In this paper, a family of paraconsistent propositional logics with constructive negation, constructive implication, and constructive co-implication is introduced. Although some fragments of these logics are known from the literature and although these logics emerge quite naturally, it seems that none of them has been considered so far. A relational possible worlds semantics as well as sound and complete display sequent calculi for the logics under consideration are presented.

This paper deals with various substructural propositional logics, in particular with substructural subsystems of Nelson's constructive propositional logics N– and N. Doen's groupoid semantics is extended to these constructive systems and is provided with an informational interpretation in terms of information pieces and operations on information pieces.

The paper provides a uniform Gentzen-style proof-theoretic framework for various subsystems of classical predicate logic. In particular, predicate logics obtained by adopting van Behthem''s modal perspective on first-order logic are considered. The Gentzen systems for these logics augment Belnap''s display logic by introduction rules for the existential and the universal quantifier. These rules for x and x are analogous to the display introduction rules for the modal operators and and do not themselves allow the Barcan formula or its converse to (...) be derived. En route from the minimal modal predicate logic to full first-order logic, axiomatic extensions are captured by purely structural sequent rules. (shrink)

Betr. u.a. die letzten Briefe Friedrich Nietzsches an Jacob Burckhardt.

A version of strong negation is introduced into Categorial Grammar. The resulting syntactic calculi turn out to be systems of connexive logic.

This volume is dedicated to Prof. Dag Prawitz and his outstanding contributions to philosophical and mathematical logic. Prawitz's eminent contributions to structural proof theory, or general proof theory, as he calls it, and inference-based meaning theories have been extremely influential in the development of modern proof theory and anti-realistic semantics. In particular, Prawitz is the main author on natural deduction in addition to Gerhard Gentzen, who defined natural deduction in his PhD thesis published in 1934. The book opens with an (...) introductory paper that surveys Prawitz's numerous contributions to proof theory and proof-theoretic semantics and puts his work into a somewhat broader perspective, both historically and systematically. Chapters include either in-depth studies of certain aspects of Dag Prawitz's work or address open research problems that are concerned with core issues in structural proof theory and range from philosophical essays to papers of a mathematical nature. Investigations into the necessity of thought and the theory of grounds and computational justifications as well as an examination of Prawitz's conception of the validity of inferences in the light of three “dogmas of proof-theoretic semantics” are included. More formal papers deal with the constructive behaviour of fragments of classical logic and fragments of the modal logic S4 among other topics. In addition, there are chapters about inversion principles, normalization of p roofs, and the notion of proof-theoretic harmony and other areas of a more mathematical persuasion. Dag Prawitz also writes a chapter in which he explains his current views on the epistemic dimension of proofs and addresses the question why some inferences succeed in conferring evidence on their conclusions when applied to premises for which one already possesses evidence. (shrink)

Paru en 1909 dans les Kant-Studien, « Les deux voies de la théorie de la connaissance » constitue une pièce maîtresse du débat qui opposa le néokantisme à la phénoménologie naissante. Heinrich Rickert, qui fut avec Windelband et Lask l’un des principaux représentants de l’école néokantienne de Heidelberg, y expose de façon claire et synthétique les principes méthodiques qui fondent sa philosophie critique. À travers un dialogue constant avec les Recherches logiques de Husserl, Rickert distingue deux « voies » (...) ou deux méthodes que peut suivre la théorie de la connaissance : la méthode psychologico-transcendantale , correspondant à l’analyse de l’acte de juger, et la méthode logico-transcendantale , correspondant à l’analyse du sens propositionnel. Comment ces deux méthodes s’articulent-elles? Quelle est leur contribution propre au programme critique? Et quelles sont leurs limites respectives? Sur ces questions, la position de Rickert se révèle aussi riche et innovante que celle de Husserl, dont elle diffère sensiblement. L’aspect à la fois polémique et concis de ce texte en fait un document essentiel pour la connaissance de l’école de Heidelberg et, plus généralement, pour l’étude du néokantisme dans son ensemble. (shrink)