This paper is an exercise in intellectual history, an attempt to understand how a specific term—”informal logic”— came to be interpreted in so many different ways. I trace the emergence and development of “informal logic” to help explain the many different meanings, how they emerged and how they are related. This paper is also, to some degree, an account of a movement that developed outside the mainstream of philosophy, whose origins lie in a desire to make logic useful (echoing Dewey).

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.

A popular three-stage argument appraisal strategy calls for (1) identifying the parts of the argument, (2) classifYing the argument as deductive, inductive, or some other type, and (3) appraising the argument using the standards appropriate for the type. This strategy fails for a number of reasons. I propose a comprehensive alternative approach that distinguishes between inductive, deductive, and other standards; calls for the successive application of standards combined with assumption-ascription, according to policies that depend for their selection on the goals (...) of the appraiser; and provides for qualified reasoning. (shrink)

In this paper, I propose that the inquiry known as a/the theory of argument is the “invention” of Trudy Govier, using that term in its rhetorical sense, viz., the process of choosing ideas appropriate to the subject. In her paper, “Is a Theory of Argument Possible?” Govier used the idea of theory of argument to focus her discussion on problems in argument analysis and evaluation that came to light in the 1970s and 1980s. The idea of a theory of argument (...) was already there but Govier “discovered” it in the sense that she made its potential clear. (shrink)

The view that contradictions cannot be true has been part of accepted philosophical theory since at least the time of Aristotle. In this regard, it is almost unique in the history of philosophy. Only in the last forty years has the view been systematically challenged with the advent of dialetheism. Since Graham Priest introduced dialetheism as a solution to certain self-referential paradoxes, the possibility of true contradictions has been a live issue in the philosophy of logic. Yet, despite the arguments (...) advanced by dialetheists, many logicians and philosophers still hold the opinion that contradictions cannot be true. -/- Rather than advocating the truth of certain contradictions, this thesis offers a different challenge to the classical logician. By showing that it can be philosophically coherent to propose that true contradictions are metaphysically possible, the thesis suggests that the classical logician must do more than she currently has to justify her confidence in the impossibility of true contradictions. Simply fighting off the dialetheist’s putative examples of true contradictions at the actual world isn’t enough to justify the classical logician’s conclusion that true contradictions are impossible. -/- To aid the thesis dialectically, we introduce a new position, absolutism, which hypothesises that it’s metaphysically possible for at least one contradiction to be true, contrasting with the dialetheic hypothesis that some contradictions are true in the actual world. We demonstrate that absolutism can be given a philosophically coherent interpretation, an appropriate logic, and that certain criticisms are completely toothless against absolutism. The challenge put to the classical logician is then: On what logical or philosophical grounds can we rule out the metaphysical possibility of true contradictions? (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)

We are often urged to figure things out for ourselves rather than to rely on other people’s say-so, and thus be ‘epistemically autonomous’ in one sense of the term. But why? For almost any important question, there will be someone around you who is at least as well placed to answer it correctly. So why bother making up your own mind at all? I consider, and then reject, two ‘egoistic’ answers to this question according to which thinking for oneself is (...) beneficial for the autonomous agent herself. I go on to suggest that the reason we should (sometimes) think for ourselves is that doing so (sometimes) increases the collective reliability of the epistemic community to which we belong. In many cases, this will do nothing at all to increase our own chances of forming correct beliefs. So, at least in this respect, the rationale for being epistemically autonomous is entirely ‘altruistic’. (shrink)

Rejectivism is one of the most influential embodiments of pragmatism within contemporary philosophy of logic, advancing an explanation of the meaning of a logical notion, negation, in terms of the speech act of denial. This paper offers a challenge to rejectivism by proposing that in virtue of explaining negation in terms of denial, the rejectivist ought to be able to explain the concept of contradiction partially in terms of denial. It is argued that any failure to achieve this constitutes an (...) explanatory failure on the part of rejectivism, and reasons are then provided to doubt that the challenge can be successfully met. (shrink)

How do Dutch people let each other know that they disagree? What do they say when they want to resolve their difference of opinion by way of an argumentative discussion? In what way do they convey that they are convinced by each other’s argumentation? How do they criticize each other’s argumentative moves? Which words and expressions do they use in these endeavors? By answering these questions this short essay provides a brief inventory of the language of argumentation in Dutch.

