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In her book Deviant Logic (1974), Susan Haack argued for a “pragmatist” conception of logic. This conception holds that, (i) logic is a theory on a par with other scientific theories, differing only from such theories by its degree of generality and (ii) the choice of a particular logic is to be made based on pragmatist principles, namely, economy, coherence, and simplicity. This view was contrasted, in this book, with an “absolutist” view of logic, according to which logical laws are necessary and immune to revision. Two decades later, however, Haack acknowledged, in the Introduction to an enlarged version of the same book, that she would not approach the question of the revisability of logic in the same way she did earlier. What was missing in her first book was a distinction between the question of the necessity of the laws of logic and the question of our fallibility in recognizing which are the true laws of logic and what structures are essential to representation. She also acknowledged that this change was mainly influenced by Peirce, with whose work she had “only the most superficial acquaintance twenty years ago”. In this context, this paper has two aims: (1) to show that, in Philosophy of Logics, we can find elements that reveal a tension between her early “pragmatic” views and her changing views on the nature of logic; (2) to present some hypotheses about the role Peirce may have had in this change.

It is widely recognized the importance of the “color-exclusion problem” for the changes that occurred in Wittgenstein’s thought in 1929. Little is known, however, about the relation between the logical analysis of colour statements (task undertaken by Wittgenstein as soon as he start to work in 1929) and the changes that occur in the notion of “generality” in contrast to the Tractarian approach. This paper aims at arguing that there is a close relation between the analysis of statements about chromatic patches in visual space and the abandonment of one of the main characteristic features of Tractarian elementary propositions , namely the fact that they do not leave “room for maneuver” to the world. Indeed, the introduction of “incomplete elementary propositions ”, in chapter IX of Philosophical Remarks, argues for the need to introduce propositions which, though elementary, would yet contain, in their senses, a vagueness or indeterminacy. At the time of the Tractatus, this vagueness was symbolized by a general, non-elementary proposition (the scope of this generality was highlighted by a logical prototype). Now, in Philosophical Remarks, the notions of “elementary” and “general” propositions can no longer be opposed, which necessarily leads to a new conception of generality. We will try to show the way that leads to this new theory of generality. Moreover, we hope our analysis can throw some light on the notion of “complete analysis”, notion which will undergo substantial changes from the Tractatus to the Philosophical Remarks.

O estudo do comportamento de fluidos é um antigo domínio das ciências da natureza. Ultimamente, fenômenos de engenharia que eram estudados empiricamente passaram a ser estudados com auxílio computacional. A Dinâmica de Fluidos Computacional (DFC) é a área da ciência da computação que estuda métodos computacionais para simulação de escoamento de fluidos, e muitas vezes é a forma mais prática, ou a única, de se observar fenômenos de interesse no escoamento. Este projeto de Mestrado procurou investigar, no âmbito da simulação de um escoamento bifásico, métodos computacionais para representar a interface entre dois fluidos imiscíveis. A separação dos fluidos por meio de uma interface é necessária para assegurar que, propriedades como viscosidade e densidade, específicas de cada fluido, sejam utilizadas corretamente para o cálculo do movimento de seus respectivos fluidos. Desenvolvemos um método lagrangeano sem a utilização de malhas com o objetivo de suprir algumas restrições de trabalhos prévios. Para representar a interface entre os dois fluidos, este método utiliza uma técnica de reconstrução de superfícies baseada em aproximações de superfícies algébricas de alta ordem. Os resultados numéricos reportados neste documento evidenciam o potencial da nossa abordagem The study of the behaviour of fluids is an ancient field in natural sciences. Recently, engineering phenomena that were empirically studied started to be done with computacional aid. The Computational Fluid Dynamics (CFD) is the area of science that studies computational methods for computer simulation of fluid flow, and often is the most practical way, or the only, to observe phenomena of interest in flow. This Masters degree project sought to investigate, in the context of the simulation of biphasic flows, computational methods to represent the interface between two immiscible fluids. The separation of fluids by the means of an interface is required to ensure that, during the simulation, the physical properties of a fluid, like density and viscosity (specific of each fluid) are properly used in the calculus of the respective fluid motion. We developed a lagrangean method without the use of mesh with the goal of alleviating some of the previous works restrictions. To represent the interface between the two fluids, this method uses a surface reconstruction technique based on approximations of high order algebraic surfaces. The numerical results reported herein show the potential of our approach

Este trabalho examina duas analogias frequentemente empregadas por Ludwig Wittgenstein para a descrição da linguagem ao longo de sua obra. São elas: a concepção da linguagem como um cálculo autônomo dotado de regras fixas e determinadas, sustentada pelo filósofo no período intermediário de seu desenvolvimento filosófico, e a noção de jogos de linguagem, extensivamente mobilizada nas Investigações Filosóficas. Além disso, busca-se mostrar quais são os motivos que levaram o autor a caracterizar, retrospectivamente, também sua abordagem lógico-sintática no Tractatus Logico-Philosophicus como parte de uma concepção da linguagem como cálculo. Por fim, mostra-se como a elucidação do que está por trás de cada um desses dois modelos pode auxiliar na compreensão das transformações ocorridas ao longo do chamado período intermediário. This study examines two analogies that are frequently employed by Ludwig Wittgenstein in order to describe language throughout his work. Namely: the conception of language as an autonomous calculus with fixed and determinate rules, held by the philosopher during the intermediate period of his philosophical development, and the notion of language games, extensively used in the Philosophical Investigations. Furthermore, I try to show what were the reasons that made the author characterize, retrospectively, also his logico-syntactical account in the Tractatus Logico-Philosophicus as part of the conception of language as a calculus. Finally, I show how the elucidation of what lies behind each one of these two models may help in understanding the transformations that took place throughout the intermediate period.