If Republicans are fiscally conservative, why have they failed to make the one "valid" argument against gay marriage?

(Before proceeding, I should be very clear that by "valid" I don't mean that the argument is satisfactory or convincing. I merely mean that it doesn't rely on fallacious reasoning, abject falsehoods, or imagined costs or risks; i.e. I am defining "valid" as meaning an argument which identifies a real cost or risk, no matter how trivial that cost may be when compared to the benefits of doing the right thing.)

One thing I am fond of saying to explain my rabid support of gay marriage is that, unlike the vast majority of political issues, this one is a no-brainer. I have previously claimed that legalizing gay marriage is a rare legislative action that is all benefit and no cost. This differs from other issues on which I have a strong opinion, but where I acknowledge there are significant costs to the position I advocate, making it an issue where reasonable people might differ (e.g. my opinions on abortion rights and the death penalty fit this profile¹). We don't even have to figure out the logistics of enacting the legislation -- you just say, "Now all marriage laws are exactly the same as they were yesterday, except the gender of the involved parties doesn't matter." Done.²

So I was contemplating that this morning, and I suddenly thought of an actual, real cost of legalizing gay marriage. Mind you, it's a rather small cost, and even if it were a large cost I would still strongly support gay marriage because it's simply the right thing to do. Denying full civil rights to the LGBT community cannot be deemed acceptable under any circumstances.

Still, since the cost I have identified has a direct effect on the federal budget, it seems odd that a political party that nominally prides itself on fiscal responsibility has so far failed to raise this argument in their attack on gay marriage. (Or, it would seem odd if I actually believed the modern Republican party had any clearly articulated ideals at all, other than providing a haven for bigotry and promoting unapologetic demagoguery)

Without further ado, here it goes:

I'm not exactly sure how the numbers work out, but it seems likely that recognizing gay marriage at the federal level would create a sudden spike in the number of "Married filing jointly" tax returns, with a presumably negative effect on tax revenue. I don't imagine the impact will be large, and as I said, even if it were, it would be irrelevant in a discussion on civil rights. And furthermore, this can't become a reality until DOMA is either repealed or correctly ruled unconstitutional under the 14th Amendment, so the only way it can be applied to legalization of gay marriage at the state level is via the "slippery slope" argument (but we know gay marriage opponents have no qualms about using that usually-fallacious argument...)

But isn't it strange that this argument hasn't been made? Doesn't it seem like a perfect fit for Rush Limbaugh to be blathering on about how "these deficit-happy liberals want to deal a further blow to the federal budget right in the middle of the worst recession in recent memory?"

Could it be that it is beneath even the modern GOP to argue that civil rights should be arbitrarily denied to a certain group in order to increase tax revenue? It doesn't seem like it... The only answer -- and I guess we knew this already, but it is just further evidence -- is that when the GOP has a choice between promoting fiscal conservatism vs. promoting bigotry, they're going to go with the one that they know their audience can grasp.

¹My position on those two issues, and why it's not as cut and dry as gay marriage...

On abortion rights: I support full abortion rights with no restrictions on when they are performed or on medical necessity. I recognize that this position would conceivably allow a small number of abortions to occur which reasonable people -- myself included -- might view as hugely immoral, on par with infanticide. I think this cost/risk is justified because a) the vast majority of women seeking a late abortion are doing so for legitimate medical reasons, b) both the government and insurance companies have shown themselves to be completely untrustworthy at discerning what "legitimate medical reasons" are in regards to abortion, and c) good luck finding a doctor willing to perform a 3rd-trimester abortion on a healthy fetus inside a healthy mother, anyway.

We might imagine a distant future when reproductive rights are not so politicized, when regulations might be put in place on late abortions to define parameters when they are acceptable -- but in the near term any attempt to do so is simply going to be used as a foot in the door to deny appropriate medical care to women undergoing one of the most devastating events of their lives. Still, there are real costs here, and (unlike gay marriage) the issue is a bit tricky.

On the death penalty: It's a waste of money, a waste of time, and far too often a waste of an innocent life. But it is still less of a no-brainer than the gay marriage issue, because while the death penalty is a lousy deterrent for violent crimes, there is some suggestive evidence that a person who does not believe proper "justice" is being done in response to wrongdoing is less likely to behave ethically. We might extend that to a whole population, and argue that by failing to execute violent criminals, we contribute to a general nonchalance about unethical behavior.

Okay, that's a stretch. But the other reason I don't feel quite as passionate about the death penalty as I do about gay marriage is that for criminals whose actions are beyond reprehensible and whose guilt is not in doubt, my reaction to their execution is pretty much a big shrug. The recent execution of the DC sniper comes to mind. I don't generally support government-sponsored murder, and I feel like it's wasteful from a practical perspective -- but do I feel a sense of outrage that this guy was executed? Nope, not at all.

Don't get me wrong, on both of these issues, I still feel strongly. But there are major costs and benefits on both sides, so it requires careful thought to come to a conclusion, and opinions could conceivably change over time. With gay marriage, there are simply no (non-trivial) costs to speak of, and I cannot imagine my opinion changing under any circumstances. Nearly unique among political issues, it is a complete and total no-brainer.

²Seriously, legalizing gay marriage is that simple. As we have seen by precedent in areas where it has been legalized, it's not even a big deal if the existing marriage license forms say "Husband" and "Wife". People just cross out the erroneous appellation and replace it with an appropriate one for the time-being, until the local government can get around to printing out "Spouse/Spouse" forms to correct that embarrassment. It's not ideal, but it shouldn't be a barrier to legalizing gay marriage, particularly in cash-strapped locales where expediency might dictate that the old-style forms remain in use until they would have needed to print new ones anyway.

Fixing those little remaining artifacts of prejudice like "Husband/Wife" forms is something that needs to be done, but it is not at all a requirement for legalizing gay marriage. Gay marriage could be legalized across the entire country, today, with nary a hiccup in the bureaucratic administration of marriage laws.