This thesis offers a reassessment of the philosophical problem of scepticism about knowledge of the external world. It distinguishes between different forms of this sceptical problem and considers two kinds of response: a strategy developed by Tim Williamson, and a disjunctivist approach. Chapters one and two offer an introduction to the problem of scepticism: the sceptical arguments of Descartes and Hume are compared, and Williamson’s approach to scepticism is introduced. Chapter three considers three different ways of responding to Humean scepticism. This chapter offers an interpretation of Stroud’s objection to externalism and considers whether disjunctivist accounts are vulnerable to a similar objection. Chapter four compares Williamson’s approach with one form of disjunctivist account. Central to this discussion is a distinction between responses to scepticism which question whether there is guaranteed epistemic access to one’s own mental states, and a disjunctivist account which proposes that the subject’s perspective on their conscious states is not grounded on a mode of knowing something independent of it. Chapter five considers a further debate about disjunctivism and scepticism. Wright’s objections to disjunctivist accounts are considered, and McDowell’s version of disjunctivism is compared with a Moorean response to scepticism.

My thesis here is that Merleau-Ponty’s ontology of flesh, in its development, suggests a logic of incarnation which carries philosophical ontology beyond entrenched dualisms, and offers to Christian theology a route away from dualistic compromises and back to its own deepest insight. I set out first to develop Merleau-Ponty’s fleshly ontology by tracing its roots in his early thought on the reversibility of perception, which installs the perceiver at the heart of a world with which he is engaged and on which he depends; this relationship is grounded in the elemental faith of perception. I develop this perceptual understanding with reference to eating as a mode of perception; hunger joins our biological needs to their imaginative development, and Man, the hungry animal, transforms his desire, and thus his world. I show how dualistic ontologies are grounded in a geometrical conception of nature which founds a notion of God as removed from the world in the absolute distance of the geometer from geometry, and argue that this mathematisation of nature is hypostasised in the modern understanding of vision. I develop a counter-understanding which liberates the seer from his incarceration in immobility, emphasising that sight depends on movement and on its imbrication with the other senses, involving us in a world of existential significance, and suggesting a partial recovery of the extramission and species theories of sight. I then argue that nature must be understood in terms of place, rather than as a spatiotemporal container. There is a fundamental man-nature chiasm which precedes analysis. Incarnation is not an insertion into nature but a flowering within it of a fundamental logos. This grounds metaphysics in the perceived world, affirming meaning within contingency. For a Christian theology rooted in such a notion of incarnation, God is revealed in the depths of nature and history.

This thesis engages the issue of personhood, arguing that persons are both analogical and dialogical beings. I look at personhood first, from the standpoint of the slandered and 'accused' person. Beginning with the scene of Christ before Pilate, I show that the logic of accusation is unassailably couched within the grammar of testimony or of bearing witness (Chapter 1). Next, I treat the Dreyfus Affair and the contrast of mystique and politique in the writings of Charles Peguy (Chapter 2). Here I tum to the 'accusation in the accusative' logic of Emmanuel Levinas, demonstrating that within an approach of radical alterity to the exclusion of other grammatico-ontological cases, the person becomes lost without some sort of original, analogical case of 'giving' (Chapter 3). In response to extreme accounts slander and of the heterogeneity of the person, this thesis, secondly, proposes that the person should be understood first analogically, and secondly, as an analogical extension, dialogically. To this end I examine the debate concerning analogy in Thomas Aquinas and the tradition that followed him. I explore both the metaphysical path of resolutio, perfection, and theological recapitulation (Chapter 4), and then look to the debate on analogy itself arguing that it is best understood as pointing toward an analogia entis that is coextensively an analogia personae (Chapter 5). Finally, I conclude with an articulation of the person as dialogical. I look first to the form of dialogue in Plato, then I conclude with three sections enacting a 'call and response' of the divine persons speaking 'to the creature through the creature', where I end with an account of persons living a dialogically ensouled life within the communio personarum (Chapter 6). I finish with a brief conclusion recapitulating the argument with a Christie entreaty toward the neighbor.

