<p>The purpose of this dissertation is to argue that epistemic contextualism, which proposes that the word ‘know’ is a context-sensitive term, is seriously deficient and therefore indefensible. Since epistemic contextualists claim that their semantic theory of ‘know’ contributes not only to a linguistic model of knowledge ascription but also to a unified solution to some important puzzles in epistemology, I divide my thesis into two basic parts. In the first part (i.e., Chapters 2 and 3), I argue that the proponents of both binary and ternary accounts of the supposed context-sensitivity of ‘know’ fail to provide a reasonable linguistic model of knowledge ascription. My argument in Chapter 1 indicates that ‘know’ cannot be treated as a binary context-sensitive term that is similar to paradigmatic indexical terms or gradable adjectives. Chapter 2 takes contrastivism as a representation of the ternary account of the supposed context-sensitivity of ‘know’ and argues that this theory is in an even worse position because it even fails to capture the supposed phenomena of the context-sensitivity of knowledge ascription. The second part (i.e., Chapters 4, 5, and 6) argues that epistemic contextualism does not provide us with a really satisfactory solution to the puzzles of skepticism, the epistemic closure principle and fallibilism. On the contrary, its rival, invariantism, with some support from pragmatics, psychology of belief and experimental philosophy, is able to solve the above puzzles in a quite nice way. At the end of my thesis (i.e., Chapter 7), I systematize the observations, the evaluations and the critiques of epistemic contextualism from the previous chapters and indicate that epistemic contextualists even fail to establish their supposed phenomena of the context-sensitivity of ‘know.’</p> / Doctor of Philosophy (PhD)

nÃo hà / This thesis aims facing the skeptical argument classic type from the contrastivist knowledge theory. The problem we will approach is when we accept the epistemic logic principle called closing principle. The principle states that knowledge is closed under implication and seems to regulate the way we expand our ordinary knowledge. Basically the closure affirms that for every epistemic subject S, target proposition p and logic Contrary q, If S knows that p and S knows that p logically implies q, so S knows that q. The problem arises when the contrary logic is a skeptical hypothesis, a hypothesis we can't know. Operating a modus tollens in the beginning closure a skeptic concludes logically that we can't know anything. To contextualize the skeptical problem contrastive solution problem that makes uses of closing we will show two theories treatment that will serve as preliminaries. The first is Fred Dretske's Relevant Alternatives Theory and the secondd is David Lewis' Contextualism. Dretske acknowledged accepting closure means surrendering to skepticism, for this reason tried to solve the problem rejecting the closing validity. The Closure rejection by Dretske, however, was considered ad hoc, therefore, unable to solve the problem. David Lewis contextualist solution, however, accepts the closure principle validity and seeks problem resolution by accusing the skeptic of misunderstand as to semantic term know. For Lewis, "knowledge" is an indexical term and , as such, undergoes contextual (semantic and epistemic) variations. Understand adequately the knowledge indexicality, for the contextualist, will show the paradox is only apparent. We will show Lewis theory advantages, but we will also show that it is unsatisfactory to solve skepticism problem. We will defend, finally, that the theory that best accommodates ordinary knowledge against skeptical arguments is Jonathan Schaffer's Contrastivism. The contrastivist theory will look to dodge the problem appealing to an epistemic revisionism. For Schaffer, the knowledge relation is essentially ternary and when we look at the skeptic puzzle by contrastivist bias we will perceive the problem is mitigated, that is, it is weakened in a most intuitive way than Dretske and Lewis theories. The contrastivist theory will defend, in an innovative way, that ordinary knowledge is compatible with skeptical doubt. / Esta tese tem por objetivo enfrentar um tipo clÃssico de argumento cÃtico a partir da teoria contrastivista do conhecimento. O problema que abordaremos surge quando aceitamos o princÃpio de lÃgica epistÃmica chamado princÃpio de fechamento. O princÃpio afirma que o conhecimento à fechado sob implicaÃÃo e parece regular o modo como expandimos nosso conhecimento ordinÃrio. Basicamente o fechamento afirma que para todo sujeito epistÃmico S, proposiÃÃo alvo p e contrÃria lÃgica q, se S sabe que p e S sabe que p implica logicamente q, entÃo S sabe que q. O problema surge quando a contrÃria lÃgica à uma hipÃtese cÃtica, uma hipÃtese que nÃo podemos conhecer. Operando um modus tollens no princÃpio de fechamento o cÃtico conclui logicamente que nÃo podemos conhecer qualquer coisa. Para contextualizar a soluÃÃo contrastivista do problema cÃtico que faz uso do fechamento apresentaremos o tratamento de duas teorias que nos servirÃo de preliminares. A primeira à a Teoria das Alternativas Relevantes de Fred Dretske e a segunda à o Contextualismo de David Lewis. Dretske reconheceu que aceitar o fechamento significa se render ao ceticismo, por esta razÃo tentou resolver o problema rejeitando a validade do fechamento. A rejeiÃÃo do fechamento por Dretske, entretanto, foi considerada ad hoc e, por isso, incapaz de resolver o problema. A soluÃÃo contextualista de David Lewis, entretanto, aceita a validade do princÃpio do fechamento e busca resolver o problema acusando o cÃtico de equivocar-se quanto à semÃntica do termo conhecer. Para Lewis o âconhecimentoâ à um termo indexical e, como tal, sofre variaÃÃes (semÃnticas e epistÃmicas) contextuais. Compreender adequadamente a indexicalidade do conhecimento, para o contextualista, mostrarà que o paradoxo à apenas aparente. Mostraremos as vantagens da teoria de Lewis, mas mostraremos tambÃm que ela à insatisfatÃria para resolver o problema do ceticismo. Defenderemos, por fim, que a teoria que melhor acomoda o conhecimento ordinÃrio frente aos argumentos cÃticos à o Contrastivismo de Jonathan Schaffer. A teoria contrastivista buscarà esquivar-se do problema apelando para um revisionismo epistÃmico. Para Schaffer, a relaÃÃo de conhecimento à essencialmente ternÃria e quando olharmos para o puzzle cÃtico pelo viÃs contrastivista perceberemos que o problema à mitigado, ou seja, à enfraquecido de um modo mais intuitivo do que as teorias de Dretske e Lewis. A teoria contrastivista defenderÃ, de maneira inovadora, que o conhecimento ordinÃrio à compatÃvel com a dÃvida cÃtica.

