This paper examines to what extent Davidsonian truth-theoretic semantics can give an adequate account for empty names in natural languages. It argues that the prospect is dim because of a tension between metaphysical austerity, non-vacuousness of theorems and empirical adequacy. Sainsbury (2005) proposed a Davidsonian account of empty names called ‘Reference Without Referents’ (RWR), which explicates reference in terms of reference-condition rather than referent, thus avoiding the issue of existence. This is an inspiring account. However, it meets several difficulties. First, (...) there is no non-vacuous, interpretive truth-condition available for any T-sentence containing an empty name, because by stipulation there is no way to compose a true atomic sentence using an empty name in RWR. The absence of an interpretive truth-condition implies the absence of an interpretive reference-condition. It also entails empirical inadequacy to support an interpretation because the related propositional attitude can never be truly satisfied. These considerations cast doubt on whether truth is the proper vehicle to articulate meaning. This paper suggests that we can alleviating the problem by employing truth-conditions varying across contexts of utterance, rather than just contexts of evaluation. The result is a two-dimensional model-theoretic approach to empty names. It involves a new function coined counterfactual reference and the account is compatible with both descriptivism and Millianism. (shrink)

This book provides a detailed exposition of one of the most practical and popular methods of proving theorems in logic, called Natural Deduction. It is presented both historically and systematically. Also some combinations with other known proof methods are explored. The initial part of the book deals with Classical Logic, whereas the rest is concerned with systems for several forms of Modal Logics, one of the most important branches of modern logic, which has wide applicability.

Este livro marca o início da Série Investigação Filosófica. Uma série de livros de traduções de textos de plataformas internacionalmente reconhecidas, que possa servir tanto como material didático para os professores das diferentes subáreas e níveis da Filosofia quanto como material de estudo para o desenvolvimento pesquisas relevantes na área. Nós, professores, sabemos o quão difícil é encontrar bons materiais em português para indicarmos. E há uma certa deficiência na graduação brasileira de filosofia, principalmente em localizações menos favorecidas, com relação (...) ao conhecimento de outras línguas, como o inglês e o francês. Tentamos, então, suprir essa deficiência, ao introduzirmos traduções de textos importantes ao público de língua portuguesa, sem nenhuma finalidade comercial e meramente pela glória da filosofia. O presente volume é constituído de três traduções de verbetes importantes sobre lógica, da Enciclopédia de Filosofia da Stanford: (1) A Lógica de Aristóteles, (2) Lógica Clássica, (3) Lógica Modal. (shrink)

Esta enciclopédia abrange, de uma forma introdutória mas desejavelmente rigorosa, uma diversidade de conceitos, temas, problemas, argumentos e teorias localizados numa área relativamente recente de estudos, os quais tem sido habitual qualificar como «estudos lógico-filosóficos». De uma forma apropriadamente genérica, e apesar de o território teórico abrangido ser extenso e de contornos por vezes difusos, podemos dizer que na área se investiga um conjunto de questões fundamentais acerca da natureza da linguagem, da mente, da cognição e do raciocínio humanos, bem (...) como questões acerca das conexões destes com a realidade não mental e extralinguística. A razão daquela qualificação é a seguinte: por um lado, a investigação em questão é qualificada como filosófica em virtude do elevado grau de generalidade e abstracção das questões examinadas (entre outras coisas); por outro, a investigação é qualificada como lógica em virtude de ser uma investigação logicamente disciplinada, no sentido de nela se fazer um uso intenso de conceitos, técnicas e métodos provenientes da disciplina de lógica. O agregado de tópicos que constitui a área de estudos lógico-filosóficos é já visível, pelo menos em parte, no Tractatus Logico-Philosophicus de Ludwig Wittgenstein, uma obra publicada em 1921. E uma boa maneira de ter uma ideia sinóptica do território disciplinar abrangido por esta enciclopédia, ou pelo menos de uma porção substancial dele, é extrair do Tractatus uma lista dos tópicos mais salientes aí discutidos; a lista incluirá certamente tópicos do seguinte género, muitos dos quais se podem encontrar ao longo desta enciclopédia: factos e estados de coisas; objectos; representação; crenças e estados mentais; pensamentos; a proposição; nomes próprios; valores de verdade e bivalência; quantificação; funções de verdade; verdade lógica; identidade; tautologia; o raciocínio matemático; a natureza da inferência; o cepticismo e o solipsismo; a indução; as constantes lógicas; a negação; a forma lógica; as leis da ciência; o número. (shrink)