I will situate the fallacies approach to reasoning with the aim of making it more relevant to contemporary life and thus intellectually significant and valuable as a method for teaching reasoning. This entails a revision that will relegate some of the traditional fallacies to the realm of history and introduce more recently recognized problems in reasoning. Some newly recognized problems that demand attention are revealed by contemporary science studies, which reveal at least two tenacious problems in reasoning that I will (...) explore in this paper. One of these problems is androcentrism, a ubiquitous problem with reasoning that feminists exposed in the twentieth century but that continues to pervade people’s reasoning. The other is biological reductionism in at least two specific forms: genetic determinism and adaptationism. (shrink)

The Law of Non-Contradiction holds that both sides of a contradiction cannot be true. Dialetheism is the view that there are contradictions both sides of which are true. Crucial to the dispute, then, is the central notion of contradiction. My first step here is to work toward clarification of that simple and central notion: Just what is a contradiction?

Five errors that fit under the category of jumping to a conclusion are identified: (1) arguing from premises that are insufficient as evidence to prove a conclusion (2) fallacious argument from ignorance, (3) arguing to a wrong conclusion, (4) using defeasible reasoning without being open to exceptions, and (5) overlooking/suppressing evidence. It is shown that jumping to a conclusion is best seen not as a fallacy itself, but as a more general category of faulty argumentation pattern underlying these errors and (...) some related fallacies. (shrink)

This article synthesizes the results of several interviews with argumentation scholars from across the American continents to address three questions regarding the connections in argumentation studies between North and South/Central America: “What motivated the study of argumentation in the Americas?” “What commonalities, if any, exist in argumentation studies across the Americas?” and “What should the future of argumentation studies in the Americas look like?” Using these interviews in combination with existing textual sources, the article also provides motivated suggestions for directions (...) for the future of the community in the field. (shrink)

Jednym z najważniejszych celów kursów krytycznego myślenia powinno być dostarczenie słuchaczom narzędzi pomocnych w podejmowaniu trafnych decyzji w codziennym życiu. Podczas takich kursów wiele uwagi poświęca się zazwyczaj wyrabianiu u studentów umiejętności oceny argumentów. W niniejszym artykule próbuję odpowiedzieć na pytanie – jaka metoda oceny argumentów najlepiej nadaje się do zastosowania podczas kursów krytycznego myślenia? Jak sądzę, metoda taka powinna być możliwie najbardziej intuicyjna, „przyjazna użytkownikowi” – prosta zarówno do opanowania, jak i późniejszego stosowania. Są to warunki konieczne do tego, (...) aby osoby, które ukończyły kurs, faktycznie wykorzystywały ją w codzienny sytuacjach. W artykule opisuję metodę oceny argumentów, która, jak mi się wydaje, spełnia te warunki. Metoda ta opiera się przede wszystkim na koncepcjach S.N. Thomasa i M. Tokarza. Jej szczegóły, a także sposób prezentowania jej studentom, wypracowałem podczas prowadzonych przeze mnie kursów z zakresu logiki nieformalnej i krytycznego myślenia. (shrink)

Woods and Walton deserve credit for including a discussion of “economic reasoning” and its susceptibility to the “fallacy of composition.” Unfortunately, they did not sufficiently pursue the topic, and argumentation scholars have apparently ignored their pioneering effort. Yet, obviously, economic argumentation is extremely important, and economists constantly harp on this fallacy. This paper calls attention to this problem, elaborating my own approach, which is empirical, historical, and meta-argumentational.

Perelman's work has been very influential in various disciplines, among them philosophy, rhetoric and law. Especially the typology of argumentative schemes which he developed together with L. Olbrechts-Tyteca has been considered as an excellent classification of arguments in natural language. There are, however, some weaknesses of this typology which make its application to empirical research quite difficult, namely, the lack of explicitness and the absence of clear criteria of demarcation. Still, the typology is highly relevant for empirical research, if these (...) weaknesses are removed. This is illustrated with an example: the scheme called ‘the division of the whole into its parts’ by Perelman/Olbrechts-Tyteca is described explicitly and then applied to the analysis of a sample of everyday arguments (mostly taken from newspapers). (shrink)

