Congratulations to gays and the marriage equality movement for a major victory in New York. But rather than marching along in a pride parade, I need to be contrarian and point out one small but significant area in which the opponents of gay marriage actually have a point. It's not a decisive point by any means -- I still favor allowing gays to marry and so should you -- but it nags at me.
The pro-gay-marriage position is based on the idea of individual and equal rights, and a standard argument for it is that allowing gays to marriage cannot have any conceivable impact on heterosexual marriages (eg here or here). This seems very wrong to me. Despite this argument generally coming from the left, its underpinnings are identical to the libertarian/conservative dismissal of social reality, put in its starkest form by Margaret Thatcher's line "there is no society; there are only individuals". Well, no. Society is a real thing, we are all involved in it in one way or another, and it is involved with our lives. Marriage is a social institution, not merely something two individuals decide of their own free and independent wills to do. This is true of pretty much everything, but it's glaringly obvious in the case of marriage, which comes with a huge set of legal, social, and cultural baggage.
So extending the bounds of marriage to include same-sex couples is in fact a big change that impacts everyone, whether or not they themselves are going to get hitched to someone with similar genes and plumbing. Conservatives are right to sense this. Society works by means of norms and institutions, which are very real things (and sorry if I sound like a college freshman who has been bowled over by his Soc 101 course, but my naive and amateurish interest in the sociological won't be still) and changing them changes the world for everyone.
Now, that particular bit of truth is quite separate from the idea that such a change is necessarily pernicious. And even if it was, those theoretical harms would have to be balanced with the very real harms done to individuals by denying them equal rights.
But proponents of marriage equality should be careful in their arguments. Extending individual freedom is great, but pretending that it doesn't have any impact on society is a bad tactic because it isn't true, and people (including the people who need to be convinced in order to continue the legislative victories) know that it isn't true.
The issue is complicated by the fact that marriage generally has a religious and a secular component, but they are tightly interwoven. Proposals to split it up and get government out of the marriage business entirely and just have it manage the legal relationship of civil union made a lot of sense, but that's not the way things have been playing out. Marriage has remained a unified concept and that's where the battle is taking place, and if our side wins let's not pretend that there was a ground to fight over and the other side has not lost something.
The larger issue is that the left should not be in the business of making libertarian arguments and ceding the ground of society to conservatives.