Rawls had misgivings about the account of stability he gave in A Theory of Justice. It ignored “the fact of reasonable pluralism,” that is, that the social contract has to attract people who disagree about fundamental values of the kind embraced in “comprehensive” doctrines. The contract doctrine welcomes reasonable comprehensive doctrines but forbids the use of state power to promote a comprehensive liberalism, which he confessed he had assumed. There is also a “fact of oppression,” that no state can stabilize itself by imposing a comprehensive doctrine without resorting to the tactics of Torquemada or Stalin. A “liberal principle of legitimacy” forbids this. One must hope for an “overlapping consensus” of reasonable, comprehensive doctrines to settle upon a “political conception of justice.” Rawls’s concessions may lead even further, amounting to a “fact of justice pluralism,” that is, that there are multiple, incompatible, but equally reasonable political conceptions of justice – including ones that reject political equality as Rawls conceives it. Rawls admitted there was a “family” of such conceptions but insisted that each must satisfy a “criterion of reciprocity.” This chapter ekes out Rawls’s published remarks to construct a “reciprocity” argument for fair value, complementing the “stability” argument of Chapter 15.

This essay shows the continued value of Rawls’s public reason project. Its internal tendency is to generate new ideas. To do so, I review seven models of public reason, beginning with A Theory of Justice. Following Political Liberalism, I focus on Rawls’s unaddressed problem of justice pluralism. Rawls did not contain reasonable disagreement abou tjustice. Failing to stop it requires developing a fourth model of public reason. If Rawlsians accept justice pluralism, they must explore Gerald Gaus’s public reason project, so I introduce three models of public reason in Gaus’s work. The final model has only begun to bear fruit, generating a research program Gaus called the New Diversity Theory. Rawls and Gaus show that the public reason project remains a fertile research program