Is it possible to establish - establish persuasively - liberal political principles and institutions on the basis of values that are non-controversially shared between different metaphysical and social outlooks? I raise the question apropos of a piece by Martha Nussbaum. Writing about John Rawls, she gives a highly compressed account of the central notions in A Theory of Justice and Political Liberalism. In connection with the latter, Nussbaum says:
Rawls... urges that we must not attempt to ground political principles in any doctrines, whether metaphysical or epistemological or religious, that are controversial among the religious and secular views of life that reasonable citizens hold. So, for example, we would be ill advised to base our political principles on the idea of the immortal soul, or the idea of "self-evident" truth, since many citizens do not accept such ideas. We can, however, Rawls thinks, argue for political principles in a thinner way, using ethical notions that are not inseparable from controversial religious doctrines.
Political principles, so understood, will not be separate from the rest of what religious and secular citizens believe. Instead, they will constitute a realm of overlap among all the "comprehensive doctrines" in the envisaged society - at least all those that are "reasonable," by which Rawls means willing to respect the equal dignity of all citizens.
But if we understand 'the equal dignity of all citizens' in a way compatible with what political liberalism is thought to entail, that is not a framework neutral as between the various metaphysical and social doctrines, religious and secular, that rub shoulders in the public domain. It harmonizes with some better than with others, and with yet others - for example, those encompassing the unequal dignity of different types of people - it harmonizes hardly at all. Liberalism is better as a political framework, not because it is neutral (as between competing outlooks), but because it is better. It needs to be argued and fought for on that basis. (Thanks: MA.)