The subject of this book is a unified and distinctive school of British ethical theorists active from the 1870s through the 1950s, though its period of greatest influence was the 1920s and 1930s. The book recovers this neglected school's history, showing what its members thought, how they influenced each other, and how their views changed through time; identifies the common assumptions that made it unified and distinctive; and argues for the superiority of these assumptions over others such as Aristotle's and Kant's.