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.

The issue of the relationship between formal and informal logic depends strongly on how one understands these two designations. While there is very little disagreement about the nature of formal logic, the same is not true regarding informal logic, which is understood in various (often incompatible) ways by various thinkers. After reviewing some of the more prominent conceptions of informal logic, I will present my own, defend it and then show how informal logic, so understood, is complementary to formal logic.

This volume presents mathematical game theory as an interface between logic and philosophy.

Hamblin held that the conception of 'fallacy' as an argument that seems valid but is not really so was the dominant conception of fallacy in the history of fallacy studies. The present paper explores the extent of support that there is for this view. After presenting a brief analysis of 'the standard definition of fallacy,' a number of the definitions of 'fallacy' in texts from the middle of this century – from the standard treatment – are considered. This is followed (...) by a review of the definitions of 'fallacy' in the earlier history of logic books, including those of Aristotle, Whately, Mill and De Morgan. The essay concludes that there is scarcely any support for Hamblin's view that this particular definition of 'fallacy' was widely held. (shrink)

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).

This article analyses the fallacy of wrenching from context, using the dialectical notions of commitment and implicature as tools. The data, a set of key examples, is used to sharpen the conceptual borderlines around the related fallacies of straw man, accent, misquotation, and neglect of qualifications. According to the analysis, the main characteristics of wrenching from context are the manipulation of the meaning of the other’s statement through devices such as the use of misquotations, selective quotations, and quoting out of (...) context. The theoretical tools employed in the analysis are pragmatic theories of meaning and a dialectical model of commitment, used to explain how and why a standpoint is distorted. The analysis is based on a conception of fallacies as deceptive strategic moves in a game of dialogue. As a consequence, our focus is not only on misquotations as distortions of meaning, but on how they are used as dialectical tools to attack an opponent or win a dispute. Wrenching from context is described as a fallacy of unfairly attributing a commitment to another party that he never held. Its power as a deceptive argumentation tactic is based on complex mechanisms of implicit commitments and on their misemployment to improperly suggest an attribution of commitment. (shrink)

In this paper we study the inferential analysis of the use of fallacies as a source of absurd communication. Starting from a diachronic review of perpectives, criteria and classification of fallacies, we analyze the fallacious arguments used in absurd discourses which are meant to trigger humor as well as the dislocation of the communicative sense.

In Fallacies and Judgments of Reasonableness, Frans H. van Eemeren, Bart Garssen and Bert Meuffels report on their systematic empirical research of the conventional validity of the pragma-dialectical discussion rules. The experimental studies they carried out during more than ten years start from the pragma-dialectical theory of argumentation developed at the University of Amsterdam, their home university. In these studies they test methodically the intersubjective acceptability of the rules for critical discussion proposed in this theory by confronting ordinary arguers who (...) have not received any special education in argumentation and fallacies with discussion fragments containing both fallacious and non-fallacious argumentative moves. The research covers a wide range of informal fallacies. In this way, the authors create a basis for comparing the theoretical reasonableness conception of pragma-dialectics with the norms for judging argumentative moves prevailing in argumentative practice. Fallacies and Judgments of Reasonableness provides a unique insight into the relationship between theoretical and practical conceptions of reasonableness, supported by extensive empirical material gained by means of sophisticated experimental research. (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.

Even with Kientpointer's and Walton's valuable work, we do not yet have a complete theory of argument schemes. A complete theory of argument schemes should contain at least the following: its theoretical motivation, the denotation of "argument" or "ar gumentation" used in the theory, an analysis of the concept of an argument scheme, a theory of classification of argument schemes, a solution to the problem of identifying which scheme is correct, and an account of the grounds of the normativity or (...) normat ive argument schemes. The paper will supply these elements, worked out as fully as space permits. (shrink)

The main thrust of the argument of this thesis is to show the possibility of articulating a method of construction or of synthesis--as against the most common method of analysis or division--which has always been (so we shall argue) a necessary component of scientific theorization. This method will be shown to be based on a fundamental synthetic logical relation of thought, that we shall call inversion--to be understood as a species of logical opposition, and as one of the basic monadic (...) logical operators. Thus the major objective of this thesis is to This thesis can be viewed as a response to Larry Laudan's challenge, which is based on the claim that ``the case has yet to be made that the rules governing the techniques whereby theories are invented (if any such rules there be) are the sorts of things that philosophers should claim any interest in or competence at.'' The challenge itself would be to show that the logic of discovery (if at all formulatable) performs the epistemological role of the justification of scientific theories. We propose to meet this challenge head on: a) by suggesting precisely how such a logic would be formulated; b) by demonstrating its epistemological relevance (in the context of justification) and c) by showing that a) and b) can be carried out without sacrificing the fallibilist view of scientific knowledge. OBJECTIVES: We have set three successive objectives: one general, one specific, and one sub-specific, each one related to the other in that very order. (A) The general objective is to indicate the clear possibility of renovating the traditional analytico-synthetic epistemology. By realizing this objective, we attempt to widen the scope of scientific reason or rationality, which for some time now has perniciously been dominated by pure analytic reason alone. In order to achieve this end we need to show specifically that there exists the possibility of articulating a synthetic (constructive) logic/reason, which has been considered by most mainstream thinkers either as not articulatable, or simply non-existent. (B) The second (specific) task is to respond to the challenge of Larry Laudan by demonstrating the possibility of an epistemologically significant generativism. In this context we will argue that this generativism, which is our suggested alternative, and the simplified structuralist and semantic view of scientific theories, mutually reinforce each other to form a single coherent foundation for the renovated analytico-synthetic methodological framework. (C) The third (sub-specific) objective, accordingly, is to show the possibility of articulating a synthetic logic that could guide us in understanding the process of theorization. This is realized by proposing the foundations for developing a logic of inversion, which represents the pattern of synthetic reason in the process of constructing scientific definitions. (shrink)