In his first published treatment of public reason, “The Idea of Public Reason,” John Rawls defended an obligation of citizenship he called “the duty of civility.” This duty requires citizens to “be able to explain to one another on those fundamental questions how the principles and policies they advocate and vote for can be supported by the political values of public reason.” More recently, in the essay “The Idea of Public Reason Revisited,” Rawls has qualified the duty with an addendum he refers to as “the proviso.” This “allows us to introduce into political discussion at any time our comprehensive doctrine, religious or nonreligious, provided that, in due course, we give properly public reasons to support the policies and principles our comprehensive doctrine is said to support.”

While the duty of civility and the proviso obviously raise a number of questions, Rawls's basic idea seems clear enough. Participants in public debate may publicly offer arguments for their political positions which are drawn from their comprehensive views. But in a pluralistic society, they should also be aware that not everyone will accept all their premises or regard their arguments as providing good reasons for the policies and principles they favor. They must therefore be ready to make good their religious arguments by supplementing them with what Rawls calls “properly public reasons.”

Rawls's view is a version of what I have been calling “the standard approach.”