Today's Washington Post cover story on the proposed gay marriage amendments in Virginia and Maryland quotes VA Del. John A. Cosgrove (R-Chesapeake):
The family is the foundation of our society, and it's been based on a union of a man and a woman since the inception of marriage.
That is, of course, ludicrously false: Since "the inception of marriage," polygyny has been a good deal more common than the "union of a man and a woman." Of course, the family structures of many of those societies were unattractive in various ways, but to even get to that point would be to admit the possibility of one of those thorny "arguments on the merits." Appeals to tradition, even false ones, are so much more pleasantly uncomplicated.