Almost everything we know depends in some way on testimony. Without the ability to learn from others, it would be virtually impossible for any individual person to know much beyond what has come within the scope of her immediate perceptual environment. The fruits of science, history, geography – all of these would be beyond our grasp, as would much of what we know about ourselves. We do not, after all, perceive that we belong to one family rather than to another – this is something we are told.

Despite the overwhelming importance of testimony, it has been neglected to a large extent in the philosophical tradition. Arguably, this has resulted from a general sense that our other cognitive faculties, such as perception, are more basic and therefore ought to be the primary focus of our investigations. In recent years, however, the idea that testimony is of secondary importance has been forcefully challenged, and new ways of thinking of testimony have been fruitfully explored by a number of philosophers. The present issue of Episteme aims to build on this body of work and to broaden it by incorporating insights from three different groups of people: philosophers who have already done considerable work in social epistemology, philosophers who are for the first time applying their work in other areas of epistemology to testimony, and psychologists who study the development of our ability to learn from others. The papers in this issue, with one exception, were delivered at the fourth annual Episteme conference, held at Rutgers University in June, 2007.