The article aims to reflect on the pandemic from the situatedness of being in the eye of the storm. It discusses the contagion between biological and digital viralization, and the politics and existential effects of the pandemic non-touching.

Cet article présente une discussion sur la pensée de la mutation chez Jean-Luc Nancy, elle-même une mutation des idées philosophiques traditionnelles sur la transformation. Il entend montrer que devant le sens intransformé de transformation dans la tradition philosophique de Platon à la philosophie contemporaine, Jean-Luc Nancy ouvre une autre voie lorsqu’il comprend transformation plutôt comme touche de l’âme. Loin de soumettre la mutation à une arche-téléologie des significations, la pensée de la mutation, une pensée de la touche de l’âme, trouve (...) le sens de la mutation dans l’« en train de se faire », plutôt que dans la quête de forme et de figuration. C’est dans la mutation du sens de l’entre-deux compris comme « en train d’être », que le sens d’une mutation de sens se donne à voir dans son non-figuration. Par-là, on découvre dans la pensée de Nancy non plus un autre sens d’âme, mais comment l’âme du sens touche le monde. (shrink)

In 2015 Dag Prawitz proposed an Ecumenical system where classical and intuitionistic logic could coexist in peace. The classical logician and the intuitionistic logician would share the universal quantifier, conjunction, negation and the constant for the absurd, but they would each have their own existential quantifier, disjunction and implication, with different meanings. Prawitz’ main idea is that these different meanings are given by a semantical framework that can be accepted by both parties. The aim of the present paper is [1] (...) to prove the normalization theorem for the propositional fragment NEp of Prawitz’ ecumenical system, and [2] to show that NEp is sound and complete with respect to a Kripke-style semantics for the language of NEp. (shrink)

The relation between ex falso and disjunctive syllogism, or even the justification of ex falso based on disjunctive syllogism, is an old topic in the history of logic. This old topic reappears in contemporary logic since the introduction of minimal logic by Johansson. The disjunctive syllogism seems to be part of our general non-problematic inferential practices and superficially it does not seem to be related to or to depend on our acceptance of the frequently disputable ex falso rule. We know (...) that the acceptance of the ex falso is a sufficient condition for the acceptance of the disjunctive syllogism, but the interesting question is: is the ex falso a necessary condition for the acceptance of the disjunctive syllogism? The aim of the present paper is to discuss some possible ways to define systems that combines the preservation of the disjunctive syllogism with the rejection of the ex falso. (shrink)

Livro em homenagem ao filósofo brasileiro Luiz Henrique Lopes, um dos maiores expoentes da filosofia analítica. Neste livro grandes nomes da filosofia brasileira discorrem sobre a filosofia analítica e vários assuntos da filosofia contemporânea.

In 2015 Dag Prawitz proposed a natural deduction ecumenical system, where classical logic and intuitionistic logic are codified in the same system. In his ecumenical system, Prawitz recovers the harmony of rules, but the rules for the classical operators do not satisfy separability. In fact, the classical rules are not pure, in the sense that negation is used in the definition of the introduction and elimination rules for the classical operators. In this work we propose an ecumenical system adapting, to (...) the natural deduction framework, Girard’s mechanism of stoup. This allows for the definition of a pure harmonic natural deduction system for the propositional fragment of Prawitz’s ecumenical logic. We conclude by presenting an extension proposal to the first-order setting and a different approach to purity based on some ideas proposed by Julien Murzi. (shrink)

This collection of papers, celebrating the contributions of Swedish logician Dag Prawitz to Proof Theory, has been assembled from those presented at the Natural Deduction conference organized in Rio de Janeiro to honour his seminal research. Dag Prawitz’s work forms the basis of intuitionistic type theory and his inversion principle constitutes the foundation of most modern accounts of proof-theoretic semantics in Logic, Linguistics and Theoretical Computer Science.