This document is written from the perspective of the Oasis Link community, a group of dissidents who have resettled in the Mojave Desert sometime in the near future. It is a speculative design document. Surface is what is visible. It’s the crust of the earth and the face of a meteorite—the coat of a jackrabbit and the waxy skin of a Mojave Prickly Pear. Surface is superficial, but it also reflects and defines the underlying structure of something—it makes the hidden visible.

This thesis explores Heidegger’s philosophy of Being and Nothing in the context of the problem of nihilism. Nietzsche diagnosed the present age as an age of nihilism in the sense of a ‘devaluation of the highest values’. Heidegger argues that Nietzsches’s diagnosis suffers from a fundamental failure to question the meaning of ‘nihil’ in ‘nihilism’. This failure is, according to Heidegger, shared by the history of metaphysics which Nietzsche brings to completion, and it is closely connected with the failure of metaphysics to address the question of Being as such. We shall examine the emergence of Heidegger’s early phenomenological approach to the question of Being in his engagement and confrontation with Husserl’s phenomenology, and trace its subsequent development in major writings of his. It will be argued that Heidegger’s philosophy of Being permits for the first time a more adequate understanding of the problem of Nothing. Throughout the thesis, the horizon of the discussion is the question of the meaning and the ground of nihilism, which will also be addressed explicitly through an examination of Heidegger’s confrontation with Nietzsche.

With the recent move to multi-core architectures it has become important to create the means to exploit the performance made available to us by these architectures. Unfortunately parallel programming is often a difficult and time-intensive process, even to expert programmers. Auto-parallelisation tools have aimed to fill the performance gap this has created, but static analysis commonly employed by such tools are unable to provide the performance improvements required due to lack of information at compile-time. More recent aggressive parallelisation tools use profiled-execution to discover new parallel opportunities, but these tools are inherently unsafe. They require either manual confirmation that their changes are safe, completely ruling out auto-parallelisation, or they rely upon speculative execution such as software thread-level speculation (SW-TLS) to confirm safe execution at runtime. SW-TLS schemes are currently very heavyweight and often fail to provide speedups for a program. Performance gains are dependent upon suitable parallel opportunities, correct selection and configuration, and appropriate execution platforms. Little research has been completed into the automated implemention of SW-TLS programs. This thesis presents an automated, machine-learning based technique to select and configure suitable speculation schemes when appropriate. This is performed by extracting metrics from potential parallel opportunities and using them to determine if a loop is suitable for speculative execution and if so, which speculation policy should be used. An extensive evaluation of this technique is presented, verifying that SW-TLS configuration can indeed be automated and provide reliable performance gains. This work has shown that on an 8-core machine, up to 7.75X and a geometric mean of 1.64X speedups can be obtained through automatic configuration, providing on average 74% of the speedup obtainable through manual configuration. Beyond automated configuration, this thesis explores the idea that many SW-TLS schemes focus too heavily on recovery from detecting a dependence violation. Doing so often results in worse than sequential performance for many real-world applications, therefore this work hypothesises that for many highly-likely parallel candidates, discovered through aggressive parallelisation techniques, would benefit from a simple dependence check without the ability to roll back. Dependence violations become extremely expensive in this scenario, however this would be incredibly rare. With a thorough evaluation of the technique this thesis confirms the hypothesis whilst achieving speedups of up to 22.53X, and a geometric mean of 2.16X on a 32-core machine. In a competitive scheduling scenario performance loss can be restricted to at least sequential speeds, even when a dependence has been detected. As a means to lower costs further this thesis explores other platforms to aid in the execution of speculative error checking. Introduced is the use of a GPU to offload some of the costs to during execution that confirms that using an auxiliary device is a legitimate means to obtain further speedup. Evaluation demonstrates that doing so can achieve up to 14.74X and a geometric mean of 1.99X speedup on a 12-core hyperthreaded machine. Compared to standard CPU-only techniques this performs slightly slower with a geometric mean of 0.96X speedup, however this is likely to improve with upcoming GPU designs. With the knowledge that GPU’s can be used to reduce speculation costs, this thesis also investigates their use to speculatively improve execution times also. Presented is a novel SW-TLS scheme that targets GPU-based execution for use with aggressive auto-parallelisers. This scheme is executed using a competitive scheduling model, ensuring performance is no lower than sequential execution, whilst being able to provide speedups of up to 99X and on average 3.2X over sequential. On average this technique outperformed static analysis alone by a factor of 7X and achieved approximately 99% of the speedup obtained from manual parallel implementations and outperformed the state-of-the-art in GPU SW-TLS by a factor of 1.45.