In this note, we review paradoxes like Russell’s, the Liar, and Curry’s in the context of intuitionistic logic. One may observe that one cannot blame the underlying logic for the paradoxes, but has to take into account the particular concept formations. For proof-theoretic semantics, however, this comes with the challenge to block some forms of direct axiomatizations of the Liar. A proper answer to this challenge might be given by Schroeder-Heister’s definitional freedom.

An attractive principle about domains of quantification is the analogue of the Separation Axiom in set theory: restricting a domain by an arbitrary predicate yields a domain. In particular, restricting a domain by a predicate that applies to nothing yields a domain. Thus if there is a nonempty domain, there is an empty domain. But semantics for the empty domain involves some neglected subtleties. Untangling them requires us to revise the usual definition of truth in a model, avoiding the detour (...) through Tarski's notion of satisfaction. (shrink)

Abstract. As a general theory of reasoning—and as a general theory of what holds true under every possible circumstance—logic is supposed to be ontologically neutral. It ought to have nothing to do with questions concerning what there is, or whether there is anything at all. It is for this reason that traditional Aristotelian logic, with its tacit existential presuppositions, was eventually deemed inadequate as a canon of pure logic. And it is for this reason that modern quantification theory, too, with (...) its residue of existentially loaded theorems and patterns of inference, has been claimed to suffer from a defect of logical purity. The law of non-contradiction rules out certain circumstances as impossible—circumstances in which a statement is both true and false, or perhaps circumstances where something both is and is not the case. Is this to be regarded as a further ontological bias? (shrink)

En este artículo delineamos una propuesta para elaborar una lógica de las ficciones desde el enfoque lúdico del pragmatismo dialógico. En efecto, centrados en una de las críticas mayores al enfoque clásico de la lógica: la esquizofrenia estructural de su semántica, recorremos los compromisos ontológicos de las dos tradiciones mayores de la lógica para establecer sus posibilidades y límites en el análisis del discurso ficcional, y la superación desde una perspectiva lúdico pragmática.

In this paper, I will defend a new compositional semantics for single-domain free logic. This semantics makes use of a distinction between the semantic value of a singular term and its semantic referent. The semantic value of a singular term is conceived of as a set that either contains the semantic referent or no element at all. The semantic referent is the object that the term designates. Before I will introduce this new semantics for single-domain predicate and an S5-type modal (...) logic in detail, I will present five related problems of compositionality of the standard semantics for these logical systems. After that I will show in detail how my new proposed alternative semantics can be used to solve nearly all of the outlined five problems. (shrink)

In this paper, I aim to present the main components of my non-standard interpretation of Frege’s views on existence to the English-speaking public. First, I will outline the standard interpretation and show how to a great but not full extent the standard interpretation can be justified on the basis of Frege’s writings. Second, I show that the main error of the standard interpretation consists in the assimilation of the contents of the ordinary language expressions “exist” and “there is” according to (...) Frege. Third, I evaluate possible sources for this unfounded assimilation. After that, I outline my alternative interpretation that distinguishes in opposition to other non-standard interpretations between a substantive and a deflationary part of Frege’s complete conception of existence in analogy to Frege’s analysis of truth and negation. Fifthly, I justify my interpretation by the reconstruction of a so far overlooked master argument of Frege against the above-mentioned assimilation. In the last section, I introduce and discuss five objections against my interpretation that came to my attention. (shrink)

