Self-defeat and the foundations of public reason

At the core of public reason liberalism is the idea that the exercise of political power is legitimate only if based on laws or political rules that are justifiable to all reasonable citizens. Call this the Public Justification Principle. Public reason liberals face the persistent objection (articulated by, among others, Joseph Raz, Steven Wall, Allen Buchanan, and David Enoch) that the Public Justification Principle is self-defeating. The idea that a society's political rules must be justifiable to all reasonable citizens is intensely controversial among seemingly reasonable citizens of every liberal society. So, the objection goes, the Public Justification Principle is not justifiable to all reasonable citizens, and thus fails its own test of legitimacy. And this, critics conclude, undermines the public reason liberal project. This article argues that answering the self-defeat objection to public reason liberalism requires fundamentally rethinking prevailing accounts of the Public Justification Principle's role. My aim is to develop an account of the Public Justification Principle that vindicates its coherence and moral appeal in the face of reasonable disagreement.