ABSTRACT
This chapter considers the question of what diversity is. It outlines the social gains to which increased diversity is supposed to give rise: on the one hand efficiency gains, on the other hand justice gains (including a reduction in unjust discrimination). The chapter discusses what recent research tells us about how likely these gains are to ensue, and assesses the charge that policies of preference aimed at diversity are themselves forms of unjust discrimination. Most modern societies are made up of individuals with widely differing conceptions of the human good. These conceptions are often embedded within what John Rawls calls a 'comprehensive doctrine', a relatively systematic framework of theoretical and normative beliefs, which may be backed up by a tradition of textual exegesis. Besides being plural in the sense that they contain proponents of different comprehensive doctrines, modern societies are also usually plural in the sense that they contain adherents of different ethno-cultures.
