From the department of pointless but compulsory exercises: every single time Rick Santorum or anyone with similar views says the following two things:
a) What, you want gay marriage? What’s next, legitimating polygamy?
b) The only form of legal, sanctioned marriage that any human society in all of human history has ever sanctioned is between one man, one woman,
the following rejoinder should be automatic from anyone in the audience to whom these things are being said:
c) Actually, Rick, the most commonly sanctioned or legalized form of marriage in human history across a wide span of societies has been polygamy, albeit with numerous variants. You might notice this if you actually read the Bible like you claim to.
However, there’s something more at stake in this special cultural conservative version of an all-Cretans-are-liars paradox. It’s not just a question of whether it’s ignorance or cynicism lurking behind political pandering.
What this paired sentiment expresses more deeply is have-cake-and-eat-it-too vision of modernity and progress among cultural conservatives, and not just in the United States. I see something of the same in the most skilled recyclers of the tradition-modernity relation that was given its undead power under colonial rule in 20th Century African societies.
If I were able to actually have a conversation with Santorum in which the historical reality of sanctioned polygamy in most human societies was made impossible for him to ignore or soundbite into oblivion, I’m willing to bet that the likely way out of the trap would be to argue that contemporary life has overcome that old evil, that we’ve progressed. Santorum and other American Christian conservatives would likely put the origin of that progress somewhere other than secular liberals would. They’d probably ascribe it to the rise of Christianity, all the way back to the early Church, whereas a more secular (or at least not religiously conservative) view would probably be than contemporary companionate, monogamous marriage (or any companionate, monogamous relationship, really) is a direct consequence of the working out of liberal individualism and rights-based personhood after 1750.
But it really doesn’t matter which claim you turn to. If you think that the relative eclipse of polygamy (still practiced and legally as well as morally sanctioned in many parts of the world) is a good thing, as I presume Santorum does given his suggestion that legally sanctioning gay marriage would open the door to polygamy, you believe in progress, that some aspects of the human condition have improved over time through the deliberate efforts of human beings to reform or change their social structures. And the moment you believe in that, saying, “It’s natural for people to live a certain way, all societies have done it that way” is off the table as a justification of contemporary policy whether or not your claim about the naturalness of living that way is true or not.
(Which, in fact, Santorum’s claim about the universality of nuclear families and monogamous marriages is not. Not in any way, including its address to homosexual practices. The foundation stone of ‘the Western tradition’, classical Greece, very much included sanctioned homosexual relationships between male citizens, for example.)
The moment you accept that progress is the real explanation for a transformation in human practices that you defend or endorse, you shouldn’t be able to invoke the universal, unchanging natural character of that practice against some other argument for yet another change or reform.
And yet, of course, this is done all the time, because the rhetorical alternatives are to either embrace arbitrary bigotry or construct some weird Tower-of-Babel claim about the future consequences of reform. E.g., in the case of gay marriage, if modern companionate relationships are a good example of progress, that means that we’re capable of changing how we legally and socially sanction and regulate marriage or relationships for the better. If we’re capable of that, why not include sanctioning companionate relationships between same-sex couples? With the invocation of unchanging, natural traditions disallowed, the only ‘why nots’ left are: because we should hate or despise same-sex couples for fundamentally arbitrary or non-rational reasons; or because sanctioning same-sex relationships would lead to further bad consequences. American cultural conservatives often take a stab at the second argument in public discourse (indeed, that’s where Santorum leads into his ‘oh noes bestiality-will-be-legal’ line) but this is an even easier set of arguments to puncture: either the imagined consequences are those which already follow in full measure from legally sanctioned heterosexual relations or they involve a vision that legal sanction is the same as contagion, that it creates practices that would not otherwise exist, a belief that has a lot of odd collateral implications.