<p>I present a defense of David Lewis's metaphysical theory of Humean Supervenience. I provide novel motivations for his theory, and look to current physical science research for support of the metaphysical theory. I draw heavily on analogies between Humean Supervenience and classical discussions of the nature of space-time. I also defend Humean Supervenience against four major philosophical objections using considerations from physics and metaphysics.</p> / Dissertation

It is near-consensus among those currently working on the semantics of counterfactuals that the correct treatment of counterfactuals (whatever it is) must invoke causal independence in order to rule a particular set of seemingly true counterfactuals – including a famous one called Morgenbesser's Coin (MC) – true. But if we must analyze counterfactuals in terms of causation, this rules out giving a reductive account of causation in terms of counterfactuals, and is, as such, a serious blow to the Humean hope of reducing causation to counterfactual dependence. This dissertation is composed of three self-standing articles. In the first article I argue that counterfactuals like MC are false contrary to appearances; as is the thesis that the correct semantics of counterfactuals must appeal to causal independence. In the second article I argue that there are important, widely-held assumptions about difference-making and its relationship to causation which are false, and which may underlie some of the remaining, most threatening objections to the counterfactual analysis of causation. In the final article I discuss the puzzle of reverse Sobel sequences – an alleged problem for the classic Lewis-Stalnaker semantics for counterfactuals. I argue that none of the extant approaches to the problem are right, and defend a novel solution to the puzzle. If I am correct, reverse Sobel sequences do not threaten the classic analysis. They do, however, give additional evidence for the thesis, forcefully defended by Alan Hájek, that most non-probabilistic 'would'-counterfactuals are false. This motivates placing a stronger emphasis on trying to understand probabilistic counterfactuals first and foremost.

In his paper, The Paradoxes of Time Travel, David Lewis posits a defense for the possibility of time travel by arguing that the grandfather 'paradox' is not, in fact, paradoxical at all. Two alternative solutions to the grandfather paradox are discussed in this paper. The first is a result of Paul Horwich’s reply to Lewis and aims to pit the Lewisian conception of compatibility against Horwich’s improbability defense. Proposed by Nicholas Smith and C.G. Goddu, this theory explains that any attempt at backward time travel will lead to the creation of long strings of improbable coincidences. An alternative thesis of the multiverse is also discussed, wherein it was proposed that instead of traveling into his past, the time traveler enters an alternate, yet completely identical universe. The multiverse thesis did not stand up to any philosophical critique, and it was posited that the thesis changes the nature of the question entirely. It is evident that Lewis’ discussion of the grandfather paradox raises several fundamentally interesting philosophical questions regarding the logical and causal irregularities of changing the past. This paper aims to adress some of these questions through a metaphysical analysis of Lewis' view, backwards causality, and the nature of time itself.

