In this paper, we provide a new formulation of a coherence theory of truth using the resources of the partial structures approach − in particular the notions of partial structure and quasi-truth. After developing this new formulation, we apply the resulting theory to the philosophy of mathematics, and argue that it can be used to develop a new account of nominalism in mathematics. This application illustrates the strength and usefulness of the proposed formulation of a coherence theory of truth.Neste artigo, (...) propomos uma nova formulação de uma teoria coerentista da verdade utilizando os recursos da abordagem de estruturas parciais - em particular as noções de estrutura parcial e quase-verdade. Após desenvolver esta formulação, aplicamos a teoria resultante à filosofia da matemática, e argumentamos que aquela pode ser usada para desenvolver um novo tratamento do nominalismo na matemática. Esta aplicação ilustra a força e utilidade da formulação proposta de uma teoria coerentista da verdade. (shrink)

This paper is a historical companion to a previous one, in which it was studied the so-called abstract Galois theory as formulated by the Portuguese mathematician José Sebastião e Silva ). Our purpose is to present some applications of abstract Galois theory to higher-order model theory, to discuss Silva's notion of expressibility and to outline a classical Galois theory that can be obtained inside the two versions of the abstract theory, those of Mark Krasner and of Silva. Some comments are (...) made on the universal theory of structures. (shrink)

In order to develop an account of scientific rationality, two problems need to be addressed: (i) how to make sense of episodes of theory change in science where the lack of a cumulative development is found, and (ii) how to accommodate cases of scientific change where lack of consistency is involved. In this paper, we sketch a model of scientific rationality that accommodates both problems. We first provide a framework within which it is possible to make sense of scientific revolutions, (...) but which still preserves some (partial) relations between old and new theories. The existence of these relations help to explain why the break between different theories is never too radical as to make it impossible for one to interpret the process in perfectly rational terms. We then defend the view that if scientific theories are taken to be quasi-true, and if the underlying logic is paraconsistent, it's perfectly rational for scientists and mathematicians to entertain inconsistent theories without triviality. As a result, as opposed to what is demanded by traditional approaches to rationality, it's not irrational to entertain inconsistent theories. Finally, we conclude the paper by arguing that the view advanced here provides a new way of thinking about the foundations of science. In particular, it extends in important respects both coherentist and foundationalist approaches to knowledge, without the troubles that plague traditional views of scientific rationality. (shrink)

The structure of natural languages is usually studied from three major different but interconnected points of view: syntax, semantics, and pragmatics. If we consider that the main purpose of natural languages is communication, we should consider another dimension for languages, which deals with the influence of internal states of communicating individuals on meanings. Such a dimension we refer to as internalism. Within this context, internalism cannot be confused with psycholinguistics, in the same way pragmatics cannot be confused with sociolinguistics. In (...) particular, we argue, language is tied to its systematic use. This view leads us to a non-realist perspective on linguistics. We analyze the role of natural languages into dialogues, by comparing our proposal to the dialogical approach to logic, which considers a dialogue as a game. Within our approach, there is no way to guarantee that two parties involved in a dialogue are playing the same game, due to unavoidable differences in their respective internal states. Another contribution of this paper is to argue that semantics plays a more fundamental role than syntax in the cognitive acquisition of languages. (shrink)

We present an axiomatic framework for semantics that can be applied to natural and formal languages. Our main goal is to suggest a very simple mathematical model that describes fundamental cognitive aspects of the human brain and that can still be applied to artificial intelligence. One of our main results is a theorem that allows us to infer syntactical properties of a language out of its corresponding semantics. The role of pragmatics in semantics in our mathematical framework is also discussed.

The mathematical concept of pragmatic truth, first introduced in Mikenberg, da Costa and Chuaqui (1986), has received in the last few years several applications in logic and the philosophy of science. In this paper, we study the logic of pragmatic truth, and show that there are important connections between this logic, modal logic and, in particular, Jaskowski's discussive logic. In order to do so, two systems are put forward so that the notions of pragmatic validity and pragmatic truth can (...) be accommodated. One of the main results of this paper is that the logic of pragmatic truth is paraconsistent. The philosophical import of this result, which justifies the application of pragmatic truth to inconsistent settings, is also discussed. (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 issue of what consequences to draw from the existence of non-classical logical systems has been the subject of an interesting debate across a diversity of fields. In this paper the matter of alternative logics is considered with reference to a specific belief system and its propositions :the Azande are said to maintain beliefs about witchcraft which, when expressed propositionally, appear to be inconsistent. When the Azande have been presented with such inconsistencies, they either fail to see them as such (...) or else accept them as non-problematical. Is our knowledge of logical truths a relative and culturally determined phenomenon, or is there some (transcendent) criterion that allows us to adjudicate between alternative logical systems? The authors propose an approach for resolving disputes about the status of Azande reasoning which assumes a paraconsistent framework, thus providing a new perspective on this debate. (shrink)

