Scepticism, the view that knowledge is impossible, threatens our conception of ourselves as epistemic subjects as much as it endangers our conception of the external world. The book develops a modal account of knowledge and provides an answer to scepticism based on a detailed examination of the main sceptical argument. It discusses prominent contemporary theories of knowledge, in particular safety and sensitivity theories, and shows that they cannot handle Gettier-type examples of a new kind. An alternative analysis of knowledge in terms of relevantly normal possibilities is developed. The sce.