À quelles conditions peut-on, dans un discours réel, utiliser un énoncé comme argument en faveur d’un autre? La réponse semble aller de soi, au moins si l’on assimile l’argumentation à une espèce de raisonnement - peut-être lâche et flou, mais analogue en son fond à la démonstration étudiée par les logiciens. Dans ce cas, l’enchaînement des énoncés se fonde sur les informations qu’ils véhiculent, sur ce qu’ils disent de la réalité. C’est justement l’inverse que veut montrer la théorie des échelles (...) argumentatives. Selon elle, la structure des énoncés, au sens le plus étroitement grammatical du terme, contient, indépendamment des informations qu’ils donnent, des indications sur le type de conclusions qu’ils peuvent servir. Le sens même de nos paroles doit alors être vu comme étant, de façon intrinsèque, un moyen pour orienter le discours de l’autre, l’intention de dire ne se distinguant pas de l’intention de faire dire. Ce qui fait triompher le structuralisme là où on l’attend le moins, en sémantique - la valeur sémantique d’un énoncé est constituée par allusion à la possibilité d’un autre énoncé - l’énoncé de l’autre. (shrink)

'Is there any other point to which you would wish to draw my attention?' 'To the curious incident of the dog in the night-time.' 'The dog did nothing in the night-time.' 'That was the curious incident, ' remarked Sherlock Holmes. The quotation from A. Conan Doyle with which this book begins, is a delightfully appropriate summation of the authors' point of view garnered from their fifteen years of experiments on the psychology of reasoning. Dr. Wason and Dr. Johnson-Laird are intrigued (...) by the extent to which most individuals can be considered naturally rational thinkers. They present here the surprising results of their comprehensive investigations of how humans draw explicit conclusions from evidence. Given a set of assertions, the authors write, to what extent can the individual appreciate all that follows from them by virtue of logic alone, and remain unseduced by plausible, but fallacious conclusions? We are not concerned with whether these assertions are true or false, nor with whether the individual holds them among his beliefs, nor with whether they are sane or silly. At the core of the Psychology of Reasoning is a vigorous discussion that incorporates various illustrations--some of them humorous, all of them fascinating--of the use of reason under a wide variety of different conditions. Particular emphasis is placed on the difficulties involved in dealing with negatively marked information that must be combined and used with other information for reaching conclusions. Thorough treatment is given as well to the search for plausible contexts that will render anomalous or ambiguous statements sensible. The authors have strived to isolate the components ofinference, the basic steps of any kind of deductive activity, in order to determine the psychological processes involved in them. What has been the outcome of this research? Dr. Wason and Dr. Johnson-Laird conclude, our research has suggested that the individual's logical competence may be either enhanced or limited by performance variables. And, of these, content has turned out to be vitally important for revealing, or obscuring structure. At best, we can all think like logicians; at worst, logicians all think like us. (shrink)

It is well known that classical logics are able to represent only some aspects of ordinary reasoning. In particular, by accepting the law of obversion, they remove the possibility of defining any but a propositional negation; certain natural uses of negation thus elude them. Logical theories do exist, however, that are exempt from such limitations. Among these theories are those of S. Leśniewski, which differ profoundly from classical formal systems. Unlike the latter, they do not have a determined list of (...) functors of syntactical-semantical categories. Due to formalized directives for definitions, the logics of Leśniewski are constructed progressively, making new theses and consequently functors of new syntactical-semantical categories accessible. In this article we use some of these theses-definitions to define a principle of appropriateness. With this principle it is possible to represent certain logical subtleties that are used quite naturally but are neglected due to the law of obversion. (shrink)