In his recent work, The Significance of Philosophical Scepticism, Barry Stroud proposes to carry out an in-depth critique of the attempt by philosophers to invalidate all knowledge of an external world on the basis of Descartes' dream argument. His more particular aims in this endeavour are to uncover significant features of any such scepticism and to disclose in the process fundamental aspects of ‘human knowledge’ itself. Thus, among other features of knowledge that his study discloses, he thinks, is, echoing Kant, the idea ‘that a completely general distinction between everything we get through the senses, on the one hand, and what is true or not true of the external world, on the other, would cut us off forever from knowledge of the world around us.’ And a significant feature of Cartesian dream scepticism he believes to have uncovered is that its ‘effectiveness’ rests upon the philosopher's traditional assumption of an objectively existent world that is understandable ‘from a detached “external” viewpoint.’