After mentioning the cogent connection between pure semantics and the particular set theoretical framework in which it is formulated, some issues regarding the conceptual status of semantics itself, as well as its relationship to logic, are concisely raised.

We formulate Suppes predicates for various kinds of space-time: classical Euclidean, Minkowski's, and that of General Relativity. Starting with topological properties, these continua are mathematically constructed with the help of a basic algebra of events; this algebra constitutes a kind of mereology, in the sense of Lesniewski. There are several alternative, possible constructions, depending, for instance, on the use of the common field of reals or of a non-Archimedian field (with infinitesimals). Our approach was inspired by the work of Whitehead (...) (1919), though our philosophical stance is completely different from his. The structures obtained are idealized constructs underlying extant, physical space-time. (shrink)

In this paper, we provide a new formulation of a coherence theory of truth using the resources of the partial structures approach − in particular the notions of partial structure and quasi-truth. After developing this new formulation, we apply the resulting theory to the philosophy of mathematics, and argue that it can be used to develop a new account of nominalism in mathematics. This application illustrates the strength and usefulness of the proposed formulation of a coherence theory of truth.

In this first paper of a series of works on the foundations of science, we examine the significance of logical and mathematical frameworks used in foundational studies. In particular, we emphasize the distinction between the order of a language and the order of a structure to prevent confusing models of scientific theories with first-order structures, and which are studied in standard model theory. All of us are, of course, bound to make abuses of language even in putatively precise contexts. This (...) is not a problem—in fact, it is part of scientific and philosophical practice. But it is important to be sensitive to the dierent uses that structure, model, and language have. In this paper, we examine these topics in the context of classical logic; only in the last section we touch upon briefly on non-classical ones. (shrink)

Reviewed Works:Chris Mortensen, Inconsistent Mathematics.Chris Mortensen, Peter Lavers, Category Theory.William James, Closed Set Sheaves and Their Categories.Chris Mortensen, Joshua Cole, Foundations: Provability, Truth and Sets.

This chapter contains sections titled: Introduction Paraconsistent Logic and Latin America Thinking about Logic The Nature of Paraconsistent Logic A History of Paraconsistent Logic Philosophical Aspects of Paraconsistent Logic References Further Reading.

Neste ensaio, refletimos sobre a unidade e a universalidade da lógica, por meio de duas questões fundamentais. Em primeiro lugar, discutimos se, dentre as várias lógicas existentes atualmente, haveria alguma melhor do que as outras. Em segundo, debruçamo-nos sobre o problema de saber se o mundo real é governado por uma determinada lógica. Remetendo as questões aos seus fundamentos, defendemos o pluralismo e mostramos que a avaliação das lógicas não se dá por questões de índole meramente formal, envolvendo princípios históricos, (...) pragmáticos e dialéticos ligados aos diversos contextos racionais aos quais elas são aplicadas. Mostramos ainda que o mundo real não é governado por nenhuma lógica específica, mas por variadas lógicas, e que há sempre uma espécie de ambiguidade e um jogo adaptativo entre os aspectos reais do mundo e os formais da lógica. (shrink)

We formulate Suppes predicates for various kinds of space-time: classical Euclidean, Minkowski's, and that of General Relativity. Starting with topological properties, these continua are mathematically constructed with the help of a basic algebra of events; this algebra constitutes a kind of mereology, in the sense of Lesniewski. There are several alternative, possible constructions, depending, for instance, on the use of the common field of reals or of a non-Archimedian field. Our approach was inspired by the work of Whitehead, though our (...) philosophical stance is completely different from his. The structures obtained are idealized constructs underlying extant, physical space-time. (shrink)

It is usually stated that quantum mechanics presents problems with the identity of particles, the most radical position—supported by E. Schrödinger—asserting that elementary particles are not individuals. But the subject goes deeper, and it is even possible to obtain states with an undefined particle number. In this work we present a set theoretical framework for the description of undefined particle number states in quantum mechanics which provides a precise logical meaning for this notion. This construction goes in the line of (...) solving a problem posed by Y. Manin, namely, to incorporate quantum mechanical notions at the foundations of mathematics. We also show that our system is capable of representing quantum superpositions. (shrink)

This paper is a summary of a lecture in which I presented some remarks on Gödel’s incompleteness theorems and their meaning for the foundations of physics. The entire lecture will appear elsewhere.

