Nelson Lund has an op-ed on Perry v. Schwarzenegger (the case in which Judge Walker held that California’s Proposition 8 – permitting only heterosexual couples to marry – lacks a rational basis). It exposes a tension in the (mainstream) public rationales for and against gay marriage.
Lund gives an apt statement of the conservative position’s most recent iteration.
(C1) Those who say that there is no rational basis for forbidding homosexual couples from marrying thereby assert that those – voters and politicians – who favor this policy are irrational or driven by animus (or “moral or religious contempt for homosexuals and their relationships,” in Lund’s phrase). But this is absurd and distasteful.
(C2) Further, there is a rational basis for preserving the traditional forms of marriage, viz. that extending marriage to homosexual couples might well make marriage less effective at serving its main public purpose: “to encourage biological parents, especially fathers, to take responsibility for their children.”
The (mainstream) liberal response to these hypotheses is:
(L1) The fact that a policy is irrational (or only rationalizable in terms of animus) doesn’t mean that supporting such a policy is irrational (or only rationalizable in terms of animus). One can support the policy because one accepts the (false) justifications for it that, if they were true, would supply a rational basis. Alternatively, one can support it because – a perfectly rational thing – one’s favorite authority (be it public intellectual or political party) supports it as well. In short, judging a policy irrational does not amount to judging its supporters irrational, because it doesn’t amount to judging its supporters at all.
(L2) There is no rational basis for preserving the traditional forms of marriage, because only on the most outlandish scenarios would permitting homosexual couples to marry thwart marriage’s main public purpose. (Divorce, on the other hand… but its legitimacy is not in question.)
The problem for conservatives is that the most likely scenario on which extending marriage to homosexuals prevents marriage from serving its main public purpose is if doing so causes it to lose its sacrosanct luster in the eyes of many heterosexuals. But this would only happen if there is widespread moral and religious contempt for homosexuals and their relationships. Thus, (C2) implies the (real possibility of the) “absurd and distasteful” result that (C1) mentions. Which means – no doubt unbeknownst to them – that it is the liberals who respect the good sense of the American people on this question.
Of course, this last point is more snark than truth, because liberals also have a problem. If all legitimate rationales for preserving traditional marriage are outlandish, then those who promote that policy are either idiots, or invoke the legitimate rationales as a pretext. (L2), then, pushes us to deny (L1).
Update: Though it might read otherwise, this is more than just indulgent pap. I think it points to a real problem with rational basis analysis – at least in the present ideological climate – which is that there is no non-politicized account of what qualifies as rational. Liberals presuppose that conservative rationales for restricting traditional marriage are merely pretextual. This presupposition is essential to their denial that the nightmare scenarios that conserving traditional marriage is supposed to avert are too outlandish to count as a legitimate worries (despite the fact that intelligent conservatives do not discount them).
Conservatives, likewise, assume that when liberals deny that there’s a rational basis for preserving traditional marriage they are motivated not by their epistemological commitments, but by their moral sentiments.
When each side judges the other’s evaluation of reasonableness to be merely pretextual, it is a sign that rational is (for ideological reasons) an essentially contested concept. The rule of law breaks down wherever essentially contested concepts exist. The breakdown ramifies if the essentially contested concept has wide application, as does the rational basis test.