Can argumentation schemes play a part in the critical processing of argumentation by lay people? In a qualitative study, participants were invited to come up with strong and weak arguments for a given claim and were subsequently interviewed for why they thought the strong argument was stronger than the weak one. Next, they were presented with a list of arguments and asked to rank these arguments from strongest to weakest, upon which they were asked to motivate their judgments in an (...) interview. In order to assess whether lay people apply argument scheme specific criteria when performing these tasks, five different argumentation schemes were included in this study: argumentation from authority, from example, from analogy, from cause to effect, and from consequences. Laypeople’s use of criteria for argument quality was inferred from interview protocols. The results revealed that participants combined general criteria from informal logic and scheme-specific criteria. The results supported the conventional validity of the pragma-dialectical argument scheme rule in a strong sense and provided a more fine-grained view of central processing in the Elaboration Likelihood Model. (shrink)

Since the 80s, educators have supported instruction in critical thinking as “an Educational Ideal.” This should not be a surprise given some of the more common conceptions, e.g., Ennis’s “reasonable reflective thinking on what to believe or do,” or Siegel’s “being appropriately moved by reasons,” as opposed to bias, emotion or wishful thinking. Who would want a doctor, lawyer, or mechanic who could not skillfully evaluate arguments, causes, and cures? So, educators endorsed the dream that, through proper CT instruction, students’ (...) critical skills and “rational passions” could be greatly improved. In spite of the dream’s appeal, the reality is, after 30+ years, there is little reason to think the dream resembles reality. After describing what I take to be an adequate definition of CT, such a depressing conclusion will be supported by CT assessment scores from across academe, the continued widespread disagreement among experts in nearly all fields, including CT, and the abundant psychological research on rationality and decision making. And finally, while the ideal extols the value of objectivity, I shall argue that bias may be unavoidable because personal values play a vital role in the evaluation of many arguments. (shrink)

Informal logic has expanded the concept of an 'argument' beyond that presented traditionally by formal logicians-to include arguments as encountered in 'real-life'. Existent definitions of argument structure are argued to be inadequate by failing to fully recognise that, ultimately, arguments have a human source. Accordingly, a new definition is proposed which appeals to relevant cognitive and behavioural factors. The definition retains some traditional concepts, but introduces the term 'supportive' as a modification to 'premiss'. The concept of a 'persuader' is also (...) developed. The definition is argued to capture more fully the intricacies, subtleties and rich diversity of informal arguments. (shrink)

In this article it is argued that a complex model that includes Toulmin's functional account of argument, the pragma-dialectical stage analysis of argumentation offered by the Amsterdam School, and criteria developed in critical thinking theory, can be used to account for the normativity and field-dependence of argumentation in science. A pragma-dialectical interpretation of the four main elements of Toulmin's model, and a revised account of the double role of warrants, illuminates the domain specificity of scientific argumentation and the restrictions to (...) which the confrontation and opening stages of scientific critical discussions are subjected. In regard to the argumentation stage, examples are given to show that a general account of argumentation, as advocated by informal logicians, is not applicable to arguments in science. Furthermore, although patterns of inference differ in various scientific practices, deductive validity is argued to be a crucial notion in the assessment of scientific arguments. Finally, some remarks are made concerning the burden of proof and the concluding stage of scientific argumentation. (shrink)

Towards a Research Agenda for Informal Logic and Critical Thinking.

Philosophy and Literature is an internationally renowned refereed journal founded by Denis Dutton at the University of Canterbury, Christchurch. It is now published by the Johns Hopkins University Press. Since its inception in 1976, Philosophy and Literature has been concerned with the relation between literary and philosophical studies, publishing articles on the philosophical interpretation of literature as well as the literary treatment of philosophy. Philosophy and Literature has sometimes been regarded as iconoclastic, in the sense that it repudiates academic pretensions, (...) insidious jargon and institutional vogue. Dutton, who remains the editor, still writes a regular column. A distinctive feature of Philosophy and Literature was the annual Bad Writing Contest, held from 1995–98, which sought to identify (and publish) the ‘most stylistically lamentable passages’ of academic prose, often to great amusement. (shrink)

Over the last few years, there have been five best sellers critical of religion and religious belief. It seems that there is great interest in questions about religious belief. Ironically, critical thinking texts seldom examine the topic. This paper will evaluate eight arguments to exempt religious belief from rational critique. I conclude that the topic of religious belief should not be exempt from critical thinking classes.