This collection of papers, celebrating the contributions of Swedish logician Dag Prawitz to Proof Theory, has been assembled from those presented at the Natural Deduction conference organized in Rio de Janeiro to honour his seminal research. Dag Prawitz’s work forms the basis of intuitionistic type theory and his inversion principle constitutes the foundation of most modern accounts of proof-theoretic semantics in Logic, Linguistics and Theoretical Computer Science. The range of contributions includes material on the extension of natural deduction with higher-order (...) rules, as opposed to higher-order connectives, and a paper discussing the application of natural deduction rules to dealing with equality in predicate calculus. The volume continues with a key chapter summarizing work on the extension of the Curry-Howard isomorphism, via methods of category theory that have been successfully applied to linear logic, as well as many other contributions from highly regarded authorities. With an illustrious group of contributors addressing a wealth of topics and applications, this volume is a valuable addition to the libraries of academics in the multiple disciplines whose development has been given added scope by the methodologies supplied by natural deduction. The volume is representative of the rich and varied directions that Prawitz work has inspired in the area of natural deduction. (shrink)

Much has been said about intuitionistic and classical logical systems since Gentzen’s seminal work. Recently, Prawitz and others have been discussing how to put together Gentzen’s systems for classical and intuitionistic logic in a single unified system. We call Prawitz’ proposal the Ecumenical System, following the terminology introduced by Pereira and Rodriguez. In this work we present an Ecumenical sequent calculus, as opposed to the original natural deduction version, and state some proof theoretical properties of the system. We reason (...) that sequent calculi are more amenable to extensive investigation using the tools of proof theory, such as cut-elimination and rule invertibility, hence allowing a full analysis of the notion of Ecumenical entailment. We then present some extensions of the Ecumenical sequent system and show that interesting systems arise when restricting such calculi to specific fragments. This approach of a unified system enabling both classical and intuitionistic features sheds some light not only on the logics themselves, but also on their semantical interpretations as well as on the proof theoretical properties that can arise from combining logical systems. (shrink)

Sambin [6] proved the normalization theorem for GL, the modal logic of provability, in a sequent calculus version called by him GLS. His proof does not take into account the concept of reduction, commonly used in normalization proofs. Bellini [1], on the other hand, gave a normalization proof for GL using reductions. Indeed, Sambin's proof is a decision procedure which builds cut-free proofs. In this work we formalize this procedure as a recursive function and prove its recursiveness in an arithmetically (...) formalizable way, concluding that the normalization of GL can be formalized in PA. MSC: 03F05, 03B35, 03B45. (shrink)

Recent works about ecumenical systems, where connectives from classical and intuitionistic logics can co-exist in peace, warmed the discussion on proof systems for combining logics. This discussion has been extended to alethic modalities using Simpson’s meta-logical characterization: necessity is independent of the viewer, while possibility can be either intuitionistic or classical. In this work, we propose a pure, label free calculus for ecumenical modalities, nEK\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathsf {nEK}$$\end{document}, where exactly one logical operator figures (...) in introduction rules and every basic object of the calculus can be read as a formula in the language of the ecumenical modal logic EK\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathsf {EK}$$\end{document}. We prove that nEK\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathsf {nEK}$$\end{document} is sound and complete w.r.t. the ecumenical birelational semantics and discuss fragments and extensions. (shrink)

Sambin [6] proved the normalization theorem for GL, the modal logic of provability, in a sequent calculus version called by him GLS. His proof does not take into account the concept of reduction, commonly used in normalization proofs. Bellini [1], on the other hand, gave a normalization proof for GL using reductions. Indeed, Sambin's proof is a decision procedure which builds cut-free proofs. In this work we formalize this procedure as a recursive function and prove its recursiveness in an arithmetically (...) formalizable way, concluding that the normalization of GL can be formalized in PA. MSC: 03F05, 03B35, 03B45. (shrink)

This paper deals with the recent Swedish proposals of a Intuitionistic notion of Truth, by Dag Prawitz and Per Martin-Löf.

Proceedings of the Tenth Brazilian Conference on Mathematical Logic. Coleção CLE, volume 14, 1995. Centro De Lógica, Epistemologia e História da Ciência, Unicamp, Campinas, SP, Brazil.

