But there's another way to look at Senator Obama's case that has affinity with a certain line of argument offered by those who defend what is called justificatory liberalism. Given the obvious limitations of a political speech, and given the senator's background in Constitutional Law and jurisprudence, I suspect that he holds to some form of justificatory liberalism. So let us imagine that Senator Obama is defending a version of this point of view, which would go something like this: because religious citizens have an evidential set-sources of authority, background beliefs and reasons-not shared by their neighbors, they should restrain from employing those sources as the basis for the reasons why they enact laws that limit the liberty of their fellow citizens who do not share those sources of authority.
But it's not clear why the religious citizen should accept this rule if she has fulfilled all her epistemic duties and believes that she has good grounds for the coercive laws she supports. Surely it is correct that each of us comes to the public conversation with a cluster of beliefs that we hold for a variety of reasons, many of which are based both on arguments we have carefully assessed, and authorities that we believe are reliable and have no reason to distrust. But in that case, the typical non-religious citizen enters the public square in precisely the same position as the typical religious one. And in both cases, each likely supports laws that she thinks are reasonable and necessary but that in some cases have the consequence of limiting the liberties of others, even though each is not likely to see that consequence has a net harm, since each will see it as an advancement of justice and the public good.
Consider the following example. In Massachusetts, soon after the state's Supreme Judicial Court in 2003 required that the state issue marriage licenses to same-sex couples, Catholic Charities, which was at the time in the child adoption business, was told by the state that it could no longer exclude same-sex couples as adoptive parents, even though the Catholic Church maintains that same-sex unions are deeply disordered and sinful. Because it did not want to compromise its moral theology, Catholic Charities ceased putting children up for adoption.From the perspective of the Catholic citizen who opposes same-sex marriage, this state of affairs limits her liberty and that of her Church based on sources of authority (e.g., arguments for same-sex marriage that its advocates find persuasive, a philosophical anthropology and view of human sexuality that same-sex marriage proponents find intuitively obvious, etc.) that she does not share with those who support same-sex marriage, including Massachusetts's Supreme Judicial Court.
On the other hand, the proponents of same-sex marriage, including many gay citizens, see this state of affairs as an advancement of justice and the common good. For that reason, they find same-sex marriage as an almost logical entailment of what they think the ends of liberal democracy should be. For, in their minds, the state is unjust if it denies its citizens the opportunity to marry whomever they choose based on an understanding of human sexuality inexorably tied to a source of authority that gay citizens reject. On the other hand, opponents of same-sex marriage see the injustice in the state's actions coercing them to embrace a policy that their sources of authority maintain is deleterious to social justice and the public good.
My point is this: if we interpret Senator Obama's position as suggesting that one cannot support a law that limits another's liberty if one's reason for the law is based on an authority not shared by one's fellow citizens, neither side in the same-sex marriage debate can escape the scope of that prohibition. One way to avoid this problem offered by some same-sex marriage advocates is to claim that liberal democracy by its very nature entails a particular view of the human person that requires that the government allow same-sex marriage. But this just begs the question, and also seems to violate justificatory liberalism; for it privileges, without argument, a controversial view of the human person over which reasonable citizens disagree against which they offer sophisticated and thoughtful arguments. And its plausibility depends on sources of authority that the opponents of same-sex marriage reject.Much of this article was incorporated in a revised fashion in my latest book, Politics for Christians: Statecraft as Soulcraft (InterVarsity Press, 2010)