Libertarians support gay marriage because individuals should be free to have whatever consenting relations they want. Liberals support gay marriage because they want us all to officially respect gays as much as straights; gay activists have earned their group more respect.To which Gelman responds:
I think a more accurate statement would be, "Liberals support gay marriage because they don't think it's fair that straight people can marry and gays can't," or "Liberals support gay marriage because some gay people want to marry and they don't see why they shouldn't beAs I've written elsewhere, I think that whether one fundamentally holds to Thomas Malthus (there are too many people on the planet) or Julian Simon (people are the Ultimate Resource) colors one's views on abortion, embryonic stem cell research, and gay marriage. I offer Gelman these statements: "Liberals support polygamist marriage because they don't think it's fair that straight and gay people can marry and polygamists can't" and "Liberals support polygamy because some gay, bi, and straight people want to marry and don't see why they should be limited to groups of two." I think bisexuals may pioneer the legalization of polygamy, but the big beneficiaries will be "religious" zealots that want to "be fruitful and multiply."
The point that I'm making is that the liberal arguments for gay marriage would also be made for polygamy except that liberals tend to want fewer people—their views are colored by their Malthusian fundamentals.