Made available in DSpace on 2014-07-29T15:06:24Z (GMT). No. of bitstreams: 1 RENATO MENDES ROCHA.pdf: 735741 bytes, checksum: 6559707c78ce13d85086e58b691dd7f3 (MD5) Previous issue date: 2010-08-30 / In this dissertation we will defend Lewis Modal Realism (LMR), i.e., the metaphysical hypothesis about the real existence of a plurality of worlds. We will try to show the pragmatic character of Lewis arguments in support of this metaphysics of possible worlds. In this sense, we approximate Lewis (1986) and Quine (1960) and we aim to show that Lewis uses criteria for taking ontological decisions similar to those defended by Quine. These criteria are: simplicity of formulation, theoretical economy and distrust in purely intuitive criteria as only guide for Philosophy. To accomplish our intention, we divided the text in three chapters. In the first we present the philosophical benefits of LMR that demonstrate the theoretical utility of possible-worlds talk. These benefits are related to important concepts in Philosophy of Language and Epistemology, such as, Modality, Counterfactuals and a uniform treatment to Properties and Propositions. The second chapter is divided into two parts. At first we present the philosophical background we believe is related to Lewis philosophy. A neo-humean scenario and the resumption of metaphysics discussion in contemporary analytic philosophy compose this background. In the second part we present three fundamental thesis formulate by Lewis the consistence of his Modal Realism: concreteness, isolation and plenitude. In the third and latter chapter we discuss two criticism of LMR: (a) David Armstrong & Peter Forrest (1984) and (b) Susan Haack (1977). Each of these papers present criticism from distinct points of view. The first aims to identify a paradox in the metaphysics of possible worlds, and the latter focuses on semantics aspects of LMR. Finally, we show Lewis reply to objection (a) and that argument (b) could be inserted as an incredulous stare on LMR, and that it consists on a petition principi. / Nessa dissertação defenderemos o Realismo Modal de David Lewis (RML), ou seja, a hipótese metafísica acerca da existência real de uma pluralidade de mundos. A defesa que apresentaremos procura evidenciar o caráter pragmático dos argumentos a favor dessa metafísica dos mundos possíveis. Nesse sentido, aproximaremos a filosofia de David Lewis (1986) a de W. V. O. Quine (1960) e procuraremos mostrar que Lewis utiliza critérios para tomada de decisões ontológicas semelhantes aos defendidos por Quine. Esses critérios são: a simplicidade de formulação, a economia teórica e a desconfiança de critérios meramente intuitivos como guias para a Filosofia. Para cumprir nosso objetivo, estruturamos a dissertação em três capítulos. No primeiro apresentamos benefícios filosóficos do RML que demonstram a utilidade teórica do idioma dos mundos possíveis. Esses benefícios estão relacionados a noções importantes para a Filosofia da Linguagem e a Teoria do Conhecimento tais como: Modalidades, Contrafatuais, e um tratamento uniforme para Propriedades e Proposições. O segundo capítulo divide-se em duas partes. Na primeira traçamos um pano de fundo filosófico que acreditamos estar relacionado à filosofia de Lewis. Compõem esse pano de fundo: um cenário que identificamos como neo-humeano e a retomada de discussões metafísicas na Filosofia Analítica Contemporânea. Na segunda parte apresentamos três teses formuladas por Lewis para garantir a consistência e a coerência de seu Realismo Modal: a Concretude, o Isolamento e a Plenitude. No terceiro capítulo discutimos duas críticas ao RML: (a) David Armstrong & Peter Forrest (1984) e (b) Susan Haack (1977). Cada um desses artigos apresenta uma crítica diferente. A primeira procura identificar um paradoxo na metafísica dos mundos possíveis e a segunda concentra-se em aspectos semânticos do RML. Por fim, mostramos como a objeção em (a) é refutada por Lewis e como o argumento em (b) poderia se inserir no grupo de críticas que Lewis classifica como um olhar incrédulo sobre o RML. Por isso, concluímos que esse olhar consiste em uma petição de princípio.

Objects are characterised by their properties. If an object is a red postbox, then it has the property of being red, and the property of being a postbox. This thesis is an attack on a particular view of the metaphysics of properties, according to which some properties are privileged over others. The most well-known theories of privileged properties are Armstrong’s theory of sparse immanent universals (1979b) and Lewis’ natural properties (1983). According to their supporters, only privileged properties perform certain jobs, such as featuring in laws of nature, or grounding similarity between objects. Metaphysical posits are theoretically virtuous if they can account for a range of different phenomena in a relatively parsimonious manner. The ability of privileged properties to perform a range of worthwhile ‘work’, therefore, is what justifies a belief in them. The conclusion I reach is that a single group of properties is not capable of satisfying the key roles commonly attributed to the privileged properties. Without satisfying these roles in concert, a belief in mainstream versions of privileged properties is not justified. The first part of this thesis is devoted to an explication of privilege and the roles which privileged properties are taken to perform. I conclude that three roles in particular, Supervenience, Similarity and Magnetism are key roles for mainstream theories of privilege. In part two, I show that the properties which satisfy the Supervenience role are not the same as those which satisfy the Similarity and Magnetism roles. In the final chapter of this thesis I discuss the implications of my findings for support for theories of privilege.

