Whatever the outcome of this week's historic Supreme Court hearings on same-sex marriage, one thing has become crystal clear: there is no longer, if there ever was, a rational argument to ban it. That very question -- when did it become unacceptable to ban gay marriage -- was at the center of a tense exchange between Justice Scalia and Ted Olson, the lawyer challenging Prop 8. "When did it become unconstitutional to exclude homosexual couples from marriage?" Scalia wanted to know, clearly believing the answer was "never." While the focus of Scalia's question was the constitutional grounds for banning gay marriage, his challenge applies more broadly as well: When did it became socially unacceptable to oppose gay marriage? Are there any grounds for holding that position beyond simple prejudice? Is it possible to oppose gay marriage and not be anti-gay?