Popper's original vision of the open society is criticized as being, in a certain sense, utopian. Discussion alone will not resolve fundamental political differences, particularly where those differences bear on the premises of liberalism itself. It is noted that Popper later presented a more nuanced view of openness and liberalism, one which sees these concepts as embedded in a tradition of political thought and practice, and in a substantive and not merely a procedural political world view. New problems for the application of this world view in Western democracies are raised by the growth in recent decades of significant groups within Western societies who do not share its assumptions. Possible responses on the part of defenders of the open society to this new situation are considered.