INTRODUCTION In Chapter I, I suggested that there is an understanding of the work of the ancient Greek sceptics which takes them to be realists about the world of material objects and about the minds of others. This is a realism that is undermined by the philosophical work of Descartes. Of course, Descartes is also a realist about the world of material objects and the minds of others, but his conception of a subject and of an object is such as to make a subject's knowledge of the world of objects difficult - if not impossible - to come by. Descartes and his followers may be realists, but it is a realism that brings in its wake various radical sceptical questions. Indeed, several philosophers have insisted that this realism and this scepticism are made for each other. Thus, we find Thomas Nagel claiming that 'realism makes skepticism intelligible', and Colin McGinn writing that 'a prima facie vulnerability to ... a [sceptical] challenge should be regarded as an adequacy condition which any formulation of realism is required to meet' .1 I shall refer to the realism that allows for such radical scepticism as 'hard realism'. According to this variety of realism, the world consists of mind-independent objects whose existence can be thought of from a God's eye perspective, that is, a perspective external to the minds of men (or any other thinking creature).