Un libro de texto de lógica, argumentación y razonamiento probabilístico que he estado escribiendo durante los últimos años. Lo he usado para clases en bachillerato, licenciatura y posgrado. Está incompleto todavía, pero las primeras tres partes (argumentación, lógica proposicional, y cuantificación) están completas a un 85%, aproximadamente. Si lo usas, me ayudarías mucho mandándome comentarios, críticas y cualquier sugerencia.

The purpose of this introduction is to give a rough overview of the discussion of the formalization of arguments, focusing on deductive arguments. The discussion is structured around four important junctions: i) the notion of support, which captures the relation between the conclusion and premises of an argument, ii) the choice of a formal language into which the argument is translated in order to make it amenable to evaluation via formal methods, iii) the question of quality criteria for such formalizations, (...) and finally iv) the choice of the underlying logic. This introductory discussion is supplemented by a brief description of the genesis of the special issue, acknowledgements, and summaries of each article. (shrink)

An introduction to philosophy of language since Frege, focusing on the 20th century.

It is no accident that we begin this article with a quotation from Marek Tokarz. His article entitled Komunikacja poza gramatyką [eng. Communication beyond grammar], which was published in the commemorative book in honor of professor Jerzy Pelc W świecie znaków: księga pamiątkowa ku czci profesora Jerzego Pelca, was one of the chief inspirations for this paper. In his article, Tokarz studied the possibility of achieving communication without syntax. In what follows, we intend to go one step further and analyze (...) the possibility of achieving communication without verbal means. Let us begin with specifying the term ’nonverbal communication’. According to the common definition, it is a communication which involves giving signs other than words. Verbal communication is not identified with oral, spoken communication, but with a communication established through words. That is why emitting sounds such as muttering or humming are considered nonverbal messages. On the other hand, sign language and written language are treated as verbal communication. (shrink)

This chapter introduces and discusses the concepts of necessary and sufficient conditions.

Argument evaluation, one of the central problems in argumentation theory, consists in studying what makes an argument a good one. This paper proposes a formal approach to argument evaluation from the perspective of justification logic. We adopt a multi-agent setting, accepting the intuitive idea that arguments are always evaluated by someone. Two general restrictions are imposed on our analysis: non-deductive arguments are left out and the goal of argument evaluation is fixed: supporting a given proposition. Methodologically, our approach uses several (...) existing tools borrowed from justification logic, awareness logic, doxastic logic and logics for belief dependence. We start by introducing a basic logic for argument evaluation, where a list of argumentative and doxastic notions can be expressed. Later on, we discuss how to capture the mentioned form of argument evaluation by defining a preference operator in the object language. The intuitive picture behind this definition is that, when assessing a couple of arguments, the agent puts them to a test consisting of several criteria. As a result of this process, a preference relation among the evaluated arguments is established by the agent. After showing that this operator suffers a special form of logical omniscience, called preferential omniscience, we discuss how to define an explicit version of it, more suitable to deal with non-ideal agents. The present work exploits the formal notion of awareness in order to model several informal phenomena: awareness of sentences, availability of arguments and communication between agents and external sources. We discuss several extensions of the basic logic and offer completeness and decidability results for all of them. (shrink)

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)

This paper presents a way in which formal logic can be understood and reformulated in terms of argumentation that can help us unify formal and informal reasoning. Classical deductive reasoning will be expressed entirely in terms of notions and concepts from argumentation so that formal logical entailment is equivalently captured via the arguments that win between those supporting concluding formulae and arguments supporting contradictory formulae. This allows us to go beyond Classical Logic and smoothly connect it with human reasoning, thus (...) providing a uniform argumentation-based view of both informal and formal logic. (shrink)

Some have suggested that images can be arguments. Images can certainly bolster the acceptability of individual premises. We worry, though, that the static nature of images prevents them from ever playing a genuinely argumentative role. To show this, we call attention to a dilemma. The conclusion of a visual argument will either be explicit or implicit. If a visual argument includes its conclusion, then that conclusion must be demarcated from the premise or otherwise the argument will beg the question. If (...) a visual argument does not include its conclusion, then the premises on display must license that specific conclusion and not its opposite, in accordance with some demonstrable rationale. We show how major examples from the literature fail to escape this dilemma. Drawing inspiration from the graphical logic of C. S. Peirce, we suggest instead that images can be manipulated in a way that overcomes the dilemma. Diagrammatic reasoning can take one stepwise from an initial visual layout to a conclusion—thereby providing a principled rationale that bars opposite conclusions—and the visual inscription of this correct conclusion can come afterward in time—thereby distinguishing the conclusion from the premises. Even though this practical application of Peirce’s logical ideas to informal contexts requires that one make adjustments, we believe it points to a dynamic conception of visual argumentation that will prove more fertile in the long run. (shrink)

This article provides a brief selective overview and discussion of recent research into natural language argumentation that may inform the study of human reasoning on the assumption that an episode of argumentation issues an invitation to accept a corresponding inference. As this research shows, arguers typically seek to establish new consequences based on prior information. And they typically do so vis-à-vis a real or an imagined opponent, or an opponent-position, in ways that remain sensitive to considerations of context, audiences, and (...) goals. Deductively valid inferences remain a limiting case of such reasoning. In view of these insights, it may appear less surprising that allegedly “irrational” behavior can regularly be produced in experimental settings that expose subjects to standardized reasoning tasks. (shrink)

In the paper the following questions are discussed: What is logical consequence? What are logical constants? What is a logical system? What is logical pluralism? What is logic? In the conclusion, the main tendencies of development of modern logic are pointed out.

