Cette édition numérique a été réalisée à partir d'un support physique, parfois ancien, conservé au sein du dépôt légal de la Bibliothèque nationale de France, conformément à la loi n° 2012-287 du 1er mars 2012 relative à l'exploitation des Livres indisponibles du XXe siècle. Pages de début Avertissement Les paradoxes logiques Première partie - Signification et dénotation Les expressions simplement significatives et une catégorie d'expressions dénotatives : les descriptions définies Autres catégories d'expressions dénotatives L'élimination des expressions dénotatives Seconde partie - (...) Prédicativité et universalité Le principe du cercle vicieux La théorie substitutionnelle La théorie des types Unecertaine idée de la logique Références bibliographiques Pages de fin. (shrink)

Van Heijenoort’s main contribution to history and philosophy of modern logic was his distinction between two basic views of logic, first, the absolutist, or universalist, view of the founding fathers, Frege, Peano, and Russell, which dominated the first, classical period of history of modern logic, and, second, the relativist, or model-theoretic, view, inherited from Boole, Schröder, and Löwenheim, which has dominated the second, contemporary period of that history. In my paper, I present the man Jean van Heijenoort (Sect. 1); then (...) I describe his way of arguing for the second view (Sect. 2); and finally I come down in favor of the first view (Sect. 3). There, I specify the version of universalism for which I am prepared to argue (Sect. 3, introduction). Choosing ZFC to play the part of universal, logical (in a nowadays forgotten sense) system, I show, through an example, how the usual model theory can be naturally given its proper place, from the universalist point of view, in the logical framework of ZFC; I outline another, not rival but complementary, semantics for admissible extensions of ZFC in the very same logical framework; I propose a way to get universalism out of the predicaments in which universalists themselves believed it to be (Sect. 3.1). Thus, if universalists of the classical period did not, in fact, construct these semantics, it was not that their universalism forbade them, in principle, to do so. The historical defeat of universalism was not technical in character. Neither was it philosophical. Indeed, it was hardly more than the victory of technicism over the very possibility of a philosophical dispute (Sect. 3.2). (shrink)

Is second-order quantification legitimate? For Quine, it was pure non-sense, unless construed as first-order quantification in disguise, ranging over sets. Boolos rightly maintained that it could be interpreted in terms of plural quantification, but claimed that it then ranged over the same individuals as singular, first-order quantification. I protest that plural quantification ranges over what I call multiplicities. But what is a 'multiplicity'? And does this idea itself not fall prey to something like Frege's paradox?

Na gruncie myśli współczesnej próbowano określić pojęcie wynikania logicznie poprawnego. Odsyła to do pojęcia form (logicznych) wypowiedzi logicznie prawdziwych, a więc do formuł tautologicznych. W dyskusji na ten temat jedno ze stanowisk ma charakter syntaktyczny i zewnętrzny (Frege, Russell), inna ma charakter semantyczny i wewnętrzny. Formuła tautologiczna to z definicji formuła prawdziwa dla wszystkich interpretacji liter schematycznych. Jak rozumieć pojęcie "wszystkie interpretacje”? Istnieje w tym względzie kilka propozycji; jedna z nich pochodzi od Tarskiego, inna od Hilberta i Ackermanna. Pokazując, dlaczego (...) te definicje są niewystarczające, autor traktuje problem jako otwarty. (shrink)

Is IF logic the true elementary logic, as Hintikka claims? Moreover is it truly elementary, viz. first-order, in the first place? One is tempted to answer no, because of the extraordinary power of this logic in comparison with ordinary first-order logic. However impressive this objection may be, it misses its aim. A direct refutation is needed, grounded on an analysis of the notion of order.RésuméLa logique IF est-elle la véritable logique élémentaire, comme le prétend Hintikka ? Mais, d’abord, est-elle véritablement (...) élémentaire, c’est-à-dire du premier ordre ? Il est tentant de répondre non, en arguant du pouvoir extraordinaire de cette logique par rapport à la logique du premier ordre ordinaire. Mais, pour impressionnante que puisse être l’objection, elle n’atteint pas son but. Il faut une réfutation directe, fondée sur l’analyse de la notion d’ordre. (shrink)

For the sake of simplicity, we adopt the same logical frame as Tarski's in his Wahrheitsbegriff (Wb). There, Tarski is mainly interested in the possibility of explicitely defining truth for an object-language, he does not pay much attention to recursive definitions of truth. We say why. However, recursive definitions have advantages of their own. In particular, we prove the positive theorem: if L is of finite order ≥ 4, then a recursive definition is possible for L in a metalanguage of (...) the same order as L. We indicate how this result could be used for a solution of a generalized version of Frege's paradox. (shrink)