In view of the limitations of classical, free, and modal logics to deal with fictional names, we develop in this paper a four-valued logical framework that we see as a promising strategy for modeling contexts of reasoning in which those names occur. Specifically, we propose to evaluate statements in terms of factual and fictional truth values in such a way that, say, declaring ‘Socrates is a man’ to be true does not come down to the same thing as declaring ‘Sherlock (...) Holmes is a man’ to be so. As a result, our framework is capable of representing reasoning involving fictional characters that avoids evaluating statements according to the same semantic standards. The framework encompasses two logics that differ according to alternative ways one may interpret the relationships among the factual and fictional truth values. (shrink)

Neo-Fregeans such as Bob Hale and Crispin Wright seek a foundation of mathematics based on abstraction principles. These are sentences involving a relation called the abstraction relation. It is usually assumed that abstraction relations must be equivalence relations, so reflexive, symmetric and transitive. In this article I argue that abstraction relations need not be reflexive. I furthermore give an application of non-reflexive abstraction relations to restricted abstraction principles.

Free logics is a family of first-order logics which came about as a result of examining the existence assumptions of classical logic. What those assumptions are varies, but the central ones are that the domain of interpretation is not empty, every name denotes exactly one object in the domain and the quantifiers have existential import. Free logics usually reject the claim that names need to denote in, and of the systems considered in this paper, the positive free logic concedes that (...) some atomic formulas containing non-denoting names are true, while negative free logic rejects even the latter claim. Inclusive logics, which reject, are likewise considered. These logics have complex and varied axiomatizations and semantics, and the goal of this paper is to present an orderly examination of the various systems and their mutual relations. This is done by first offering a formalization, using sequent calculi which possess all the desired structural properties of a good proof system, including admissibility of contraction and cut, while streamlining free logics in a way no other approach has. We then present a simple and unified system of abstract semantics, which allows for a straightforward demonstration of the meta-theoretical properties, and offers insights into the relationship between different logics. The final part of this paper is dedicated to extending the system with modalities by using a labeled sequent calculus, and here we are again able to map out the different approaches and their mutual relations using the same framework. (shrink)

The partial structures approach has two major components: a broad notion of structure (partial structure) and a weak notion of truth (quasi-truth). In this paper, we discuss the relationship between this approach and free logic. We also compare the model-theoretic analysis supplied by partial structures with the method of supervaluations, which was initially introduced as a technique to provide a semantic analysis of free logic. We then combine the three formal frameworks (partial structures, free logic and supervaluations), and apply the (...) resulting approach to accommodate semantic paradoxes. (shrink)

The essays collected in this volume are all concerned with the connection between fiction and truth. This question is of utmost importance to metaphysics, philosophy of language, philosophical logic and epistemology, raising in each of these areas and at their intersections a large number of issues related to creation, existence, reference, identity, modality, belief, assertion, imagination, pretense, etc. All these topics and many more are addressed in this collection, which brings together original essays written from various points of view by (...) philosophers of diverse trends. These essays constitute major contributions to the current debates that the connection between truth and fiction continually enlivens, and give a sense of the directions in which research on this question is heading. Contributors: Fred Adams, Frederick Kroon, Robert Howell, Brendan Murday, Terence Parsons, Graham Priest, Erich Rast, Manuel Rebuschi, Marion Renauld, R.M. Sainsbury, Grant Tavinor, Alberto Voltolini. (shrink)

This paper presents rules in sequent calculus for a binary quantifier I to formalise definite descriptions: Ix[F, G] means ‘The F is G’. The rules are suitable to be added to a system of positive free logic. The paper extends the proof of a cut elimination theorem for this system by Indrzejczak by proving the cases for the rules of I. There are also brief comparisons of the present approach to the more common one that formalises definite descriptions with a (...) term forming operator. In the final section rules for I for negative free and classical logic are also mentioned. (shrink)

