Ross Douthat in the New York Times has a useful piece on exactly why same-sex marriage damages the institution of marriage.

His piece is a response to the argument that says that same-sex marriage will have no impact on the health of the institution.

There are those who argue, Douthat points out, that same-sex marriage, far from damaging marriage, will actually strengthen the institution.

Quoting one of these writers, Jonathan Rauch, Douthat writes that same-sex relationships might “move toward both durability and exclusivity”.

According to Rauch, the example of gay couples taking vows would “strengthen marriage’s status as the gold standard for committed relationships”.

Douthat, however, posits another, perhaps more plausible scenario: “This vision embraces the institution of marriage, rather than seeking to overthrow it. But it also hints that the example of same-sex unions might partially transform marriage from within, creating greater institutional flexibility — particularly sexual flexibility — for straight and gay spouses alike.

Douthat says that gay writer and sex columnist Dan Savage is the leading advocate of this idea. Savage apparantly thinks marriage “is weighed down by unrealistic cultural expectations about monogamy”.

According to Douthat, Savage’s memoir about wedding his longtime boyfriend describes the way his own union has successfully made room for occasional infidelity.

“Far from undermining the stable home we’ve built for our child,” Savage writes, “the controlled way in which we manage our desire for outside sexual contact has made our home more stable.”

However, as Douthat points out, the results of this kind of experiment within heterosexual marriage are already in, and they don’t make for pretty reading.

Serial infidelity destroys marriage, it turns out, with disastrous results, especially for children. On the other hand, Dan Savage would probably argue that opposite-sex couples need to emulate many same-sex couples by putting more stress on emotional fidelity than on sexual monogamy, and of course if that road is followed, then marriage will have changed more radically than it even has to date.