outline can inform a framework grounded in “public reason” under which seemingly opposed science communication strategies are philosophically united. With public discourse on climate change as the key example, empirically informed and grounded strategies for science communication in the public sphere are considered. (shrink)

We have noticed a pattern of arguments that exhibit a type of irrationality or a particular informal logical fallacy that is not fully captured by any existing fallacy. This fallacy can be explored through three examples where one misattributes a cause by focusing on a smaller portion of a larger set—specifically, the last or least known—and claiming that that cause holds a unique priority over other contributing factors for the occurrence of an event. We propose to call this fallacy the (...) “last straw fallacy” and will argue why these examples actually warrant a new logical name. Finally, we will show how these cases point to a deeper insight about the contexts in which we typically invoke this type of reasoning and some significant harmful consequences of doing so. (shrink)

Mathematicians often speak of conjectures, yet unproved, as probable or well-confirmed by evidence. The Riemann Hypothesis, for example, is widely believed to be almost certainly true. There seems no initial reason to distinguish such probability from the same notion in empirical science. Yet it is hard to see how there could be probabilistic relations between the necessary truths of pure mathematics. The existence of such logical relations, short of certainty, is defended using the theory of logical probability (or objective Bayesianism (...) or non-deductive logic), and some detailed examples of its use in mathematics surveyed. Examples of inductive reasoning in experimental mathematics are given and it is argued that the problem of induction is best appreciated in the mathematical case. (shrink)

Introduction: Clinical practice guidelines (CPGs) are an important source of justification for clinical decisions in modern evidence-based practice. Yet, we have given little attention to how they argue their evidence. In particular, how do CPGs argue for treatment with long-term medications that are increasingly prescribed to older patients? Approach and rationale: I selected six disease-specific guidelines recommending treatment with five of the medication classes most commonly prescribed for seniors in Ontario, Canada. I considered the stated aims of these CPGs and (...) the techniques employed towards those aims. Finally, I reconstructed and logically analysed the arguments supporting recommendations for pharmacotherapy. Analysis: The primary function of CPGs is rhetorical, or persuasive, and their means of persuasion include both a display of their credibility and their argumentation. Arguments supporting pharmacotherapy recommendations for the target population follow a common inductive pattern: statistical generalization from randomized controlled trial (RCT) and meta-analysis evidence. Two of the CPGs also argue their treatment recommendations for older patients in this style, while three fail to justify pharmacotherapy specifically for the older population. Discussion: The arguments analysed lack the auxiliary assumptions that would warrant making a generalization about the clinical effectiveness of medications for the older population. Guidelines reason using simple induction, while ignoring important inferential gaps. Future guidelines should aspire to be well-reasoned rather than simply evidence-based; argue from a plurality of evidence; be wary of hasty inductions; appropriately limit the scope of their recommendations; and avoid making law-like, prescriptive generalizations. (shrink)

Bayesian reasoning has been applied formally to statistical inference, machine learning and analysing scientific method. Here I apply it informally to more common forms of inference, namely natural language arguments. I analyse a variety of traditional fallacies, deductive, inductive and causal, and find more merit in them than is generally acknowledged. Bayesian principles provide a framework for understanding ordinary arguments which is well worth developing.

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.

Las definiciones de argumentación son tan variadas como las distintas posiciones existentes en torno a la pregunta de qué hacemos exactamente cuando argumentamos y cuándo estamos, de hecho, argumentando. Incluso el mismo autor puede ofrecer más de una definición de lo que entiende por argumentación; en parte, porque el problema de la argumentación no se circunscribe a un solo ámbito, ni del conocimiento ni de la vida práctica.

