Public Reason

The starting point of Political Liberalism is the recognition that free exercise of reason inevitably leads to a diversity of incompatible comprehensive doctrines — different religions, metaphysical views, and conceptions of the good life. This is not a failure but the natural outcome of liberty. The question is how a just society can be stable when its citizens disagree so deeply about the fundamentals.

Public reason requires that political justifications for constitutional essentials and basic justice be given in terms that all reasonable citizens can in principle accept — not in terms of comprehensive doctrines they reject. A politician who argues for a particular law solely on the basis of Scripture, or solely on the basis of a philosophical doctrine that many reject, fails the test of public reason, even if the conclusion is correct.

Rawls allows comprehensive doctrines to enter public political debate provided that, in due course, citizens are willing to offer a public reason translation of the same conclusions. This "proviso" permits religious voices in democratic politics — indeed, Rawls credits abolitionism and the civil rights movement as examples of religious argument in service of public reason values — while insisting that the ultimate justification must be accessible to all.

Public reason is the central topic of the Introduction and Lecture VI of Political Liberalism (1993); Rawls revisited and expanded it in "The Idea of Public Reason Revisited" (1997).