Gay marriage and the usual suspects

Here are George Will’s thoughtful observations on the gay marriage controversy. Will’s discussion brings to mind some of the normal liberal fallacies that infect so many public policy debates. First, there’s the familiar notion that because an institution is working imperfectly, it is fair-game to be taken over and/or re-defined by a bureaucracy or, preferably, the judiciary. In the case of marriage, the fact that divorce rates are far too high is considered by some an argument that marriage should be redefined by judges, or at least that it can be without any real cost to the institution. This strikes me as similar to arguing that because the Everton soccer team is doing poorly this year, it should bring in rugby players, or perhaps simply switch to playing rugby.
Second, Will notes that neither side of the debate can prove what (as an empirical matter) the consequences of altering the public meaning of marriage by including same-sex unions would be. Some (not Will, as far as I can tell) argue that unless legislators can prove that rules reflecting the moral judgments of society are justified by empirical data, these rules should be overturned. But, except for certain philosophical pragmatists, morality-based rules are justified (or not) by non-empirical concerns. Thus, the absence of empirical data, if relevant at all, should hardly be dispositive. Even as a bit of a pragmatist myself, I recognize that refusing to recognize moral judgments as a substantial state interest that can justify public policy when challenged in court will tend to read moral concerns out of law and public policy (with bad pragmatic consequences).
Finally, of course, there are many public policy debates in which neither side can present compelling empirical evidence to support its position. Indeed, the more revolutionary the proposed policy change, the more difficult it will be to present meaningful empirical data. Why shouldn’t the burden of proof be on the side that wishes to redefine vital social arrangements and overturn society’s moral judgments?