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.

Critical Thinking as Applied Epistemology: Relocating Critical Thinking in the Philosophical Landscape.

The phenomenon known as matching bias consists of a tendency to see cases as relevant in logical reasoning tasks when the lexical content of a case matches that of a propositional rule, normally a conditional, which applies to that case. Matching is demonstrated by use of the negations paradigm that is by using conditionals in which the presence and absence of negative components is systematically varied. The phenomenon was first published in 1972 and the present paper reviews the history of (...) research and theorising on the problem in the subsequent 25 years. Theories of matching bias considered include those based on several broad frameworks including the heuristic-analytic theory, the mental models theory, the theory of optimal data selection, and relevance theory as well as the specific processing-negations account. The ability of these theories to account for a range of phenomena is considered, including the effects of linguistic form, realistic content, and explicit negation on the matching bias effect. Of particular importance are recent findings showing that the bias is observable on a wider range of linguistic forms than has generally been thought, and that it is almost entirely dependent on the use of implicit negation in the logical cases to which rules are applied. The reasons for the general suppression of matching when realistic content is used are, however, unclear and a need for further research is identified here. It is concluded that matching bias is a highly robust effect which is closely connected with the problem of understanding implicit negation. Most of the theories in the literature are unable to account for at least some of the major phenomena discovered in research on the bias. The accounts that fare best are those that posit local effects of negation, including the heuristic-analytic and processing negations theories. (shrink)

Three experiments are reported which show that in certain contexts subjects reject instances of the valid modus ponens and modus tollens inference form in conditional arguments. For example, when a conditional premise, such as: If she meets her friend then she will go to a play, is accompanied by a conditional containing an additional requirement: If she has enough money then she will go to a play, subjects reject the inference from the categorical premise: She meets her friend, to the (...) conclusion: She will go to a play. Other contexts suppress the conditional fallacies. The first experiment demonstrates the effects of context on conditional reasoning. The second experiment shows that the inference suppression disappears when the categorical premise refers to both of the antecedents, such as: She meets her friend and she has enough money. In this case, subjects make both the valid inferences and the fallacies, regardless of the contextual information. The third experiment establishes that when subjects are given general information about the duration of a situation in which a conditional inducement was uttered, such as: If you shout then I will shoot you, they reject both the valid inferences and the fallacies. The results suggest that the interpretation of premises plays an even more central role in reasoning than has previously been admitted. Trois expériences montrent que dans certains contextes les sujets rejettent des instances valides de modus ponens et de modus tollens dans des énoncés conditionnels. Par exemple, quand une prémisse conditionnelle comme: Si elle rencontre son ami, alors elle ira jouer, est accompagnée par une phrase contenant une condition supplémentaire: Si elle a assez d'argent, alors elle ira jouer, les sujets rejettent l'inférence liant la prémisse catégorielle: Elle rencontre son ami, à la conclusion: Elle ira jouer. D'autres contextes éliminent également les inférences conditionnelles fallacieuses. La premiére expérience démontre l'effet du contexte sur la raisonnement conditionnel. La deuxiéme expérience montre que la suppression de l'inférence disparait quand la prémisse catégorielle fait référence aux deux antécédants, comme: Elle rencontre son ami et elle a assez d'argent. Dans ce cas, les sujets font aussi bien les inférences valides et fallacieuses, quelle que soit l'information contextuelle. La troisiéme expérience établit que quand l'on donne aux sujets des informations générales à propos de la durée d'une situation dans laquelle une conditionnelle a été prononcée, comme Si tu cries, alors je te tire dessus, ils rejettent autant les inférences valides que les inférences fallacieuses. Ces résultats suggèrent que l'interprétation des prémisses joue un rŏle encore plus central dans le raisonnement que l'on admettait auparavant. (shrink)

In this paper, the theory of syllogistic reasoning proposed by Johnson-Laird is shown to be inadequate and an alternative theory is put forward. Protocols of people attempting to solve syllogistic problems and explaining to another person how they reached their conclusions were obtained. Two main groups of subjects were identified. One group represented the relationship between classes in a spatial manner that was supplemented by a verbal representation. The other group used a primarily verbal representation. A detailed theory of the (...) processes for both groups is given. (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)

We argue that informal logic is epistemological. Two central questions concern premise acceptability and connection adequacy. Both may be explicated in tenns of justification, a central epistemological concept. That some premises are basic parallels a foundationalist account of basic beliefs and epistemic support. Some epistemological accounts of these concepts may advance the analysis of premise acceptability and connection adequacy. Infonnallogic has implications for other aspects of philosophy. If causal interpretations are acceptable premises and thus justified, does the world have a (...) causal structure? If evaluative premises are acceptable, i.e., justified, is value an objective feature of the world? (shrink)

: From 1902 onward, Peirce viewed esthetics, ethics, and logic as "normative sciences," interconnected spheres of philosophical inquiry that constitute his main work in value theory. The normative sciences provide the basis for a theoretical investigation of questions of value detached from practical interests. Because the normative sciences maintain Peirce's well-known insistence on realism, they set his pragmaticism apart from the more "nominalistic" pragmatism of James and Dewey. The paper aims to clarify Peirce's idea of the normative sciences, to show (...) how his realism applies in the sphere of value, and to explore his views on the proper relation between theory and practice. The concluding section suggests examples of how we might understand Peirce's rich and innovative concept of normative esthetics.Resumo: De 1902 em diante, Peirce considerava a estética, a ética e a lógica como "ciências normativas", esferas interconexas de inquirição filosófica que constituem seu principal trabalho em teoria do valor. As ciências normativas fornecem a base para uma investigação teorética de questões sobre valor independentes de interesses práticos. Porque as ciências normativas mantém a notória insistência de Peirce no realismo, elas colocam seu pragmaticismo à parte do pragmatismo mais "nominalista" de James e Dewey. O artigo almeja esclarecer a idéia de Peirce das ciências normativas, mostrar como seu realismo se aplica à esfera do valor, e explorar suas visões da própria relação entre ciência e prática. A seção concludente sugere exemplos de como podemos entender o rico e inovador conceito peirciano de estética normativa. (shrink)