This paper presents rules of inference for a binary quantifier I for the formalisation of sentences containing definite descriptions within intuitionist positive free logic. I binds one variable and forms a formula from two formulas. Ix[F, G] means ‘The F is G’. The system is shown to have desirable proof-theoretic properties: it is proved that deductions in it can be brought into normal form. The discussion is rounded up by comparisons between the approach to the formalisation of definite descriptions recommended (...) here and the more usual approach that uses a term-forming operator ι, where ιxF means ‘the F’. (shrink)

We provide an application of a sequent calculus framework to the formalization of definite descriptions. It is a continuation of research undertaken in [20, 22]. In the present paper a so-called free description theory is examined in the context of different kinds of free logic, including systems applied in computer science and constructive mathematics for dealing with partial functions. It is shown that the same theory in different logics may be formalised by means of different rules and gives results of (...) varying strength. For all presented calculi a constructive cut elimination is provided. (shrink)

The paper presents a uniform proof-theoretic treatment of several kinds of free logic, including the logics of existence and definedness applied in constructive mathematics and computer science, and called here quasi-free logics. All free and quasi-free logics considered are formalised in the framework of sequent calculus, the latter for the first time. It is shown that in all cases remarkable simplifications of the starting systems are possible due to the special rule dealing with identity and existence predicate. Cut elimination is (...) proved in a constructive way for sequent calculi adequate for all logics under consideration. (shrink)

The rule of universal instantiation appears to be subject to counterexamples, although the rule of existential generalization is not subject to the same doubts. This paper is a survey of ways of responding to this problem, both conservative and revisionist. The conclusion drawn is that logical validity should be defined in terms of assertibility in a context rather than in terms of truth on an interpretation. Contexts are here defined, not in terms of the attitudes of the interlocutors, but in (...) terms of the goals of conversation, and assertibility is explained in terms of cooperation. (shrink)

In her book Fiction and Metaphysics (1999) Amie Thomasson, influenced by the work of Roman Ingarden, develops a phenomenological approach to fictional entities in order to explain how non-fictional entities can be referred to intrafictionally and transfictionally, for example in the context of literary interpretation. As our starting point we take Thomasson’s realist theory of literary fictional objects, according to which such objects actually exist, albeit as abstract and artifactual entities. Thomasson’s approach relies heavily on the notion of ontological dependence, (...) but its precise semantics has not yet been developed. Moreover, the modal approach to the notion of ontological dependence underlying the Artifactual Theory has recently been contested by several scholars. The main aims of this paper are (i) to develop a semantic approach to the notion of ontological dependence in the context of the Artifactual Theory of fiction, and in so doing bridge a number of philosophical and logical gaps; (ii) to generalize Thomasson’s categorial theory of ontological dependence by reconstructing ontological categories of entities purely in terms of different structures of ontological dependence, rather than in terms of the basic kinds of entities the categorical entities depend on. (shrink)