In order to develop an account of scientific rationality, two problems need to be addressed: (i) how to make sense of episodes of theory change in science where the lack of a cumulative development is found, and (ii) how to accommodate cases of scientific change where lack of consistency is involved. In this paper, we sketch a model of scientific rationality that accommodates both problems. We first provide a framework within which it is possible to make sense of scientific revolutions, (...) but which still preserves some (partial) relations between old and new theories. The existence of these relations help to explain why the break between different theories is never too radical as to make it impossible for one to interpret the process in perfectly rational terms. We then defend the view that if scientific theories are taken to be quasi-true, and if the underlying logic is paraconsistent, it’s perfectly rational for scientists and mathematicians to entertain inconsistent theories without triviality. As a result, as opposed to what is demanded by traditional approaches to rationality, it’s not irrational to entertain inconsistent theories. Finally, we conclude the paper by arguing that the view advanced here provides a new way of thinking about the foundations of science. In particular, it extends in important respects both coherentist and foundationalist approaches to knowledge, without the troubles that plague traditional views of scientific rationality. (shrink)

Throughout the last two decades, Newton da Costa and his collaborators have developed some frameworks to help the interpretation of science. Two of them are particularly noteworthy: partial structures and quasi-truth (that provide a way of accommodating the openness and partiality of scientific activity), and quasi-set theory (that allows one to take seriously the idea, put forward by several physicists, that we can't meaningfully apply the notion of identity to quantum particles). In this paper I explore the interconnection (...) between these two frameworks. After reviewing the extant formulations of quasi-truth and quasi-set theory, I suggest a way of combining them, advancing a formulation of quasi-truth in quasi-set theory. In this way, a good sense can be made of the idea that quantum mechanics, if not true, is at least quasi-true. I then explore an application of this combined framework, arguing that it provides a conceptual setting appropriate to overcome two (philosophical) difficulties in van Fraassen's modal interpretation of quantum mechanics. (shrink)

Newton da Costa and Steven French have argued that the concept of partial truth plays an important role in our understanding of significant aspects of scientific practice: from the status of scientific theories through the understanding of inconsistency in science to the nature of induction. In this paper, I use the concept of partial truth and the associated framework of partial structures to offer a formulation of the concept of visual evidence, and I examine some of the roles (...) that this notion plays in scientific activity. (shrink)

. In this paper, I examine three models of reduction. The first, and the most restrictive, is the model developed by Ernest Nagel as part of the logical empiricist program. The second, articulated by Jerry Fodor, is significantly broader, but it seems unable to make sense of a salient feature of scientific practice. The third, and the most lenient, model is developed within Newton da Costa and Steven French’s partial structures approach. I argue that the third model preserves (...) the benefits of Fodor’s proposal, and it is still able to accommodate relevant aspects of scientific practice. In particular, it offers a conception of reduction without reductionism, and an account of the relation between reduced and reducing theories via unsharp mappings and partial structures—even in the presence of incomplete information. (shrink)

Este artigo busca refletir sobre condições iniciais da sociedade pré- humana explicando como dois fenômenos biológicos – adaptativos, a bipedalização e neotenia, ajudaram a emergir no homem características próprias humanas tais como a solidariedade. Procura também lançar critica se a Teoria da Evolução pode ou não explicar comportamentos humanos complexos.

O marketing esportivo, que movimenta bilhões de dólares em todo o mundo, assumiu um novo perfil com a entrada em campo das mídias sociais. A gestão das marcas nestes espaços virtuais exige agilidade, pró-atividade e sobretudo disposição para interagir com os consumidores. Este estudo analisa as estratégias da Nike e da Adidas no Facebook e no Twitter durante a realização da Copa do Mundo de 2014 no Brasil e conclui que, apesar da tradicional agressividade das marcas no mercado, a apropriação (...) deste espaço ainda se faz de modo tímido e nem sempre adequado pela ausência de uma cultura digital de comunicação. (shrink)

Gennaro Chtjerchia, Dynamics of meaning: anaphora, presupposition, and the the of grammar. Chicago and London: The University of Chicago Press, 1995.xv+ 270 pp, £59.95, £31.95 G. Pr...