The Consequence Argument has elicited various responses, ranging from acceptance as obviously right to rejection as obviously problematic in one way or another. Here we wish to focus on one specific response, according to which the Consequence Argument begs the question. This is a serious accusation that has not yet been adequately rebutted, and we aim to remedy that in what follows. We begin by giving a formulation of the Consequence Argument. We also offer some tentative proposals about the nature (...) of begging the question. Although the charge of begging the question is frequently made in philosophy, it is surprisingly difficult to pin down the precise nature of this dialectical infelicity (or family of such infelicities). Thus we offer some new proposals about the nature of begging the question with an eye to understanding what is going on in central cases in which the charge is legitimately made. We then defend the Consequence Argument against the charge that it begs the question, so construed. We contend that, whatever the other liabilities of the argument may be, it does not beg the question against the compatibilist. (shrink)

The present study examined how the pre-war debate of the US decision to invade Iraq (in March 2003) was discursively constructed in the US/British mainstream newspaper opinion/editorial (op/ed) argumentation. Drawing on theoretical insights from critical discourse analysis and argumentation theory, I problematised the fallacious discussion used in the pro-war op/eds to build up a ‘moral/legal case’ for war on Iraq based on adversarial (rather than dialogical) argumentation. The proponents of war deployed ‘instrumental rationality’ (ends-justify-means reasoning), ‘ethical necessity’ (Bush’s ‘Preemption Doctrine’) (...) and ‘humanitarian virtue’ (the bombing of Iraq to ‘save’ Iraqis from Saddam’s pestilent tyranny) to justify the pending invasion of Iraq. Their arguments intertextually resonated with Bush administration’s ‘war on terror’ rhetoric in a way that created a form of indexical association through ‘recontextualisation’. The type of arguments marshalled by the pro-war op/ed commentators uncritically bolstered the set of US official ‘truth claims’ and ‘presuppositions’. (shrink)

J. Anthony Blair is a prominent international figure in argumentation studies. He is among the originators of informal logic, an author of textbooks on the informal logic approach to argument analysis and evaluation and on critical thinking, and a founder and editor of the journal Informal Logic. Blair is widely recognized among the leaders in the field for contributing formative ideas to the argumentation literature of the last few decades. This selection of key works provides insights into the history of (...) the field of argumentation theory and various related disciplines. It illuminates the central debates and presents core ideas in four main areas: Critical Thinking, Informal Logic, Argument Theory and Logic, Dialectic and Rhetoric. (shrink)

The contribution critically discusses Walton's argumentation scheme approach. On the one hand, its enormous richness and closeness to the empirical argumentation material is appreciated, but, on the other, fundamental conceptual weaknesses are revealed. Although the approach more recently has been declared to strive for “true beliefs and correct choices” it has not systematically developed the proposed schemes in a way that these goals are reached. Accordingly, many proposed schemes are fallacious from an epistemological standpoint.

Both because of the vagueness of the word ‘give’ when speaking about giving reasons, and because we lack an adequate definition of ‘reasons’, there is a harmful ambiguity in the expression ‘giving reasons’. Particularly, straightforwardly identifying argumentation with reasons giving would make of virtually any interplay a piece of argumentation. Besides, if we adopt the mainstream definition of reasons as “considerations that count in favour of doing or believing something”, then only good argumentation would count as argumentation. In this paper, (...) I defend a qualified characterization of argumentation as reasons giving that is shown to be fruitful for shedding light on the practice of giving reasons, and an inferentialist conception of reasons that makes room for speaking of “bad reasons” and, consequently, makes it possible to talk of argumentation as reasons giving even if we are talking about bad argumentation. (shrink)

Collaborative learning with cases characteristically involves discussing and developing shared explanations. We investigated the argumentation scheme which learners use in constructing shared explanations over evidence. We observed medical students attempting to explain how a judge had arrived at his verdict in a case of medical negligence. The students were learning within a virtual learning environment and their communication was computer mediated. We identify the dialogue type that these learners construct and show that their argumentation conforms with an abductive form of (...) argumentation scheme (‘inference to the best explanation’). We also assessed the students’ learning and propose that it is related to particular features of this argumentation scheme. (shrink)

It is obvious that teaching and research in informal logic is a growth industry, indeed one of burgeoning proportions. Judging by skyrocketing enrolments and the avalanche of books, journals, computer aids, conferences, and workshops during the last decade, it would seem to be no passing fad but the overdue recognition of a societal need.

This volume contains 12 papers addressed to researchers and advanced students in informal logic and related fields, such as argumentation, formal logic, and communications. Among the issues discussed are attempts to rethink the nature of argument and of inference, the role of dialectical context, and the standards for evaluating inferences, and to shed light on the interfaces between informal logic and argumentation theory, rhetoric, formal logic and cognitive psychology.

