Rawls ( Political Liberalism: Expanded Edition (Columbia Classics in Philosophy) ) admits that the ideal of public reason doesn’t pertain in “private” settings like churches and universities. But, he insists, it “does hold for citizens when they engage in political advocacy in the public forum, and thus for members of political parties and for candidates in their campaigns and for other groups who support them. It holds equally for how citizens are to vote in elections when constitutional essentials and matters of basic justice are at stake. Thus, the ideal of public reason not only governs the public discourse of elections insofar as issues involve those fundamental questions, but also how citizens are to cast their vote on these questions” (p. 215). The test is: “How would our argument strike us presented in the form of a supreme court opinion?” (p. 254).

Michael Sandel ( Liberalism and the Limits of Justice ) sums up this astonishing argument by saying that for Rawls it is “for citizens of a democracy to allow their political discourse about fundamental questions to be informed by moral and religious ideals is no more legitimate . . . than for a judge to read his or her moral and religious believes into the Constitution” (p. 212). And Sandel asks what would be left out of the abortion debate if Rawls’ strictures were observed: no one who believes the fetus a child could try to convince anyone of that claim in public debate; they could not “vote for a law that would restrict abortion on the basis of this moral or religious conviction”; Catholics could discuss the issue in their churches, but could not bring up the argument “in a political campaign, or on the floor of the state legislature, or in the halls of Congress” (p. 212).