Religious Faith and the Fallibility of Public Reasons

Rawlsian liberals define legitimacy in terms of the public justification principle (PJP): the exercise of political power is legitimate only if it is justified on the grounds of reasons that all may reasonably be expected to accept. Does PJP exclude religious reasons from public justification of legal provisions? I argue that the requirement of 'reasonable acceptability' is not clear enough to answer this question. Furthermore, it fails to address the problematic fact that justification on the grounds of religious faith involves non-negotiable claims, which is incompatible with respect for fellow citizens as colegislators. Accordingly, I reformulate PJP in fallibilistic terms: the exercise of political power is legitimate only if it is justified on the grounds of reasons that can be subject to reasonable criticism. I show that reasons based on religious faith do not meet this principle, just like any other reasons that involve claims about final values.