“You know those opponents of marriage equality who said government approval of same-sex marriage might erode bans on polygamous and incestuous marriages?” asks the professor, Kent Greenfield. “They’re right.” “The left is in this bind in part because our arguments for expanding the marriage right to same-sex couples have been so compelling,” Greenfield brags proudly. “Marriage, we’ve said, is about defining one’s own family and consecrating a union based on love. We’ve voiced these arguments in constitutional terms, using claims arising from the doctrines of ‘fundamental rights’ and equal protection.”