Finding descriptive titles for books devoted to central issues in philosophy can often become a problem; it is very difficult to be original. Thus the title that I have given to this book is far from novel, having already been used several times by other authors. Nevertheless, I think that I can fairly claim to have employed it in a way that no one else has done before. Concerning my subtitle, some comments are in order. I have added it to emphasize my views regarding the nature and scope of epistemology. In particular, I wish to draw attention to the fact that I conceive its subject matter quite broadly. Rather than equating it, as is often done, with "theory of knowledge," I believe that epistemology should concern itself with the philosophical investigation of human belief in general. The two categories of human belief of most importance to the epistemologist are knowledge and what I shall call in the book "reasonable belief. " In my opinion a complete epistemology must take account of both, attempting to resolve the problems that are peculiar to each. For reasons that I give in the book I believe that knowledge and its problems must be the first concern of the epistemologist. Only after he has developed a satisfactory theory of knowledge can he tum, with any hope of success, to the formu lation of a theory of reasonable belief.