From the pro Prop 8 amicus brief:
"That same-sex relationships are not recognized as marriages does not reflect a public judgment that individuals in such relationships are 'inferior' or 'of lesser worth as a class', but simply the fact that such relationships do not implicate society's interest in responsible procreation in the same way that opposite-sex relationships do."
It's a worthy goal-- this "responsible procreation"-- but is that the only or main reason marriage was created? Pretty sure it had something to do with women being treated as property too. Regardless, thanks to our pro-survival biology it's always been pretty easy to procreate without marriage, so giving people an extra legal contract and tax benefits is only going to encourage the responsible pro-creators further, rather than do anything to keep the irresponsible in line, (at least nowadays with less social stigma, etc). I really don't see how giving some more people the legal status of marriage affects anyone's perception of the underlying responsibility or the value of the institution and its benefits. Also-- offering marriage to straight couples and excluding it from gay couples as your main solution to promoting responsible procreation would appear to be working less and less well (see rising divorce rates and out of wedlock birthrates).
The real question is: gay people exist, being gay is no longer illegal, and some gay people naturally want to participate in society including forming long term partnerships and families. They can either do that without any protections or encouragements to be responsible in the families they form, or they can do it within marriage or some sort of contract. Why hasn't this ever been suggested before? Because gay people were demonized or closeted throughout most of human history. In today's context, it makes perfect sense, for the same reasons the brief implies (promoting responsible child rearing and family structure, not just responsible sex!) to extend marriage and all associated benefits to gays. And since gays planning to raise kids together have to be generally very organized about making it happen, they're likely to be some of the most responsible participants in marriage. (Sure there will be some 24-hour-long drunken Vegas marriages in either case, but that's not at issue here. Ooh, side note-- can we also legislate a sobriety check when people fill out marriage licenses? That's a socially conservative effort I can get behind, I'm going to start a petition..)
So, let's extend marriage to gay people to preserve and extend traditional values. Let's keep and make marriage more of an "if you want to make a lifelong commitment and build a family" thing, rather than an "if you're a man in a tux and woman in a white dress, and you could accidentally have a kid together" thing. And if you want to do something further than that to encourage responsible procreation, let's focus more on straight people (hint: they're the ones making the babies accidentally) and have a look at all the other parts of our social and biological nature. Believe me, the gays are not the problem with straight relationships, and excluding them from marriage is not the solution.
-Stephen
P.S. As part of a modern day amicus brief for the Supreme Court of course you're not going to argue on the basis of how "inferior" or "of lesser worth as a class" any group of people are. But if you're arguing to leave this to voters, politics, and majority opinion-- that may be in essence what you are doing. In certain areas a majority of voters will certainly be voting based on their beliefs that gay relationships are inferior, as it was with racial animus in interracial marriage. So it's a complex issue of both popular opinion and of the moral imperative to uphold minority rights-- clearly the reason we can address it as minority rights is because popular opinion has swayed to the point where it is a plausible social concern. The oppression of a minority class is a worthwhile, but not the only, lens to view this issue through.
