In this dissertation, I confront a problem in the philosophy of language from an historical and systematic standpoint. The problem consists in explicating a concept of nonsignificance which can apply, inter alia, to the appraisal of philosophical assertions as category-mistaken or typeabsurd. Such appraisals often take the form: "To say 'a is F' is non-significant, because a is not the ~of thing which can be For not-F." Accordingly, the thesis begins in an examination of the historical and philosophical basis for Russell's theory of logical tvpes, with its concomitant classification of propositions into true, false or nonsignificant. In Part I, I seek to remedy a failing in past exegeses of the development of Russell's type theory which ignore Russell's demand that his "proper" solution to the paradoxes--the ramified theory of types-not simply provide a consistent logicist system; but should also be recommended by his other philosophical doctrines. I remedy this failing by showing that: (i) the source of inconsistency in Frege's logicism lies in his underlying semantic doctrines: complete definition and the treatment of extensions as objects; (ii) the genesis of Russell's ramified theory lies in his logic, epistemology and theory of meaning--viz: the connections between his Vicious Circle Principle, his Multiple Relation Theory of judgement, and his doctrine of incomplete symbols. (iii) in particular, the Multiple Relation Theory provided Russell with a foundation for the ramified theory which was undermined when Wittgenstein subjected it to two "paralysing" objections (hitherto, only partly reconstructed), within Wittgenstein's ongoing critique of the logical doctrines of PM. I reconstruct these criticisms and survey, in general, the critical background to the ramified theory resulting in the changes from the first to the second editions of PM. In concluding Part I, I anticipate the constructive enterprise of Part II in arguing that previous attempts to extend the application of type theory to meaningful predication as a whole have often failed through their insensitivity to contextual relativity and linguistic creativity. Nonetheless, I discuss two accounts--Wittgenstein's theory of formal concepts and Ryle's theory of categories--having features which I preserve in Part II. In addition, I argue against construing category-mistakes as ungrammatical or as false. My general contention through Part II is that category-mistaken significance-failures are best explicated within a theory of linguistic acts (broadly Austinian) . I support this contention by considering the circumstances of an utterance failing to yield a statement in context through its failure to express 'content' to an audience. This notion of 'content' is developed by recourse to those techniques of formal semantics which provide an articulation of structural and algebraic features of contexts, utterances and speech-acts in the interaction of which significance is appraised. The interpreted formal languages I develop borrow features from significance and context logics given in Routley and Goddard's The Logic of Significance and Context, (1973); though my approach to the semantics diverges markedly from theirs. The semantic structures I develop are recommended by their exhibiting systematic relations beaveen utterances, contexts and significance without demanding that category-mistaken predications be diagnosed on the basis of~ priori allocations to categories. They represent a category-mistaken predication in terms of a conflict between conditions for successfully talking about items of a type or sort, and for making a statement of such items, in context. Only in this way, it is argued, can a philosophical theory of meaning accommodate fully the richness, creativity and diversity of linguistic acts in context. / Thesis / Doctor of Philosophy (PhD)

This dissertation examines a traditional philosophical problem within a novel framework. The so-called "problem of the external world" is a problem about how knowledge, and even reasonable belief, about the world are possible, and it is best characterized as the challenge to show how and why scepticism about the external world -the absurd view that such knowledge is impossible -is incorrect. My framework for the examination of this problem involves two major elements. The first element involves a general characterization of the nature of "perennial" philosophical problems, like the problem of the external world, that attempts to isolate the specific features that render them problematic, which, in turn, isolates what is required for their solutions. Applying this characterization to the problem of the external world, the second element of the framework involves distinguishing between two approaches for the solving of the problem, which I label "constructive" and "deflationary," and establishing why the latter approach is preferable. I further distinguish between two general types of deflationary approaches -"therapeutic diagnosis," and "theoretical diagnosis''' -and examine in detail what I take to be the major representatives of each strategy. In the process I offer novel critical interpretations of the work of G.E. Moore and Ludwig Wittgenstein, as well as some of the first detailed critical discussions of recent responses to scepticism by Hilary Putnam and Michael Williams. My general aim is to assess the strengths and weaknesses of both deflationary approaches as responses to scepticism. I argue that all of these attempts to solve the problem are unsatisfactory, and that the challenge to show why scepticism about the external world is incorrect has not yet been met. However, and this is perhaps the most important contribution of the dissertation, I hope to have shown where we should and should not look to meet the challenge. / Thesis / Doctor of Philosophy (PhD)