La réflexion philosophique sur la non-existence est une thématique qui a été abordée au commencement même de la philosophie et qui suscite, depuis la publication en 1905 de « On Denoting » par Russell, les plus vifs débats en philosophie analytique. Cependant, le débat féroce sur la sémantique des noms propres et des descriptions définies qui surgirent suite à la publication du « On Referring » par Strawson en 1950 n’engagea pas d’étude systématique de la sémantique des fictions. En fait, (...) le développement systématique d’un lien qui articule approches logiques, philosophiques et littéraires de la fiction devait attendre les travaux de John Woods publiés en 1974 dans son livre The Logic of Fiction : A Philosophical Sounding of Deviant Logic. Un des enjeux les plus excitants du livre de Woods se situe au niveau de l’interaction entre les points de vue internalistes ou interne-à-l’histoire (principalement pragmatiques) et les points de vue externalistes ou externe-à-la-fiction (principalement sémantiques). Sur ce point, Woods fut le premier à formuler une sémantique pour l’opérateur de fiction à lire comme « selon l’histoire… » en relation à la notion logique de portée, ce qui permettait l’étude de l’internalisme et de l’externalisme. Suite au livre de Woods, loin de s’essouffler, les débats trouvaient une nouvelle impulsion. Le fait pertinent pour notre article est que la tradition phénoménologique également, l’étude de la fiction a joué un rôle central. En effet, l’une des problématiques les plus sujettes à controverses dans l’intentionnalité est celle de l’indépendance à l’existence, c’est-à-dire le fait que les actes intentionnels n’ont pas besoin d’être forcément dirigés vers un objet existant. Influencée par les travaux de Roman Ingarden (1893-1970), l’un des plus importants disciples de Husserl, Amie L. Thomasson développe le concept phénoménologique de dépendance ontologique en vue d’expliquer les processus de références inter- et transfictionnels – dans le contexte de l’interprétation littéraire par exemple. L’enjeu essentiel de cet article est de proposer une reconstruction multimodale bi-dimensionnelle de la théorie des personnages fictionnels de Ingarden-Thomasson. Cette théorie qui entend prendre au sérieux le fait que les fictions sont des créations montre la voie pour une articulation entre les approches internalistes et externalistes. Nous motivons certains changements quant à l’approche artéfactuelle - incluant une sémantique appropriée pour l’opérateur de fictionalité qui, nous l’espérons, éveillera l’intérêt des théoriciens de la littérature. L’article est à d’autres égards un panorama de la façon dont différents concepts d’intentionnalité pourraient fonder différentes sémantiques formelles pour la fictionalité. Nous proposerons enfin un cadre dialogique qui est une extension modale d’un certain système de preuve développé par Matthieu Fontaine et Juan Redmond. Le cadre dialogique développe la contrepartie inférentielle de la sémantique bi-dimensionnelle introduite par Shahid Rahman et Tero Tulenheimo dans un article récent. (shrink)

The major argument against Ramsey-style epistemic structural realism is the model-theoretic refinement of Newman’s objection against Russell, presented in Ketland : 409–424, 2004), where a technical result is interpreted as showing that the Ramsey-sentence approach collapses into instrumentalism. This paper addresses some questions raised by the application of model theory to the scientific realism debate. Firstly, I will suggest three different formal semantics for the positions in the debate. Then, some technicalities of Ketland’s result will be scrutinized in light of (...) comments by Zahar and Demopoulos. Finally, I will formalize Ketland’s argument by means of an intensional operator and focus on one problematic premise. The conclusion is that, with some adjustments, the Ramsey-sentence approach can represent an intermediate position between realism and instrumentalism, but the term “structuralism” does not suit it well. (shrink)

This is a companion paper to Braüner where a natural deduction system for propositional hybrid logic is given. In the present paper we generalize the system to the first-order case. Our natural deduction system for first-order hybrid logic can be extended with additional inference rules corresponding to conditions on the accessibility relations and the quantifier domains expressed by so-called geometric theories. We prove soundness and completeness and we prove a normalisation theorem. Moreover, we give an axiom system first-order hybrid logic.

In this paper we give axiom systems for classical and intuitionistic hybrid logic. Our axiom systems can be extended with additional rules corresponding to conditions on the accessibility relation expressed by so-called geometric theories. In the classical case other axiomatisations than ours can be found in the literature but in the intuitionistic case no axiomatisations have been published. We consider plain intuitionistic hybrid logic as well as a hybridized version of the constructive and paraconsistent logic N4.

