Materialism is the view according to which a zombie world is metaphysically impossible. Assuming that zombies are conceivable in the sense that we cannot rule out a priori that our world is a zombie world, materialists must hold that a zombie world is metaphysically impossible despite being conceivable. There are no good reasons to think that this view (type-B materialism) is false, since there are no good reasons to think that the corresponding phenomenal and physical/functional concepts cannot be distinct concepts (...) of the same thing. Nonetheless, we cannot understand how type-B materialism can be true. We cannot understand this, because we cannot in principle explain how a zombie world could be impossible despite being conceivable. (shrink)

I assume that there exists a general phenomenon, the phenomenon of the explanatory gap, surrounding consciousness, normativity, intentionality, and more. Explanatory gaps are often thought to foreclose reductive possibilities wherever they appear. In response, reductivists who grant the existence of these gaps have offered countless local solutions. But typically such reductivist responses have had a serious shortcoming: because they appeal to essentially domain-specific features, they cannot be fully generalized, and in this sense these responses have been not just local but (...) parochial. Here I do better. Taking for granted that the explanatory gap is a genuine phenomenon, I offer a fully general diagnosis that unifies these previously fragmented reductivist responses. (shrink)

In the recent metaphysics literature, a number of philosophers have independently endeavoured to marry sparse ontology to abundant truth. The aim is to keep ontological commitments minimal, whilst allowing true sentences to quantify over a vastly greater range of entities than those which they are ontologically committed to. For example, an ontological commitment only to concrete, microscopic simples might be conjoined with a commitment to truths such as ‘There are twenty people working in this building’ and ‘There are prime numbers (...) greater than 5.’ I argue that a significant challenge to this project comes from the philosophy of mind. As Theodore Sider has pointed out, anti-physicalism is consistent with a sparse ontology. However, I will try to show that the premises of the standard anti-physicalist arguments can be used to form an argument to the conclusion that sentences which quantify over subjects of experience ontologically commit us to subjects of experience. Truths about consciousness cannot be bought more cheaply than their superficial grammar suggests. (shrink)

In this dissertation, I evaluate whether conceivability can be regarded as an epistemic guide to possibility.