I consider several outstanding questions about analogies. These include the following: issues of interpretation especially with regard to whether an analogy should be considered argumentative, as distinct from serving as an illustration, explanation, or matter of rhetorical interest; whether and how to draw a distinction between inductive analogies and a priori analogies; and whether a priori analogies should be reconstructed as deductively valid arguments. The discussion will explore broader themes such as the distinction between the a priori and the deductive, (...) and whether a priori analogies offer reasons for a choice, as distinct from a basis for inferring an inference. Referring to the recent work of Harald Wolhrapp, I will explore the allegation that a faulty logicism is involved when argument analysis is based on an explicit statement of premises and conclusion. In developing this account, reference will also be made to the work of Douglas Walton, Marcello Guarini, Trudy Govier, and Lilian Bermejo-Luque. (shrink)

In this paper, I will try to answer the question: How are we supposed to assess the expert’s opinion in an argument from the position of an outsider to the specialized field? by placing it in the larger context of the political status of epistemic authority. In order to do this I will first sketch the actual debate around the problem of expertise in a democracy and relate this to the issue of the status of science in society. Secondly, I (...) will review how Douglas Walton’s pragma-dialectical approach offers a practical procedure to assess the expert bias from a nonprofessional’s perspective. Thirdly, I will introduce the problem of group bias using insights from Bohman and Fischer and show how Walton’s solution does not address this specific type of bias. Lastly, I will try proposing a revision of Walton’s solution in order to address this problem. In order to make the explanation more easy to follow I will use a case study concerning the medical expertise in the public debate on second-hand smoke. (shrink)

This volume presents a selection of papers reflecting key theoretical issues in argumentation theory. Its six sections are devoted to specific themes, including the analysis and evaluation of argumentation, argument schemes and the contextual embedding of argumentation. The section on general perspectives on argumentation discusses the trends of empiricalization, contextualization and formalization, offers descriptions of the analytical and evaluative tools of informal logic, and highlights selected principles that argumentation theorists do and do not agree upon. In turn, the section on (...) linguistic approaches to argumentation focuses on the problem of distinguishing between explanation and argument, while also elaborating on the role of verbal indicators of argument schemes. All essays included in this volume point out notable recent developments in the study of argumentation. (shrink)

When an activity is unwanted, administrators often adopt a zero tolerance policy towards that activity. The background assumption is that, by adopting a zero tolerance policy, one is doing everything that one can to reduce or eliminate the activity in question. Yet which policy best serves to reduce an unwanted behavior is always an empirical question. Thus, those who adopt a zero tolerance policy towards some behavior without first investigating and finding that they are in a set of circumstances where (...) that policy is the most cost-effective way of reducing or eliminating the undesirable behavior are committing the zero tolerance fallacy. (shrink)

The zero tolerance fallacy occurs when someone advocates or adopts a zero tolerance policy towards some activity or behaviour without seeing if there is evidence to support the view that such a policy is the best or most cost-effective way of preventing or reducing the unwanted behaviour. This paper explores the idea that, instead of thinking about what the zero tolerance fallacy is, argumentation theorists should try to characterize what features good arguments for zero tolerance policies must have.

The paper emphasizes significant resemblances between the Informal Logic Initiative and the Lvov-Warsaw School – the Polish philosophical movement, the rise of which is associated with “the Golden Age of Science and Letters”. The correspondence between informal logic and the logical studies of the LWS will be explored by discussing their subject-matter, goals, and methods. The project focused on applying logical studies of the LWS in analyzing and assessing arguments will be proposed.

We argue that Hilary Putnam's pragmatism provides an epistemological perspective which can help us understand--and can positively inform--the development of informal logic.

