A classic of today’s German philosophy analyzes the theme of the dialogue of cultures from the angle of three subsequent questions. First, he is explaining why the encounter of cultures matters at the present stage of a crisis-ridden modernity. Within the horizon of an emerging world-society we face different cultural “modernities” which are in each case deeply shaped by the stamp of strong religious traditions. Second, the plural of “modernities” indicates a certain propensity towards cultural fragmentation which is even stimulated by religious fundamentalism. This tendency also calls for an intercultural discourse on principles of political justice as the normative basis for a cosmopolitan order. Such a discourse is to facilitate agreements not only between different cultures and religious traditions, but also across the gap between religious and secular parties, so this raises – third – the question of how to understand secular reason in relation to religion – a challenge for philosophy to reflect upon its own limits without betraying the core of the Enlightenment tradition.