Toward a Shared Metaphoric Meaning in Children's Discourse: The Role of Argumentation The text deals with the phenomenon of understanding and interpreting metaphoric expressions in children. Of the many metaphoric figures, one type was selected: the ‘so-called’ psychological-physical metaphors that illuminate a psychological experience by appealing to an event in the physical domain. The data consist of children's discussions in pairs, in which they make a joint interpretation of metaphors including a dual-function adjective, e.g., a hard person, a sweet person, (...) an empty person. A hundred and forty-four dialogues between peer dyads were recorded from three age groups : 6;6-7;6, 8;6-9;6, and 10;6-11;6. The children's task was to prepare an interpretation of metaphorical expressions for two television quiz shows, one for peers and one for young preschoolers. The research design was balanced for age, gender, and order of metaphoric interpretation in the two experimental variants. Following Quignard's model, we analyzed children's argumentation as a particular case of dialogical problem solving, whereby children had to understand the metaphoric meaning and convey it to the potential addressee. The results show an interesting dynamic in the argumentative orientation of the pro and the contra type, depending on the age of interlocutors. The frequency of metaphoric interpretations in opposition to those presented by the partner decreases with the children's age, but the frequency of compound proposals with the use of the partner's contribution increases. For the younger addressee, children most frequently interpret metaphors as descriptions of magical situations. (shrink)

Much psychological research on argumentation focuses on persuasion and pragmatics. However, one strand investigates how average people understand the nature of knowledge and knowing, and how these epistemological orientations underlie skilled argumentation. The research reviewed addresses the question whether the normative emphasis of the philosophical epistemological approach to argumentation matches psychological findings. The empirical research reviewed concerns the relationship between personal episte- mological understanding and three aspects of argument: argument construction, identification of informal reasoning fallacies, and orientation toward explanation or (...) evidence. Findings suggest that people develop an epistemological approach toward argumentation in which beliefs about knowledge justification requirements are related with skilled argumentation. (shrink)

This discussion reviews the thinking of some prominent philosophers of argument to extract principles common to their thinking. It shows that a growing concern with dialogical pragmatics is better appreciated as a part of applied ethics than of applied epistemology. The discussion concludes by indicating a possible consequence for philosophy of argument and invites further discussion by asking whether argumentation philosophy has an implicit, underlying moral, or even political, posture.

The study describes a method created for the analysis of persuasive strategies, called rhetorical heuristics, which can be applied in speeches where the argument focuses primarily on questions of fact. First, the author explains how the concept emerged from the study of classical oratory. Then the theoretical background of rhetorical heuristics is outlined through briefly discussing relevant aspects of the psychology of decision-making. Finally, an exposition of how one could find these persuasive strategies introduces rhetorical heuristics in more detail.

In this paper we describe a method for the specification of computationalmodels of argument using dialogue games. The method, which consists ofsupplying a set of semantic definitions for the performatives making upthe game, together with a state transition diagram, is described in full.Its use is illustrated by some examples of varying complexity, includingtwo complete specifications of particular dialogue games, Mackenzie's DC,and the authors' own TDG. The latter is also illustrated by a fully workedexample illustrating all the features of the game.

This volume reflects the development and theoretical foundation of a new paradigm for critical thinking based on inquiry. The field of critical thinking, as manifested in the Informal Logic movement, developed primarily as a response to the inadequacies of formalism to represent actual argumentative practice and to provide useful argumentative skills to students. Because of this, the primary focus of the field has been on informal arguments rather than formal reasoning. Yet the formalist history of the field is still evident (...) in its emphasis, with respect to both theory and pedagogy, on the structure and evaluation of individual, de-contextualized arguments. It is our view that such a view of critical thinking is excessively narrow and limited, failing to provide an understanding of argumentation as largely a matter of comparative evaluation of a variety of contending positions and arguments with the goal of reaching a reasoned judgment on an issue. As a consequence, traditional critical thinking instruction is problematic in failing to provide the reasoning skills that students need in order to accomplish this goal. Instead, the goal of critical thinking instruction has been seen largely as a defensive one: of learning to not fall prey to invalid, inadequate, or fallacious arguments. (shrink)

