Abstract

'Public reason' in Rawls's stipulated usage signifies propositions that can legitimately be used in deliberating on and deciding fundamental issues of political life and legislation because they are propositions which all citizens may reasonably be expected to endorse: their use is therefore fair (respects the moral principle of reciprocity) and preserves the public peace which is at risk from contests between comprehensive doctrines, contests exemplified by wars of religion. This attractive set of suggestions is ruined by irresoluable ambiguities, truncation of reason's resources and of public discourse just when they are most needed, and incipient capitulation to some radical injustices. But public reason may nonetheless be an opportune phrase for conveying the gist of four permanently valid theses in the classical political thought that develops from Socrates/Plato to Aquinas and beyond. That tradition has been significantly modified by recognition that a human right to immunity of religious beliefs and acts from coercion extends – precisely by reason of the importance of finding and adhering to the truth about the divine source of reality and value – to mistaken as well as correct religious beliefs and practices. That immunity is subject to limitations necessary to preserve public order; likewise, a religion's legitimacy as a source of reasons for public actions is dependent on its willingness to foster genuine public discourse. Analogously, a political or legal philosophy's rational warrant is dependent on the compatibility of its theses with the worth of authentic discourse and the support they give to institutions, including the rule of law, which favour such discourse. Habermas's account of discourse ethics fails by overlooking some truths about discourse, truth and friendship that Plato made clear in Gorgias. And (the rule of) law, too, is most adequately understood as a product and articulation of public reason.