In this thesis I argue that we should break with the dominant Kripkean tradition concerning natural kind terms and theoretical identity. I claim that there is just no interesting connection between the metaphysics and semantics of natural kind terms, and demonstrate this by constructing a version of descriptivism that is combined with the same metaphysics – that is, a nontrivial version of essentialism – found in Kripke, but which effectively avoids all of the standard criticisms. With my version of descriptivism in place, I present what I take to be the most reasonable version of metaphysical essentialism, positing only what I call 'thin' essences. I claim that thin essences are perfectly adequate to underpin scientific realism, and moreover that they are sufficient to support the version of descriptivism developed here. In effect, what I offer here is an error theory of the Kripkean tradition: Kripke is right to think that there are interesting things to say about meaning and essence, but just wrong about what those things are. Thus whilst Kripke thinks that it is possible to make discoveries about the meanings of natural kind terms, I think, rather, that we make empirical discoveries that lead to revisions in meaning. Furthermore, whilst Kripke thinks there is a dichotomy between de re and de dicto necessity, and that theoretical identities are necessary de re, I think this distinction is both misleading and inaccurate, and that the necessity of theoretical identities is neither entirely de re nor entirely de dicto. By separating and insulating questions concerning meaning from questions concerning essence I show that whilst scientific discoveries are contingent and a posteriori, the definition of scientific terms are both necessary and a priori.

This thesis investigates the development of ontology as a philosophical discipline in the German philosophical tradition. It starts from what can be considered the invention of ontology and proceeds to the way it was received in the philosophy of Hegel. It is separated into two parts. The first part argues that what can be called the ‘traditional’ form of ontology is developed by Christian Wolff in his 1730 monograph Philosophia prima sive Ontologia, and it traces both the history of the name (or concept) ‘ontology’, as well as the history of the conception which led to Wolff’s formulation of it. The history of the name tracks the use of the concept ‘ontology’ from its first occurrence in 1606 up to Wolff. The history of the conception tracks the conceptions of various philosophical disciplines, found in thinkers such as Aristotle, Aquinas, and Spinoza, that ultimately give rise to Wolff’s conception of ontology as a science of an entity qua entity. The second part traces the development of this Wolffian conception through the philosophical systems of Kant and Hegel. The aim of this thesis is to argue that Wolff’s philosophy should be seen as the original formulation of the philosophical discipline of ontology and that the Wolffian conception of ontology is the one shared by subsequent German thinkers up to, and including, Hegel. I refer to this shared understanding of what ontology is as ‘the German ontological tradition’. The title of the thesis, The Possibility of Ontology, refers to the way in which this traditional understanding of what ontology is, is treated throughout the German ontological tradition. Specifically, Kant argues that the traditional conception is effectively impossible, while in Hegel one can find arguments that are intended to show that some aspects of this traditional discipline are in fact possible. Besides focusing on a fairly under-researched topic of the early history of ontology as a philosophical discipline, this thesis attempts to utilise its historical findings in order to provide novel ways in which the systems of the thinkers such as Kant and Hegel can be understood. There is a serious disregard for, or underplaying of, the Wolffian influence on the philosophical thought of Kant and Hegel, and it is my aim to contribute to the rectification of this situation by demonstrating the frequently overlooked dialogue these thinkers had with Wolff’s conception of ontology.