This work has four aims: (i) to provide an overview of the current debate about the semantics of knowledge attributions, i.e. sentences of the form ⌜S knows that Φ⌝; (ii) to ground the debate in a single semantic-pragmatic framework; (iii) to identify a methodology for describing the semantics of knowledge attributions; (iv) to go some way towards describing the semantics of knowledge attributions in light of this methodology, and in particular to defend moderate invariantist semantics against its main current rivals. Aims (i) and (ii) are largely clarificatory; in §1 I set out a single semantic-pragmatic framework and over the course of this work show that it can be modified to explain and distinguish the various theories of the semantics of knowledge attributions currently on offer. Aim (iii) is also met in §1. I argue that a theory of the semantics of knowledge attributions T must be able to account for at least some ordinary speakers’ intuitions about the felicity or infelicity of utterances of the sentence ⌜S knows that Φ⌝ (felicity intuitions) purely in terms of its semantics. I also identify a number of theoretical considerations about knowledge and argue that if T conflicts with any one of these considerations, we should presume that T is false. Aim (iv) is met over the course of this work. According to moderate invariantism ⌜S knows that Φ⌝ is true if and only if S confidently believes the proposition expressed by , this proposition is true and S’s epistemic position with respect to this proposition meets a moderately high epistemic standard. In §§2 – 5 I argue that the main current rivals to moderate invariantism – attributor contextualism, contrastivism, subject-sensitive invariantism and assessor relativism – conflict with at least one of the theoretical considerations identified in §1. In §6 I argue that moderate invariantism accounts for some ordinary speakers’ felicity intuitions purely in terms of the semantics of ⌜S knows that Φ⌝; I also argue that it is consistent with all of the theoretical considerations identified in §1. Moreover, in §§2 – 6 I argue that no theory is capable of accounting for all felicity intuitions purely in terms of the semantics of ⌜S knows that Φ⌝, and that only moderate invariantism can successfully explain why speakers have all of these intuitions. In §7 I conclude that moderate invariantism correctly describes of the semantics of knowledge attributions, or at least does so better than its main current rivals.

It is widely believed that we have immediate, introspective access to the content of our own thoughts. This access is assumed to be privileged in a way that our access to the thought content of others is not. It is also widely believed that, in many cases, thought content is individuated according to properties that are external to the thinker's head. I will refer to these theses as privileged access and content externalism, respectively. Though both are widely held to be true, various arguments have been put forth to the effect that they are incompatible. This charge of incompatibilism has been met with a variety of compatibilist responses, each of which has received its own share of criticism. In this thesis, I will argue that a contrastive account of self-knowledge is a novel compatibilist response that shows significant promise.