There’s a popular (I’m tempted to say “standard”) secular liberal argument in support of a secular public sphere. Appeals to faith, the argument goes, might have purchase on the faithful, but not on those outside a particular sect. The Bible interpretation of a certain denomination or the pronouncements of popes and rebbes may legitimately persuade or motivate those who accept such authorities. But we live in a pluralistic society where no single overarching view of the good life is dominant. In politics, we often decide on public policies that will affect everyone. In such cases, anyone who wants to make headway beyond their sect will have to produce public reasons that are available to everyone. Public reason—including our notions of relevant evidence and the reasoning process itself—has to be secular by its very nature.
We might challenge such a view of public reason on grounds of ethnocentricity: it seems to be rooted in a Protestant religious environment. Many Muslims, for example, might be suspicious of it, since they often conceive of public reason in at least monotheistic terms. Acknowledgment of the authority of God, it seems, is a prerequisite for reason to have effect in the public realm. This is the basis of trust, of people having the sort of character that make them trustworthy public actors. But even then, the secular liberal ideal might retain its appeal. After all, pluralism is a fact of life in many Muslim countries as well. There too, political proposals regularly have to persuade sects who interpret the Quran differently or who put trust in different structures of religious leadership. Unless Muslims want the sort of coercion endured by Saudis and Iranians, they need to appeal to a sort of public reason stripped at least of its most sectarian appeals to faith-based authority.
All well and good: presumably “use reasons that have a chance of a broad appeal” is good advice for participants in politics. But I think the secular nature of public reason is oversold. Most modern political actors already take that advice, and it does not seem to make much of a difference.
Consider the conservative Christians who make Americans liberals lose a lot of sleep. They are happy to provide public, ostensibly secular reasons for their positions. If they object to evolution in public education, they are ready with an extensive creationist literature that rarely appeals to faith. Even if they thump the Bible, they have extensive apologetic efforts to convince nonbelievers that, based on secular reasoning, the Bible is The Best Book Ever.
Their reasons look like very bad reasons to those who are secular or who have the relevant expertise. But bad reasons can still be public reasons. We would drift far out of the liberal political tradition if we were to insist that only good reasons should enter public argument, or that it somehow does not count when substantial numbers of citizens are persuaded that bad reasoning is good. Who, after all, decides on the worth of an argument? The relevant set of experts? Perhaps—where examples such as evolution or global warming are concerned, the tendency of conservative Christians toward denialism really is scary. But then again, liberal academic expertise can also go off the rails. The most consequential examples of pseudoscience I can think of come not from creationist circles but mainstream economics. And that is strictly a secular liberal affair.
But that would be strange advice. Would then a secular liberal keep anthropogenic global warming out of political discussion, since it clearly will never be accepted by Americans of a hypercapitalist quasi-religious persuasion? Will we leave evolution out of the public schools, since public debate about it is a stalemate?
So we are left with public reason in a different sense. We reason to reach the undecided who might still be persuadable, in order to build up a coalition in support of a policy. We reason as part of a process of negotiation with even those we cannot hope to persuade, but with whom we must live together. But then, there is very little special about such a thin notion of “public reason.” Anyone involved in any politics reaching beyond the narrowest sect, however unsecular and illiberal they may be, relies on reasoning in that sense. We don’t get much closer to a secular polity that way.
Therefore, my inclination is to back off of the “public reason” argument for secularism. We need to find ways to argue for secularism as a substantive political position, as part of family of particular visions of the good, rather than trying to smuggle secularity in through the back door, as a “neutral” procedural matter. When I don’t want supernatural beliefs influencing politics, this is because I think that in many cases they are false in ways that make believers impede my interests. It is not because I set aside faith as a domain untouchable by public debate, but because I see certain varieties of faith as nuisance. And if other secularists think the same way, we have some basis to collectively act on that.