Finding an appropriate means of justifying the fundamental laws that regulate the functioning of constitutional democracies presents a conundrum for contemporary political and legal theory. The politics of these democracies are riven by disagreements that stem from the multitude of competing “comprehensive doctrines” that proliferate in their “background cultures”. A prominent response to this pluralism comes from political liberals who reject the proposition that justification should be based upon the truths embodied in such doctrines, arguing that these cannot be shared by partisans of competing worldviews. Proponents of natural law theory, which offers its own account of the obligation to obey laws, constitute one such group. But liberals consider the doctrine to be just one among many. Yet, despite the diversity of moral views, political liberals believe they have succeeded in building an account able to justify laws to all citizens. They endeavour to accommodate even those citizens who do not adhere to the liberal creed but to other reasonable comprehensive doctrines.
The political liberalism of John Rawls is the best-known example of the consensus version of public reason liberalism. With the inclusion of the convergence variant – a distinction which will be briefly explained below – public reason liberalism may be seen as one of the most recent – and currently the most influential – offspring of the liberal tradition. The family of public reason views offers the liberal principle of public justification as an answer to the pivotal question of what justifies coercion…