A comprehensive introduction to formal logic, Logic and Philosophy: A Modern Introduction is a rigorous yet accessible text, appropriate for students encountering the subject for the first time. Abundant, carefully crafted exercise sets accompanied by a clear, engaging exposition build to an exploration of sentential logic, first-order predicate logic, the theory of descriptions, identity, relations, set theory, modal logic, and Aristotelian logic. And as its title suggests, Logic and Philosophy is devoted not only to logic but also to the philosophical (...) debates that led to the development of the field. Much new material has been added for the 13th edition. An introduction to set theory and its relationship to logic and mathematics, including philosophical issues, is now part of Chapter 13. Chapter 15 is an introduction to modal logic and Kripke semantics, concluding with a discussion of philosophical problems with any logical accommodation of modalities. Instructors who do not wish to present proof methods will find chapters on truth trees for both sentential and first-order logic, and a presentation of trees for modal logic. Special features of this text include presentations of the history of logic, alternatives to traditional methods of conditional and indirect proof, and a discussion of semantic problems with universal and existential instantiations. Throughout, the authors are sensitive to philosophical issues that arise from the relationship between ordinary language, symbolic logic, and justifications for the syntax and semantics of the various symbolic languages. Discussions range from the justification of the truth table for the sentential rendering of if... then statements to semantic and syntactic paradoxes, including some troubling paradoxes that arise in ordinary language (e.g., the so-called hangman or surprise quiz paradox). Logic and Philosophy includes ample material for a one-semester or two-semester course and provides a thorough preparation for more advanced logic courses. (shrink)

Denying the antecedent is an invalid form of reasoning that is typically identified and frowned upon as a formal fallacy. Contrary to arguments that it does not or at least should not occur, denying the antecedent is a legitimate and effective strategy for undermining a position. Since it is not a valid form of argument, it cannot prove that the position is false. But it can provide inductive evidence that this position is probably false. In this role, it is neither (...) defective nor deceptive. Denying the antecedent provides inductive support for rejecting a claim as improbable. (shrink)

In this paper, I examine the incessant call to theory that is evident in fallacy inquiry. I relate the motivations for this call to a desire to attain for fallacy inquiry certain attributes of the theoretical process in scientific inquiry. I argue that these same attributes, when pursued in the context of philosophical inquiry in general and fallacy inquiry in particular, lead to the assumption of a metaphysical standpoint. This standpoint, I contend, is generative of unintelligibility in philosophical discussions of (...) rationality. I claim that this same unintelligibility can be shown to characterise fallacy inquiry, an example of the study of argumentative rationality. The context for my claim is an examination of the theoretical pronouncements of two prominent fallacy theorists, John Woods and Douglas Walton, in relation to the argument from ignorance fallacy. My conclusion takes the form of guidelines for the post-theoretical pursuit of fallacy inquiry. (shrink)

Criticisms of fallacy theory have been lodged from many different directions. In this paper, I consider the classic criticism of incompleteness by DeMorgan, Finocchiaro's claim that fallacies probably exist only in the mind of the interpreter, McPeck's claim that fallacies are at best context-dependent and Paul's complaints about the teaching of fallacies. I seek not merely to defend fallacy theory against unfair criticisms but also to learn from the criticisms what can be done in order to make fallacy theory a (...) viable theory of criticism. I argue that this will involve several changes: rethinking of the nature of fallacy; addressing some theoretical issues; and presenting fallacy theory in a more rigorous fashion. The paper concludes with reflections on how Quine's ontological advice about the resolution of ontological disputes might be applied to the issue of whether or not there are fallacies. (shrink)

This essay proposes and defends a general thesis concerning the nature of fallacies of reasoning. These in distinctive ways are all said to be deductively invalid. More importantly, the most accurate, complete and charitable reconstructions of these species and specimens of the informal fallacies are instructive with respect to the individual character of each distinct informal fallacy. Reconstructions of the fallacies as deductive invalidities are possible in every case, if deductivism is true, which means that in every case they should (...) be formalizable in an expressively comprehensive formal symbolic deductive logic. The general thesis is illustrated by a detailed examination of Walter Burleigh's paradox in his c. 1323 work, De Puritate Artis Logicae Tractatus Longior (Longer Treatise on the Purity of Logic), as a challenge to the deductive validity of hypothetical syllogism. The paradox has the form, ‹If I call you a swine, then I call you an animal; if I call you an animal, then I speak truly; therefore, if I call you a swine, then I speak truly'. Several solutions to the problem are considered, and the inference is exposed as an instance of the common deductive fallacy of equivocation. (shrink)