Scepticism, taken as a challenge to the possibility of justifying knowledge claims in general, has a history perhaps as long and varied as attempts to construct positive theories of knowledge. The relation that holds between scepticism and the rest of epistemology is often assumed to be straightforwardly adversarial. However, in light of the widespread "end or transformation" debate within epistemology in recent decades, the proliferation of sophisticated scholarship concerning scepticism and justification may be taken as a prima facie endorsement of the continuing vitality of traditional epistemology. The publication in 1984 of Barry Stroud's The Significance of Philosophical Scepticism, focused interest in the epistemological community on the burden of specifically modem (global, post-Cartesian, external world) scepticism. However, during the overlapping two decades since Significance, the influence of Richard Rorty's work (particularly Philosophy and the Mirror of Nature published in 1979) has led to a growing suspicion that epistemology has neither a stable nor defensible mandate. In this thesis, I try to connect the two discussions in a novel way, by arguing that the metaphilosophical problems arising from the stalemate I diagnose in the vibrant contemporary scepticism debate does not suggest that epistemology as a discipline is robustly healthy. I characterize metaphilosophical issues as a cluster of concerns involving the methodology, nature, aim, self image and criteria of satisfaction of doing philosophy. Most generally, metaphilosophy is a philosophical exploration of the nature of philosophy; more specifically, it deals with the expectations and aspirations of inquiry. David Hume is rightly remembered as a thoughtful exponent of the power of sceptical reasoning. More recently, he has been recognized for his influential attempt to develop a naturalistic theory of belief that serves to explain how we form and tenaciously cling to our most deeply held beliefs-despite our inability to rationally justify them. I contend that there are metaphilosophical lessons to be learned from Hume's struggle to maintain and defend the theoretical invulnerability of scepticism, despite his evident discomfort adjusting to the potential consequences of such a position. Michael Williams has been an insightful critic of the "pessimism" that he detects in the work of Stroud and "the New Humeans." I outline the major issues in his exchange with Stroud, and evaluate the strengths of each position. I also argue that Williams' "contextualism" fails to rescue epistemology in any substantial way from the fundamental sceptical challenges that can be raised. For each of the central philosophers under consideration (David Hume, Barry Stroud, and Michael Williams), I construct an account of what I call their criteria of satisfaction. The specific classification of particular criteria is much less important here than the metaphilosophical lesson that I extract from the nature of the frequent clashes between different epistemologist's favoured criteria. Into the contemporary debate about modem scepticism, I introduce ancient sceptical concerns like the "problem of the criterion" and the Five Modes of Agrippa, which serve to illustrate the importance of long-standing sceptical metaphilosophical considerations for this discussion. I contend that these ancient problems can help clarify the nature of the contemporary stalement in the debate about modem scepticism. Even if epistemologists become dissatisfied with what they take to be the criteria of satisfaction of the traditional project, motivating the adoption of revised criteria of satisfaction will still encounter grave difficulties. Finally, I discuss possible morals to be drawn from the wider metaphilosophical concerns. I ultimately argue that the remarkably active state of contemporary literature about scepticism should not be mistaken as a straightforward positive indicator of the continued health of philosophical theories of knowledge. To the contrary, an examination of the metaphilosophical issues surrounding scepticism reveals even more urgent problems with the inherent variability and instability of epistemic criteria of satisfaction. An exploration of these issues threatens to lead if not to metaphilosophical scepticism, then at least to a thorough reevaluation of the nature and self-image of the epistemological project. / Thesis / Master of Arts (MA)

This thesis is a criticism of the theory in the philosophy of mind known as "eliminative materialism". While this theory has been advocated by a number of philosophers, none have pressed its thesis harder than Paul Churchland. Consequently, Churchland's work in this area has been the focus of current debates in the philosophy of mind. Although several philosophers have developed significant objections to Churchland's formulation of the thesis, Churchland has always been ready with a convincing reply. For this reason I propose to attack Churchland on as fundamental a level as seems possible, namely, by questioning his prE~supposition that folk-psychological explanation is a species of causal explanation. Without this presupposition there is little reason to expect Churchland's proposed theoretical elimination of folk psychology by neuroscience; for folk-psychological explanation (principally, reasongiving) must be characterized as a species of causal explanation if it is to be replaced by a better causalexplanatory theory of behaviour. I argue that reason-giving explanations are not a species of causal explanation. By undermining one of the central presuppositions of eliminative materialism, I hope to cast sufficient doubt on Churchland's thesis. / Thesis / Master of Arts (MA)