The standard relation of logical consequence allows for non-standard interpretations of logical constants, as was shown early on by Carnap. But then how can we learn the interpretations of logical constants, if not from the rules which govern their use? Answers in the literature have mostly consisted in devising clever rule formats going beyond the familiar what follows from what. A more conservative answer is possible. We may be able to learn the correct interpretations from the standard rules, because the (...) space of possible interpretations is a priori restricted by universal semantic principles. We show that this is indeed the case. The principles are familiar from modern formal semantics: compositionality, supplemented, for quantifiers, with topic-neutrality. (shrink)

I would like to attack a certain view: The view that the concept of identity can fail to apply to some things although, for some positive integer n, we have n of them. The idea of entities without self-identity is seriously entertained in the philosophy of quantum mechanics. It is so pervasive that it has been labelled the Received View. I introduce the Received View in Section 1. In Section 2 I explain what I mean by entity, and I argue (...) that supporters of the Received View should agree with my characterization of the corresponding notion of entity. I also explain what I mean by identity, and I show that supporters of the Received View agree with my characterization of that notion. In Section 3 I argue that the concept of identity, so characterized, is one with the concept of oneness. Thus, it cannot but apply to what belongs to a collection with n elements, n being a positive integer. In Section 4 I add some considerations on the primitiveness of identity or unity and the status of the Identity of Indiscernibles. In Section 5 I address the problem of how reference to indiscernible objects with identity can be achieved. (shrink)

In previous work we gave an approach, based on labelled natural deduction, for formalizing proof systems for a large class of propositional modal logics that includes K, D, T, B, S4, S4.2, KD45, and S5. Here we extend this approach to quantified modal logics, providing formalizations for logics with varying, increasing, decreasing, or constant domains. The result is modular with respect to both properties of the accessibility relation in the Kripke frame and the way domains of individuals change between worlds. (...) Our approach has a modular metatheory too; soundness, completeness and normalization are proved uniformly for every logic in our class. Finally, our work leads to a simple implementation of a modal logic theorem prover in a standard logical framework. (shrink)

Classical logic counts sentences such as ‘Alice is identical with Alice’ as logically true. A standard objection to classical logic is that Alice’s self-identity, for instance, is not a matter of logic because the identity of particular objects is not a matter of logic. For this reason, many philosophers argue that classical logic is not the right logic, and that it should be abandoned in favour of free logic — logic free of existential commitments with respect to singular terms. In (...) most standard free logics, sentences such as ‘Alice is identical with Alice’ are not logically true. This paper argues that this objection from existential commitments is some- what superficial and that there is a deeper reason why ‘Alice is identical with Alice’ should not be considered a logical truth. Indeed, a key fundamental thought about the nature of logic is that a logical truth is true in virtue of its logical form. The fundamental problem I raise is that a sentence such as ‘Alice is identical with Alice’ appears to not even be true in virtue of its logical form. Thus this paper argues that given that such a sentence is not true in virtue of its logical form, it should not be counted as logically true. It moreover argues, on the same grounds, that even the sentences which free logicians regard as logically true shouldn’t be regarded as logically true. So in this sense free logic is no repair to classical logic. (shrink)

The practice of thought experimentation plays a central role in contemporary philosophical methodology. Many philosophers rely on thought experimentation as their primary and even sole procedure for testing theories about the natures of properties and relations. This test procedure involves entertaining hypothetical cases in imaginative thought and then undergoing intuitions about the distribution of properties and relations in them. A theory’s comporting with an intuition is treated as evidence in favour of it; but a clash is treated as evidence against (...) the theory and may even be regarded as falsifying it. -/- The epistemic power of thought experimentation is mysterious. How can experiments carried out within the mind enable us to discover truths about the natures of properties and relations like knowledge, causation, personal identity, reference, meaning, consciousness, beauty, justice, morality, and free will? This epistemological challenge is urgent, but a model of philosophical thought experimentation would seem to be a necessary propaedeutic to any serious discussion of it. An adequate model would make the relevant test procedure explicit, thereby assisting in the identification of points of potential epistemic vulnerability. -/- In this monograph I advance the propaedeutical model-building work already done by Timothy Williamson, Anna-Sara Malmgren, and Jonathan Ichikawa and Benjamin Jarvis. Following the lead of these philosophers, I focus on a single Gettier-style thought experiment and the problem of identifying the real content of the Gettier intuition. My first contribution is to establish the inadequacy of all of the existing models. Each of them, I argue, fails to solve the content problem. It emerges from my discussion, however, that Ichikawa and Jarvis’s truth in fiction approach holds out the prospect of a solution. -/- My second contribution is to develop and defend a new way of implementing the general idea behind the truth in fiction approach. The model I put forward does a better overall job of modelling Gettier-style thought experiments than any of the existing models. It has none of the defects which render those models inadequate and Iam unable to find any major defects peculiar to it. This should make us feel confident that my model is adequate. Moreover, since the Gettier-style thought experiment I focus on is paradigmatic, we should also feel confident that my model will generalise naturally to other philosophical thought experiments. (shrink)