Ce mémoire présente une analyse critique de la solution contextualiste de David Lewis au problème sceptique. Pour Lewis, il s’agit d’un problème de possibilités d’erreur à éliminer. En effet, puisque l’on ne peut pas éliminer diverses hypothèses sceptiques, il semble que la connaissance soit impossible. Ce travail est d’abord une présentation du problème sceptique et de la solution que Lewis lui apporte. On verra que son objectif est de rendre compte de la plausibilité de l’argument sceptique tout en protégeant certaines intuitions au sujet de la connaissance. Ainsi, la théorie de Lewis explique quelles sont les présuppositions qu’il est légitime d’entretenir dans les attributions de connaissance. Ces attributions sont les énoncés de type « S sait que P ». On verra que cela prend la forme d’une théorie contextualiste des possibilités d’erreur pertinentes. Ce travail vise ensuite à situer la thèse de Lewis dans la littérature sur le contextualisme épistémique, c’est-à-dire en général, l’idée selon laquelle le contexte de conversation joue un rôle dans la détermination de la valeur de vérité d’une attribution de connaissance. Nous verrons que les solutions contextualistes au problème sceptique peuvent avoir des résultats significativement différents. Enfin, ce travail présentera des critiques importantes sur Elusive Knowledge. Elles prendront la forme d’un retour sur la manière dont Lewis conçoit le problème du scepticisme et celui de l’élimination des possibilités d’erreur. / This thesis is a critical analysis of David Lewis’s contextualist solution to the skeptical problem. The skeptical problem, for Lewis, is a problem of relevant possibilities of error : given that we cannot rule out various skeptical hypotheses, it seems that knowledge is impossible. The first chapter introduces Lewis’s solution to skepticism. We’ll see that his aim is to account for the plausibility of the skeptical argument, while at the same time to protect some of our intuitions concerning knowledge. To that end, Lewis’s solution points to the specific possibilities which can be properly ignored in our knowledge attributions. Knowledge attributions are sentences like « S knows that P. » We’ll see that this explanation takes the form of a contextualist theory about relevant possibilities of error. The second chapter’s task is to locate Lewis’s theory within the literature on epistemic contextualism. Epistemic contextualism, in general, is the claim that the truth value of knowledge attributions is strongly determined by the context of the conversation. But, as this chapter should emphasize, several solutions to skepticism may share the « contextualist » label, while yielding significantly different results. The final chapter will address some important objections to Elusive Knowledge. They are related to the reasons why, according to Lewis, skepticism is a genuine problem for epistemology; on the other hand, they question the notion of elimination of error possibilities.

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Lewisian Genuine Realism (GR) about possible worlds is often deemed unable to accommodate impossible worlds and reap the benefits that these bestow to rival theories. This thesis explores two alternative extensions of GR into the terrain of impossible worlds. It is divided in six chapters. Chapter I outlines Lewis’ theory, the motivations for impossible worlds, and the central problem that such worlds present for GR: How can GR even understand the notion of an impossible world, given Lewis’ reductive theoretical framework? Since the desideratum is to incorporate impossible worlds into GR without compromising Lewis’ reductive analysis of modality, Chapter II defends that analysis against (old and new) objections. The rest of the thesis is devoted to incorporating impossible worlds into GR. Chapter III explores GR-friendly impossible worlds in the form of set-theoretic constructions out of genuine possibilia. Then, Chapters IV-VI venture into concrete impossible worlds. Chapter IV addresses Lewis’ objection against such worlds, to the effect that contradictions true at impossible worlds amount to true contradictions tout court. I argue that even if so, the relevant contradictions are only ever about the non-actual, and that Lewis’ argument relies on a premise that cannot be nonquestion- beggingly upheld in the face of genuine impossible worlds in any case. Chapter V proposes that Lewis’ reductive analysis can be preserved, even in the face of genuine impossibilia, if we differentiate the impossible from the possible by means of accessibility relations, understood non-modally in terms of similarity. Finally, Chapter VI counters objections to the effect that there are certain impossibilities, formulated in Lewis’ theoretical language, which genuine impossibilia should, but cannot, represent. I conclude that Genuine Realism is still very much in the running when the discussion turns to impossible worlds.

Master of Philosophy (MPhil) / Informationist Science Fiction theory provides a way of analysing science fiction texts and narratives in order to demonstrate on an informational basis the uniqueness of science fiction proper as a mode of fiction writing. The theoretical framework presented can be applied to all types of written texts, including non-fictional texts. In "Informationist Science Fiction Theory and Informationist Science Fiction" the author applies the theoretical framework and its specific methods and principles to various contemporary science fiction works, including works by William Gibson, Neal Stephenson and Vernor Vinge. The theoretical framework introduces a new informational theoretic re-framing of existing science fiction literary theoretic posits such as Darko Suvin's novum, the mega-text as conceived of by Damien Broderick, and the work of Samuel R Delany in investigating the subjunctive mood in SF. An informational aesthetics of SF proper is established, and the influence of analytic philosophy - especially modal logic - is investigated. The materialist foundations of the metaphysical outlook of SF proper is investigated with a view to elucidating the importance of the relationship between scientific materialism and SF. SF is presented as The Fiction of Veridical, Counterfactual and Heterogeneous Information.