In this paper, I am going to consider the important idea of public reason,
which has associations with many other ideas of ethico-political
importance – e.g. those of legitimacy and obligation. Crudely, this
idea demands, at least in principle, that no collectively binding coercively
enforced system of social arrangements is legitimate, and
hence morally obligates citizens to conformity with its requirements,
unless it is reasonable from every point of view.