Table of Formal and Descriptivists Ontologists (PDF - from Bernard Bolzano to present time) Ontologists of the 19th and 20th Centuries (a selection of critical judgments about some of the greatest philosophers of the recent past) Living Ontologists (a list of authors with an interest in ontology, with synthetic bibliographies).

Husserlian Essentialism is the view, maintained byEdmundHusserl throughout his career, that necessary truths obtain because essentialist truths obtain. In this thesis I have two goals. First, to reconstruct and flesh out Husserlian Essentialism and its connections with surrounding areas of Husserl's philosophy in full detail – something which has not been done yet. Second, to assess the theoretical solidity of the view. As regards the second point, after having presented Husserlian Essentialism in the first two chapters, I raise a serious (...) problem for it in Chapter 3. In the remainder of the thesis I endeavour to solve the problem. In order to do so, I propose to amend both Husserl's theory of essence and his theory of predication. The bulk of the emendation consists in working out an account of essence and an account of predication that do not presuppose, or in any way imply, the claims that: 1) for a universal to be in the essence of an object, either the object or one of its parts must instantiate the universal; 2) for a universal to be truly predicated of an object, either the object or one of its parts must instantiate the universal. These claims, notice, apart from being what gets Husserl in trouble, are well entrenched not only in Husserl's, but in most theories of essence and predication. It is thus interesting to see what an alternative option may be – even regardless of the Husserlian setting in which I work it out. (shrink)

Dialogical logic is a game-theoretical approach to logic. Logic is studied with the help of certain games, which can be thought of as idealized argumentations. Two players, the Proponent, who puts forward the initial thesis and tries to defend it, and the Opponent, who tries to attack the Proponent’s thesis, alternately utter argumentative moves according to certain rules. For a long time the dialogical approach had been worked out only for classical and intuitionistic logic. The seven papers of this dissertation (...) show that this narrowness was uncalled for. The initial paper presents an overview and serves as an introduction to the other papers. Those papers are related by one central theme. As each of them presents dialogical formulations of a different non-classical logic, they show that dialogical logic constitutes a powerful and flexible general framework for the development and study of various logical formalisms and combinations thereof. As such it is especially attractive to logical pluralists that reject the idea of “the single correct logic”. The collection contains treatments of free logic, modal logic, relevance logic, connexive logic, linear logic, and multi-valued logic. (shrink)

On the one hand, logic has (or ought to have) nothing to do with metaphysics; it ought to have nothing to do with questions concerning what there is, or whether there is anything at all. On the other hand, metaphysics can hardly get off the ground without the help of logical analysis; to be is to be a truth-maker, and the search for truth-makers requires that we lay open the logical structure of our language. So something’s gotta give: either logical (...) analysis is metaphysically biased, or metaphysicians must make up their mind before resorting to logical analysis. Or both. (shrink)

In section III of Pryor 2006a, I argued against the view that the mere fact that a thought- type is hyper-reliable directly gives one justification to believe a thought of that type. A close alternative says that our merely appreciating that the thought-type is hyper-reliable directly gives us that justification.