This is a two-volume work with entries on individuals who made some contribution to philosophy in the period 1900 to 1960 or soon after. The entries deal with the whole philosophical work of an individual or, in the case of philosophers still living, their whole work to date. Typically the individuals included have been born by 1935 and by now have made their main contributions. Contributions to the subject typically take the form of books or journal articles, but influential teachers and people otherwise important in the world of philosophy may also be included. The dictionary includes amateurs as well as professional philosophers and, where appropriate, thinkers whose main discipline was outside philosophy. There are special problems about the term "British" in the twentieth century, partly because of human migration, partly because of decolonialization and the changing denotation of the term. The intention has been to include not only those who were British subjects at least for a significant part of their lives (even if they mostly lived outside what is now the U.K.) but also people who spent a significant part of their lives in Britain itself, irrespective of their nationality or country of origin. In the first category are included, for instance, a number of people who were born and educated in Britain but who subsequently taught in universities abroad. In the second category are included those who were born elsewhere but who came to Britain and contributed to its philosophical culture.