Abstract:Pedro Erber and Facundo Vega speak with Marcia Sá Cavalcante Schuback about Heidegger's influence on philosophy in Brazil and beyond.

This paper proposes a classification of economic models into three types: historical, axiomatic and conditional. Historical or empirical models utilize the historical-deductive method, and are generalizations from the economic regularities and tendencies that we find in the real world. Axiomatic models utilize the hypothetical-deductive method; they are syllogisms whose major premise is an axiom – a self-evident truth; they are appropriate for methodological sciences such as mathematics and econometrics. Conditional economic models are likewise syllogisms, but they are suitable for economics (...) because they make for clearer and more precise economic reasoning. The criterion of truth of the substantive sciences is the conformity with reality, of the methodological science, its internal consistency. When a school of economic thought adopts mainly axiomatic models, as is the case with neoclassical economics, it implicitly falls into contradiction because their best representatives believe in the conformity with reality criterion. (shrink)

In 1930, Johann von Neumann, together with Rudolf Carnap and Arend Heyting, participated in a conference held in Königsberg, called “Second Seminar on the Epistemology of Exact Sciences”. The idea behind the reunion of these three researchers was to compose a fairly faithful picture of the three main foundational programs of mathematics at the time: formalism, logicism, and intuitionism. The main objective of this paper is to propose an analysis of the text “The Formalist Foundation of Mathematics” presented by von (...) Neumann in this conference. We show how, from von Neumann's perspective, the problem of the consistency of mathematical theories results from the transformation of a genuinely philosophical question into a genuinely logical-mathematical question and how a proof of consistency could be seen as the solution to the foundational problem. In the final part of the text, we present some considerations about Gerhard Gentzen’s consistency proofs and their importance to contemporary proof theory. (shrink)

A lógica não contém teoremas puramente existenciais: as únicas sentenças existenciaisválidas são aquelas com análogas universais válidas. Aqui, mostramos que istorealmente é assim quando corretamente interpretado: toda validade ex- istencial possuiuma análoga universal simples, que também é válida. Também caracterizamos validadesuniversais e existenciais em termos de tautologias.

Veloso-Pereira-Haeusler_On-what-there-must-be.

Coletânea de artigos em homenagem a Guido Antonio de Almeida e Raul Ferreira Landim Filho.

Omnipresent in popular culture, especially in film and literature, the theme of the 'end of the world' is often rejected from contemporary philosophy as hysterical apocalyptism. This volume attempts to show that it is vital that we address the motif of the 'end' in contemporary world – but that this cannot be done without thinking it anew.

This book is a philosophical reflection on the experience of time from within exile. Its focus on temporality is unique, as most literature on exile focuses on the experience of space, as exile involves dislocation, and moods of nostalgia and utopia. Marcia Sá Cavalcante Schuback proposes that in exile, time is experienced neither as longing back to the lost past nor as wanting a future to come but rather as a present without anchors or supports. She articulates (...) this present as a "gerundive" mode, in which the one who is in exile discovers herself simply being, exposed to the uncanny experience of having lost the past and not having a future. To investigate this, the book establishes a conversation among three authors whose work has exemplified this sense of gerundive time: the German philosopher Martin Heidegger, the French writer and essayist Maurice Blanchot, and the Brazilian writer Clarice Lispector. The book does not aim to discuss how these authors understand the relation between time and exile but enters in conversation with them in relation to this question. Attempting to think and express this difficult sense of time from within exile, the book engages with the relation between thought and language, and between philosophy and literature. Departing from concrete existential questions, it opens new philosophical and theoretical modes through which to understand what it means to be present in times of exile. (shrink)

Teknikens skugga -- Ett sublimt mellan -- Tiden i formen -- Fenomenets blick -- Om bild -- Tolkningsfigurer -- Abstraktioner -- Anteckningar -- Det omåttligas måleri -- Att tänka i skisser.

