The idea of public reason — as well as the contraposition among public reason and private reasons — is strictly linked to the rise of pluralistic societies, societies in which the main problem is probably that of finding a lowest common denominator between different and often conflicting reasons. In a nutshell, the public reason is (or should be) just the core of principles and values shared by all the different philosophical and political doctrines. This paper is mainly focused on the very well-known conception of public reason developed by John Rawls as from the publishing of Political Liberalism.
The aim of the first half of this paper is that of pointing out some serious difficulties connected with Rawls’ originary defence of public reason. In particular, in Political Liberalism Rawls assumes, without looking after to find some compelling evidence, that in pluralistic societies like ours the only way for understanding each other is that of constraining public debates and deliberations within the boundaries fixed by public reason, renouncing to deploy the whole truth. In this way, Rawls lays himself open to the critics of not taking seriously the freedom of speech. Furthermore, I argue that public reason is not able to ban comprehensive doctrines, either philosophical or religious, from public debates.
In the second half of the paper, it will be argued for a "soft", more convincing, idea of public reason. In brief, the conception of public reason as "barrage" against all the reasons exceeding a political conception of justice will be replaced by the conception of public reason as "common denominator" or "translator" of these reasons.