Two more response are now available to Professor Robert George's argument that there is no objection to polygamy "as a matter of principle" once gay marriage is accepted. Philosophy professor John Corvino writes:

The issue is whether being a gay-rights advocate inherently "entails abandoning any principled basis for understanding marriage as the union of two and only two persons," as George puts it. And the answer to that question is obviously "no." [Jonathan] Rauch is a clear counterexample: he's a gay-rights advocate who adduces general moral principles to oppose polygamy.

Why does George claim otherwise? The answer has to do with his confusion about what it means to have a "principled" objection to something. More specifically, he confuses having "a principled objection" with having "an objection in principle." The difference is subtle but important. To have a principled objection is to base one's opposition on principles (rather than simply to assert it arbitrarily). Rauch surely does this.

By contrast, to have an "objection in principle" is to object to a thing in itself, not on the basis of any extrinsic reason. Rauch doesn't object to polygamy "in principle"; he objects to it for being harmful, and if it weren't harmful he presumably wouldn't object to it.

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This distinction is important, because once one moves from "no objection in principle" to "no principled objection," it's a short slide to "no serious objection"—and thus a bad misrepresentation of the position of mainstream gay-rights advocates.

So, to be clear: Rauch, Carpenter, Varnell, and others have a principled objection to polygamy, but not an objection in principle. But here's the kicker: neither does George. For George's natural-law position is based on the requirement that sex be "of the procreative kind." And polygamy is very much of the procreative kind. Even if one accepts George's nebulous "two-in-one-flesh union" requirement—which somehow allows [] sterile heterosexual couples to have sex but prohibits homosexual couples from doing so—nothing in that requirement precludes multiple iterations (and thus polygamy). If George wants to argue that polygamy is wrong, he's going to have to appeal to the same sort of extrinsic principles that Rauch invokes. Either that, or he's going to have to just baldly assert that marriage is two-person, period. If such ad hoc assertions don't count as abandoning "principled" argument, I'm not sure what does.

Paul Varnell also disputes George:

In a co-authored article with one Gerard Bradley, George states that male-female marriage has an "intrinsic value" that "cannot, strictly speaking, be demonstrated" and that "if the intrinsic value of (opposite sex) marriage ... is to be affirmed it has to be grasped in noninferential acts of understanding."

That is about as close to acknowledging defeat as you can get without explicitly saying so. What if George Wallace had said that the superiority of the white race could not be demonstrated but could be "grasped in noninferential acts of understanding"? Certainly there was a sizable constituency for just such a view, but undemonstrable "noninferential acts of understanding" are a poor basis for creating public policy in a secular civil society.

Then too, Robert George and his colleagues have never explained very well what it is about their own requirement of a male-female polarity for marriage that excludes polygamy. It is hard not to suspect that George keeps harping on polygamy as an imagined consequence of same-sex marriage to distract attention from the far more obvious opening to polygamy his own principle entails.