Abstract

This dissertation consists of three essays on philosophical topics. The first is an examination of David Lewis's influential case for the thesis that mental states are physical states. This essay concludes that even if mental states are physically constituted, they are not identical with physical states. The second essay responds from a classical point of view to the challenge in the work of Michael Dummett to classical logic by showing how a semantical anti-realist can justify classical inferential practices. The third essay examines the nexus between scepticism, action, belief and justification. It consists of three parts. The first part takes issue with an argument which is often raised against philosophical scepticism---the argument that scepticism is self-refuting. I take issue with that claim. But also argue that even if it were self-refuting, that is not the same as self-defeating. Indeed the dialectial character of scepticism means that it can be quite powerful even if its arguments are self-refuting. In the second part I examine to what extent the view that the wise man has no beliefs can be attributed to the ancient sceptics. In the third section I examine the way Hume sees sceptical reflections as undermining the nexus between belief and justification