Most modern and postmodern systems of political ethics presume that humans will not all share a single conception of ultimate happiness or of the best form of life. But more importantly, it is commonly held that it is reasonable for humans to disagree on the best way to live and that justice, therefore, must not be founded on the identification of the ultimate human good but on what humans are entitled to in political and social life. Since the good is a matter of reasonable disagreement, and many forms of good lives can be pursued within a single society, modern liberal theory paradigmatically asserts that what we owe each other takes priority in law and politics over what we owe ourselves in matters of political justice (or what is sometimes referred to as the “priority of the right over the good”). Such theories thus seek to ground accounts of social goods and contracts on a rational basis that does not rely on a single, shared conception of the purpose and meaning of life, such as that of a faith tradition. Of course, many ethical projects in post-Enlightenment modernity—from Marxism to recent revivals of natural law—do not yield to such constraints. But theories that prioritize the protection of individual and group rights and religious and cultural freedom, and that trust in individuals’ capacities to develop and validate their own conception of the good, are characteristic of modernity.

But the commitment to pluralism results in well-known paradoxes or dilemmas. How valuable are liberal rights or autonomy if they do not contribute to some particular kind of well-being? Is it possible to take sides in the defense of bodily and intellectual autonomy without taking sides in the dispute between the truth or falsity of certain doctrines? Can there be a common public account of why political life should prioritize the right over the good, given the commitment that many have to the truth of their ethical and metaphysical doctrines? Can the reasonableness of pluralism be articulated without a positive declaration of skepticism about knowledge of the good?

There is a core problem that we cannot simply sidestep: shared political life requires some consensus about which differences amongst humans we should struggle to remove from the world and which we should accept as likely to be enduring for good reasons. We cannot avoid inquiry into which moral and intellectual differences are reasonable and which are not. For example, two persons who agree that race is morally arbitrary, and that thus we must struggle for a world without racial supremacy, might disagree about whether social differences based on gender should be allowed to persist. Similarly, two persons who agree that political struggles over what justice and welfare require are inevitable because of the social embeddedness of reason might disagree on whether revealed religion is so manifestly contrary to reason that the world would be a better place if religion faded away.

This, in brief, is the problem of “reasonable pluralism.” It is the difference between mere toleration and reciprocal recognition. We tolerate what we find distasteful or even immoral, but we recognize and accept what we find valuable. But there are some puzzles here. How do we understand what lies between disapproval and full acceptance? Indifference is one possibility: I do not tolerate your taste in footwear, nor do I value it; I am simply indifferent to it. But that is not the case with areas of common concern: I am not at all indifferent to your opinions on health-care policy or the new legislation to cut taxes. What then determines whether I regard views contrary to my own as dangerous and wrong, but not criminal, and therefore demanding toleration, or rather as somehow wrong-but-reasonable and therefore demanding (reciprocal) recognition? Does the difference rest in the quality of the other’s views? (For example, does some definable range of reasonable use of evidence and moral consideration of others exist, such that views can either fall within or outside of that range?) Or does the difference rest in my own level of certainty about the view I hold? (I am presently persuaded by it, but I recognize that my reasons for holding it fall somewhere short of demonstrative certainty.) Or does the difference lie in the nature of the matter in question? (Some issues admit of clear, demonstrable truth or falsity; others are matters of indeterminate and inconclusive evidence; and still others are matters of mere taste.)

The important point here is how the question of disagreement on matters of metaphysical and ethical conviction fits into this scheme of toleration-versus-recognition. Some contemporary Western political philosophers believe themselves committed to a distinctive position on religion that is neither skeptical about truth-claims nor merely utilitarian or instrumental in its approach to social difference. They do not assume that the persistent attachment to religion is evidence of a failure of reason and then focus on how it might nonetheless support, sustain, or at least not interfere with this or that secular vision of political justice or emancipation. Rather, they justify self-restraint in politics (i.e., “We do not just articulate what we think is true or ideal for all persons and then seek its realization”) by referring to the way human reason and moral psychology tend not to converge on universally shared beliefs. The most famous articulation of this approach is, perhaps, that of James Madison in “Federalist No. 10”:

As long as the reason of man continues fallible, and he is at liberty to exercise it, different opinions will be formed. As long as the connection subsists between his reason and his self-love, his opinions and his passions will have a reciprocal influence on each other; and the former will be objects to which the latter will attach themselves.… The latent causes of faction are thus sown in the nature of man; and we see them everywhere brought into different degrees of activity, according to the different circumstances of civil society. A zeal for different opinions concerning religion, concerning government, and many other points, as well of speculation as of practice… have, in turn, divided mankind into parties, inflamed them with mutual animosity, and rendered them much more disposed to vex and oppress each other than to co-operate for their common good.