The commonalities of Douglas Walton's Slippery Slope Arguments and James Davies's Ways of Thinking are obvious: both are written by Canadian philosophers; both lie within the broad field of informal logic; and both make appeals in support of dialogical reasoning. But there the similarities end. The former is the work of a prolific author writing a treatise focussing narrowly on one topic within informal logic; the latter is the product of a newcomer to book-writing, and his is a textbook intended (...) for beginning students. (shrink)

Criticism may degenerate into quibbling or nitpicking. How can discussants keep quibblers under control? In the paper we investigate cases in which a battle about words replaces a discussion of the matters that are actually at issue as well as cases in which a battle about minor objections replaces a discussion of the major issues. We survey some lines of discussion dealing with these situations in profiles of dialogue.

According to a simple form of consequentialism, we should base decisions on our judgments about their consequences for achieving our goals. Our goals give us reason to endorse consequentialism as a standard of decision making. Alternative standards invariably lead to consequences that are less good in this sense. Yet some people knowingly follow decision rules that violate consequentialism. For example, they prefer harmful omissions to less harmful acts, they favor the status quo over alternatives they would otherwise judge to be (...) belter, they provide third-party compensation on the basis of the cause of an injury rather than the benefit from the compensation, they ignore deterrent effects in decisions about punishment, and they resist coercive reforms they judge to be beneficial. I suggest that nonconsequentialist principles arise from overgeneralizing rules that are consistent with consequentialism in a limited set of cases. Commitment to such rules is detached from their original purposes. The existence of such nonconsequentialist decision biases has implications for philosophical and experimental methodology, the relation between psychology and public policy, and education. (shrink)

Argumentation logicians have recognized a specter of relativism to haunt their philosophy of argument. However, their attempts to dispel pernicious relativism by invoking notions of a universal audience or a community of model interlocutors have not been entirely successful. In fact, their various discussions of a universal audience invoke the context-eschewing formalism of Kant’s categorical imperative. Moreover, they embrace the Kantian method for resolving the antinomies that continually vacillates between opposing extremes – here between a transcendent universal audience and a (...) context-embedded particular audience. This tack ironically restores the very external mediation they thought to obviate in their aim to ‘dethrone’ the absolutism and totalitarianism of formal logic with a democratic turn to audience adherence, the acceptability of premises and inferential links, and a contextual, or participant-relative, notion of cogency. (shrink)

Wesley Salmon and Michael Martin argue that scientific considerations about the order in the universe justify atheism. After sketching Salmon’s argument, I examine the nature of begging the question and argue that Martin takes a sufficient condition of that fallacy to be a necessary condition. After a pragmatic account to the fallacy is recommended, I point out how Salmon’s and Martin’s beg the question against all save those who already adhere to atheism and that the crucial considerations that they take (...) to be distinctly scientific are really extra-scientific considerations, giving a specious impression that they are uncontroversial to all who accept mainstream science. (shrink)

If dialogue is a necessary condition for argument, argumentation in oratory becomes questionable, since rhetoric is not a dialogically structured activity. If special norms apply to the ‘solo’ performances of rhetoric, the orator’s activity may be more appropriately described as reasoning than as arguing. By analyzing in what respect rhetorical texts can be interpreted as dialogue-based and subject to criteria of Informal Logic, the virtues of rhetorical argumentation in contrast to logic and dialectic emerge.

lt is now commonplace in fallacy inquiry for many of the traditional informal fallacies to be viewed as reasonable or nonfallacious modes of argument. Central to this evaluative shift has been the attempt to examine traditional fallacies within their wider contexts of use. However, this pragmatic turn in fallacy evaluation is still in its infancy. The true potential of a contextual approach in the evaluation of the fallacies is yet to be explored. I examine how, in the context of scientific (...) inquiry, certain traditional fallacies function by conferring epistemic gains upon inquiry. Specifically, I argue that these fallacies facilitate the progression of inquiry, particularly in the initial stages ofinquiry when the epistemic context is one of uncertainty. The conception of these fallacies that emerges is that of heuristics of reasoning in contexts of epistemic uncertainty. (shrink)