Based on da Costa's and French's notions of partial structures and pragmatic truth, this paper examines two possible characterizations of the concept of empirical adequacy, one depending on the notion of partial isomorphism, the other on the hierarchy of partial models of phenomena, and both compatible with an empiricist view. These formulations can then be employed to illuminate certain aspects of scientific practice.An empirical theory must single out a specific part of the world, establish reference to that part, and (...) say—by way of contingent, substantial claim about the world—that its models fit that. Now, how exactly can this be done? Bas C. van Fraassen. (shrink)

Neste texto, exploramos algumas das teses mais importantes desenvolvidas por Newton da Costa, ao longo da sua carreira filosófica. Apresentamos conceitos e ideias de suas obras, que reúnem contribuições no campo da lógica e da filosofia da ciência. A atenção será voltada aos trabalhos Sistemas formais inconsistentes, Ensaios sobre os fundamentos da lógica e O conhecimento científico, dos quais explicitaremos as temáticas e alguns dos conceitos e resultados alcançados pelo filósofo. Objetivamos com essa apresentação ressaltar a originalidade de (...) seu pensamento, isto é, de que modo suas respostas pessoais se dirigem a questões relevantes da história da filosofia, da matemática e da lógica. (shrink)

In this paper a constructive empiricist account of scientific change is put forward. Based on da Costa's and French's partial structures approach, two notions of empirical adequacy are initially advanced (with particular emphasis on the introduction of degrees of empirical adequacy). Using these notions, it is shown how both the informativeness and the empirical adequacy requirements of an empiricist theory of scientific change can then be met. Finally, some philosophical consequences with regard to the role of structures in this (...) context are drawn.Now, we daily see what science is doing for us. This could not be unless it taught us something about reality; the aim of science is not things themselves, as the dogmatists in their simplicity imagine, but the relations between things; outside those relations there is no reality knowable. (shrink)

This paper intends to report on the beginning of the publications of Newton da Costa outside Brazil. Two mathematicians played an important role in this beginning: Marcel Guillaume from the University of Clermont-Ferrand and Paul Dedecker from the Universities of Lille and Liège. At the same time we recall the role played by Newton da Costa and Jayme Machado Cardoso in the development of what we call here the School of Curitiba [Escola de Curitiba]. Paraconsistent logic (...) was initiated in this school under the influence of Newton da Costa. As another contribution of this school we mention the development of the theory of quasigroups; Jayme Machado Cardoso’s name has been given, by Sade, to some particular objects which are now called Cardoso quasigroups. (shrink)

Da Costa and French explore the consequences of adopting a 'pragmatic' notion of truth in the philosophy of science. Their framework sheds new light on issues to do with belief, theory acceptance, and the realism-antirealism debate, as well as the nature of scientific models and their heuristic development.

This paper intends to introduce the three issues of Principia which will appear in a sequel honoring Newton da Costa’s 80th birthday. Instead of presenting the papers one by one, as it is common in presentations such as this one, we have left the papers speak by themselves, and instead we have preferred to present to the Brazilian readers, specialty to our students, some aspects of Newton da Costa’s conception of science and of the scientific activity, (...) grounded on the concept of quasi-truth, which he contributed to develop in a rigorous way. Da Costa is known as one of the founding fathers of paraconsistent logic, but his contributions go also to the foundations of physics, theoretical computation, model theory, algebraic logic, lattice theory, applications of non-classical logics to law and technology, etc. But perhaps his main contribution was to provide a basis for the birth of a school of logic in our country, serving as teacher and inspiring new researchers for generations. It is a pleasure to have had so enthusiastic acceptation from the editors of Principia to organize these volumes. I would like to thank the contributors and the editors of Principia, specially Prof. Cezar Mortari for his help in organizing the issue. (shrink)

A first step is taken towards articulating a constructive empiricist philosophy of mathematics, thus extending van Fraassen's account to this domain. In order to do so, I adapt Field's nominalization program, making it compatible with an empiricist stance. Two changes are introduced: (a) Instead of taking conservativeness as the norm of mathematics, the empiricist countenances the weaker notion of quasi-truth (as formulated by da Costa and French), from which the formal properties of conservativeness are derived; (b) Instead of quantifying (...) over spacetime regions, the empiricist only admits quantification over occupied regions, since this is enough for his or her needs. (shrink)