In recent years, issues such as migration, globalization, and ethnic identity have achieved growing political importance at the expense of traditional left/right issues. Ritter argues that this reflects an intensified conflict between nationalism and cosmopolitanism, an ideology committed to universal moral equality and global forms of community. Against this background, Ritter examines the ideas of key cosmopolitan thinkers, arguing that these ideas form a coherent system of thought centered on the organization of diversity, within and between states.