This article discusses Alejandro Vallega’s book, Latin American Philosophy: From Identity to Radical Exteriority, proposing a series of questions in which the problem of situating Latin American thought in the topos of Western philosophy is addressed. Further questions considered here include how to rethink identity and difference from the perspective of Latin American experience, and, last but not least, what do “situated thinking” and “engaged thought” mean?

This book is a philosophical reflection on the experience of time from within exile. Its focus on temporality is unique, as most literature on exile focuses on the experience of space, as exile involves dislocation, and moods of nostalgia and utopia. Marcia Sá Cavalcante Schuback proposes that in exile, time is experienced neither as longing back to the lost past nor as wanting a future to come but rather as a present without anchors or supports. She articulates (...) this present as a "gerundive" mode, in which the one who is in exile discovers herself simply being, exposed to the uncanny experience of having lost the past and not having a future. To explore this, she establishes a conversation among three authors whose work has exemplified this sense of gerundive time: the German philosopher Martin Heidegger, the French writer and essayist Maurice Blanchot, and the Brazilian writer Clarice Lispector. The book does not aim to discuss how these authors understand the relation between time and exile, but presents a conversation with them in relation to this question that reflects new aspects in their work. Attempting to think and express this difficult sense of time from within exile, Time in Exile engages with the relation between thought and language, and between philosophy and literature. Departing from concrete existential questions, Sá Cavalcante Schuback reveals new philosophical and theoretical modes to understand what it means to be present in times of exile. (shrink)

In this article I argue not only for the value of hermeneutics today but also, and especially, how the crucial gesture of hermeneutics is that of changing the subject for the sake of our today. Surveying briefly the main lines of hermeneutical positions along its history and critiques, and connecting these critiques to the discrepancy between theory and practice, between interpretation and the need to change the world, the article proposes that our reality today, reshaped through globalization and the virtual, (...) is performed as a hermeneutics of history. The challenge for today’s hermeneutics is to work out categories for understanding the present as on-going in a world that tends to capture and distort more and more the meaning of freedom of thought. In the final section, I propose a hermeneutics of the on-going, of gerundive time, partially under the inspiration of Paul Celan, as a response that develops the meaning of the freedom of thought. A defense of nearness and how to think in narrow nearness to the on-going is discussed. (shrink)

The present text discusses the problems concerning the translation and the non- translation of the thinking word Dasein in Sein und Zeit. Assuming that for Heidegger Dasein is transcendence and this as an in-finitive trans-lation from a substantive and substantial meaning of being to a verbal one, it becomes necessary to translate the word Dasein in Sein und Zeit above all within the German language itself. The task of translating the thinking word Dasein is therefore the one of making possible (...) the work of thought in which the destruction of the substantialistic meaning of being can take place always anew. Showing the verbal temporality of the thinking word Dasein as the internal and aspectual temporality of a Währenden, the article explains the translating choices made in my translation of Sein und Zeit into Portuguese. (shrink)

This article presents Clarice Lispector’s view on writing, showing that for her literature is the writing of the act of writing itself. In question is the writing of the act while acting, the is-being of existence. In this sense, Lispector described her writing as the writing of a screaming object, as abstract writing, almost a painting. Following some central passages of different works, the article is an attempt to seize the main traits of what could be called the gerundive act (...) of literature of Clarice Lispector. (shrink)

This is an edited collection of original essays that combine philosophy, phenomenology, and literature to reflect on modern ideas about orientation and disorientation, grounds and groundlessness.

On lira ici un dialogue qui ne s’est donné ni règles préliminaires de progression ni aboutissement calculé d’avance, mais qui s’est inventé au fur et à mesure de son avancée. L’intention initiale était d’examiner ce que Heidegger nomme « la traduction occidentale » dans La parole d’Anaximandre : d’une part, que veut dire « traduction » là où l’on se guide sur des « traces » dont la nature même, comme traces, est problématique? D’autre part, comment comprendre le Brauch qui (...) porte la charge finale de cette « traduction »? En arrière-plan surgit la question : quelle est donc l’histoire dont Heidegger se réclame? (shrink)