Abstract In this essay, I will argue that images can play a substantial role in argumentation: exploiting information from the context, they can contribute directly and substantially to the communication of the propositions that play the roles of premises and conclusion. Furthermore, they can achieve this directly, i.e. without the need of verbalization. I will ground this claim by presenting and analyzing some arguments where images are essential to the argumentation process. Content Type Journal Article Pages 1-14 DOI 10.1007/s10503-011-9259-y Authors (...) Axel Arturo Barceló Aspeitia, Instituto de Investigaciones Filosóficas, Universidad Nacional Autónoma de México, Cto. Mario de la Cueva s/n, Cd. Universitaria, Coyoacán, 04500 DF, Mexico Journal Argumentation Online ISSN 1572-8374 Print ISSN 0920-427X. (shrink)

In this paper, we will explore two initiatives that focus on the importance of employing logical theories in educating people how to think and reason properly, one in Poland: The Lvov-Warsaw School; the other in North America: The Informal Logic Initiative. These two movements differ in the logical means and skills that they focus on. However, we believe that they share a common purpose: to educate students in logic and reasoning (logical education conceived as a process) so that they may (...) be able to apply their skills to analyze the issues in their society (logical culture as a result of logical education). The aim of the paper is to justify this claim by exploring research objectives and products that are common to both movements. (shrink)

Pragmatics and dialectics are two disciplines which have been amongst the first and most important partners for argument studies in the exploration of the complex realm of communication. Treating argumentation as a construct consisting of premises and conclusion allows for investigating some interesting properties of the phenomenon of reasoning, but does not capture a variety of aspects related to the usage of natural language and dialogical context in which real-life argumentation is typically embedded. This special issue explores some of the (...) fascinating research questions which emerge when we move beyond logic into the territory of the pragmatics and dialectics of argument. (shrink)

In this paper, I argue that arguments from expert opinion, i.e., inferences from “Expert E says that p” to “p,” where the truth value of p is unknown, are weak arguments. A weak argument is an argument in which the premises, even if true, provide weak support—or no support at all—for the conclusion. Such arguments from expert opinion are weak arguments unless the fact that an expert says that p makes p significantly more likely to be true. However, research on (...) expertise shows that expert opinions are only slightly more accurate than chance and much less accurate than decision procedures. If this is correct, then it follows that arguments from expert opinion are weak arguments. (shrink)

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 general goal is to encourage informal logicians and those interested in applied epistemology to look at epidemiology as a paradigmatic science crucially dependant on argumentation to justify its claims. Three specific goals are: 1. exemplify applied epistemology by looking critically at causal argumentation in epidemiology, 2. show that justification of causal claims in epidemiology is a form of “argument to the best explanation,” 3. show that there could be a symbiotic relationship between epidemiology and work in various applied reasoning (...) disciplines such as argumentation and “applied epistemology.”. (shrink)

In the last quarter-century, the emergence of argumentation theory has spurred the development of an extensive literature on the study of argument. It encompasses empirical and theoretical investigations that often have their roots in the different traditions that have studied argument since ancient times – most notably, logic, rhetoric, and dialectics. Against this background, I advocate a “thick” theory of argument that merges traditional theories, weaving together their sometimes discordant approaches to provide an overarching framework for the assessment of arguments (...) in a broad range of contexts. In sketching such a theory, I propose six steps that can “thicken” traditional approaches to argument in the interests of a comprehensive theory. (shrink)

In a posthumous paper, Perelman discusses his decision to bring his theory of argumentation together with rhetoric rather than calling it an informal logic. This is due in part because of the centrality he gives to audience, and in part because of the negative attitude that informal logicians have to rhetoric. In this paper, I explore both of these concerns by way of considering what benefits Perelman’s work can have for informal logic, and what insights the work of informal logicians (...) might bring to the project of Perelman and Olbrechts-Tyteca. (shrink)

Building on our diverse research traditions in the study of reasoning, language and communication, the Polish School of Argumentation integrates various disciplines and institutions across Poland in which scholars are dedicated to understanding the phenomenon of the force of argument. Our primary goal is to craft a methodological programme and establish organisational infrastructure: this is the first key step in facilitating and fostering our research movement, which joins people with a common research focus, complementary skills and an enthusiasm to work (...) together. This statement—the Manifesto—lays the foundations for the research programme of the Polish School of Argumentation. (shrink)

Fugue and chaos are used in their contemporary meaning. Elements of the fugue, albeit a ‎small number of universals, will be demonstrated in the area of visual and verbal colors. ‎Chaos dominates the internet, fashion, and everyday life. The visual and verbal colors are ‎differentiated and their communicative potential is indicated alongside the diachronic changes. The prototypes of colors are the interface between visual and verbal colors.‎.

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)

This paper will describe what happened to the community of informal logicians between 1983 and 1987, when they started to interact with communication scholars, rhetoricians and Pragma-Dialecticians. Special attention will be paid to key events, such as the Second International Symposiums on Informal Logic, the founding of AILACT in 1983, the start of journal Informal logic in 1984, and the international conference on argumentation held at Amsterdam in 1986.

The article aims to develop an analysis of the construction of political propagandist speech. We will approach the advertising speech from the perspective of the visual semiotics’ particularities. We will consider the theory of consensual truth, proposing a constructionist theory of the discursive truth, highlighting a particularity of the social construction of the truth – exercising the consensus trance as an instrument of visual semiotics.