Several of the so-called “fallacies” in Aristotle are not in fact mistaken inference-types, but mistakes or breaches of rules in the questioning games which were practiced in the Academy and in the Lyceum. Hence the entire Aristotelian theory of “fallacies” ought to be studied by reference to the author's interrogative model of inquiry, based on his theory of questions and answers, rather than as a part of the theory of inference. Most of the “fallacies” mentioned by Aristotle can in fact (...) be diagnosed by means of the interrogative model, including petitio principii, multiple questions, “babbling’, etc., and so can Aristotle's alleged anticipation of the fallacy of argumentum ad hominem. The entire Aristotelian conception of inquiry is an interrogative one. Deductive conclusions caught Aristotle's attention in the form of answers that every rational interlocutor must give, assuming only his own earlier answers. Several features of Aristotle's methodology can be understood by means of the interrogative model, including the role of endoxa in it. Theoretically, there is also considerable leeway as to whether “fallacies” are conceived of as mistakes in questioning or as breaches of the rules that govern questioning games. (shrink)

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)

Fallacies are things people commit, and when they commit them they do something wrong. What kind of activities are people engaged in when they commit fallacies, and in what way are they doing something wrong? Many different things are called fallacies. The diversity of the use of the concept of a fallacy suggests that we are dealing with a family of cases not related by a common essence. However, we suggest a simple account of the nature of fallacies which encompasses (...) them all, viz., the term “fallacy” is our most general term for criticizing any general procedure used for the fixation of beliefs that has an unacceptably high tendency to generate false or unfounded beliefs, relative to that method of fixing beliefs. Very different sorts of things called fallacies are examined in the light of this account, e.g., denying the antecedent, circular arguments, so-called informal fallacies, and propositions said to be fallacies. We do not provide a theory of fallacies. Still, on our account pretty much all of those things that have been called fallacies are fallacies, and they have been called fallacies for pretty much the same reasons. (shrink)

The paper argues that the two best known formal logical fallacies, namely denying the antecedent (DA) and affirming the consequent (AC) are not just basic and simple errors, which prove human irrationality, but rather informational shortcuts, which may provide a quick and dirty way of extracting useful information from the environment. DA and AC are shown to be degraded versions of Bayes’ theorem, once this is stripped of some of its probabilities. The less the probabilities count, the closer these fallacies (...) become to a reasoning that is not only informationally useful but also logically valid. (shrink)

In the pragma-dialectical approach, fallacies are considered incorrect moves in a discussion for which the goal is successful resolution of a dispute. Ten rules are given for effective conduct at the various stages of such a critical discussion (confrontation, opening, argumentation, concluding). Fallacies are discussed as violations of these rules, taking into account all speech acts which are traditionally recognized as fallacies. Special attention is paid to the role played by implicitness in fallacies in everyday language use. It is stressed (...) that identifying and acknowledging fallacies in ordinary discussions always has a conditional character. Differences between the pragma-dialectical perspective, the Standard Treatment, and the formal logic approach to fallacy analysis are discussed. (shrink)

The authors contend that most contemporary logic textbooks fail the average student because they emphasize the evaluation of arguments over their clarification, assuming that the student already understands what motivations underlie logic.

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

The authors contend that most contemporary logic textbooks fail the average student because they emphasize the evaluation of arguments over their clarification, assuming that the student already understands what motivations underlie logic.

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

INTRODUCTION The present volume offers a selection of papers written by Tadeusz Czezowski. one of the most prominent representatives of the Lvov-Warsaw ...

Informal logic is an attempt to develop a logic that can assess and analyze the arguments that occur in natural language discourse. Discussions in the field may address instances of scientific, legal, and other technical forms of reasoning, but the overriding aim has been a comprehensive account of argument that can explain and evaluate the arguments found in discussion, debate and disagreement as they manifest themselves in daily life — in social and political commentary; in news reports and editorials in (...) the mass media ; in advertising and corporate and governmental communications; and in personal exchange. (shrink)

The University of Warsaw has a splendid modern library with 60,000 m 2 of floor space. It resembles a shopping centre. The long and elegant modern building on ulica Dobra, on the low ground between the old University and the Vistula, was opened in 1998 replacing the previous hopelessly inadequate facilities. It has an imposing sequence of copper-green “great texts” on its front side in Greek, Arabic, Sanskrit, Hebrew, Latin, Polish, music, and mathematics. These are international symbols, posting Warsaw’s claim (...) to international status. But inside, once one has passed the mall -like coffee-shop. (shrink)

The main thesis underlying the methodological approach to argument evaluation holds that some arguments which employ knowledge-gaining procedures can be suc-cessfully evaluated by applying tools elaborated by the methodology of science, such as the rules for reasoning, classifying objects, defining, and questioning. The applica-tion of those rules to argument evaluation consists in comparing them with proce-dures employed in the case of argumentative practices performed either in scientific inquiry or in everyday life. In order to show how building the methodological ap-proach (...) to argument evaluation could be started, I examine two cases of evaluating arguments by means of several methodological rules of defining. The idea of apply-ing the rules governing various knowledge-gaining procedures to evaluating argu-ments is present in philosophy of science and in argumentation theory, but so far it has not been systematically elaborated. The paper aims at justifying this idea as a promising research project. (shrink)