While I acknowledge that the practical considerations do complicate things for advocates of polygamy, I do not agree that they are sufficient to refute the existence of a slippery slope regarding this issue.

For starters, the slippery slope argument is not that Gay Marriage WILL lead to Polygamy, only that it COULD. More specifically, many (not all, obviously, but many) of the arguments against polygamy are the same arguments that are used against Gay Marriage, and if those arguments are refuted in the case of Gay Marriage, they are no longer valid at all.

In fact, the very post to which you link itself quotes one of these arguments:

“Group love (sometimes called polyamory) is already legal, and some people freely practice it. Polygamy asserts not a right to love several others but a right to marry them all. Because a marriage license is a state grant, polygamy is a matter of public policy, not just of personal preference.”

The same argument could be made regarding Same Sex Marriage, and in fact is: Gays can already love/have sex with/live with whomever they please, why do they need the State-Sanctioned “Marriage” title? Supporters of gay marriage raise some significant objections to this argument. I’ll neither agree or disagree with it at this point, I’m simply pointing out that it’s already been used and attacked in one example, and is this vulnerable in the other.

Secondly, the “Practicality” objection alone only stands if other objections still stand to some extent. If all other objections are overcome, the practicality issue will be viewed as nothing more than an obstructionist excuse — sure, it’ll make things complicated, but they’re already compicated with all the levels of divorce and remarriage and Domestic Unions and Living Wills and a myriad of other already existing social and legal contracts that we face as it is.

Because in the end, moral and civil rights considerations will trump practical considerations. And if same sex marriage advocates can frame their issue as one of Civil Rights, so can the polygamists — and in fact, that’s what they’re starting to do.