In this thesis I take the basic idea of self-deception to be that of believing something against good evidence to the contrary because you want it to be true. I then identify the central theoretical problem concerning this phenomenon as being that of giving an account of the explanatory connection between the desire and belief in real life cases of this sort. The two main approaches to answering this question in the philosophical literature are traditionalism and deflationism. Traditionalists hold that the desire leads to the belief by motivating the subject to intentionally acquire the belief, a belief he/she initially knows to be false/unwarranted (i.e., it motivates her to intentionally deceive herself), while deflationists deny this. I defend a deflationary account of how self-deceivers end up with their unwarranted beliefs, but one which differs from other deflationist accounts, either in substance or in emphasis, by trying to preserve a central role for agency and intentional action in the explanation and by trying to elucidate the nature of these culpable actions and intentions. Accordingly, an account is developed which holds that self-deceivers end up self-deceived because of their own actions, actions motivated by the relevant desires and emotions, though these actions are not done with an intention to deceive oneself. I try to show how an account of this sort can explain features of self-deception which any such account would be expected to explain, and in a better way than its rivals, including, for instance, the tension of selfdeception, and the fact that self-deceivers are responsible for their own self-deception, while also avoiding the paradoxes that afflict other agency-focused approaches.

The following is a study of Jean-Paul Sartre’s ontology of conscious awareness. Ontology, for Sartre, consists in the delineation of the constituent elements, structures and dimensions of Being as well as the way in which such constituent features interact within the ekstatic dynamics of the lived experience of the being for whom such ontological features are capable of becoming phenomena of possible awareness. Sartre’s methodology, then, is manifold. The ontological project which Sartre undertakes to develop is at once transcendental, phenomenological and dialectical. It is transcendental inasmuch as it is a theory of the way in which phenomena become experientially possible for a being whose primary existential mode of conscious awareness is as an act of immanent self-relation, as pure auto-affection, and is capable of divesting itself of its modality of active self-affective immanence in constituting for itself a particular phenomenon transcendent to itself. This is to say that what Sartre refers to as pure or transcendental consciousness is capable of dissolving its primordial mode of autoaffective immanent self-awareness in the intentional (or, attentional) act whereby a choice is made to privilege a given phenomenon from amongst the otherwise undifferentiated multiplicity of the conscious existent’s (auto-)affective conscious awareness in order to become conscious of something which is not itself and from which the act of consciousness differentiates itself as not being, whether this privileged phenomenon is ekstatic or extensive, whether it is chosen from the otherwise undifferentiated virtual multiplicity of this conscious existent’s own psychic pastness (or possible future) or from the indifferent multiplicity of worldly actuality. In either case, whether the privileged phenomenon of intentional awareness is egological or material, of the psyche or of the world, the noematic correlate of conscious attention (the explicit or thetic phenomenon of intentional awareness) is transcendent to transcendental consciousness. It is in the investigation of such phenomena that Sartre’s ontology manifests itself as phenomenological. However, for Sartre, such awareness is by no means static, and it is through the ekstatic dynamization of the constituent features of conscious awareness that the transcendental and phenomenological methodologies of Sartre’s ontology of lived experience ultimately prove to be dialectical. Every moment of conscious awareness must, for Sartre, be both surpassed and preserved. Every moment of awareness, with its transcendent dimensions of virtuality and actuality and the auto-affective immanence upon which they depend, reveal themselves as intimately related, then, to memorial dynamics, dynamics which Sartre did little to explicitly develop but upon which an adequate understanding of his ontology depends and which will ultimately ground any investigation of what we might call an existential epistemology.