Think Progress reports:
During his controversial speech at New England prep school Choate Rosemary Hall yesterday, former Bush adviser Karl Rove was challenged by a student “to explain how giving gay people the right to marry would endanger other people.” Rove dodged answering her at first, saying that the issue “should be resolved by a legislature or a referendum, not a court.” But the student, Choate senior Marla Spivack, continued to press him:

Spivack kept pressing. “You never actually answered, how does it threaten anyone?” she asked.
Rove asked, what’s the compelling reason to throw out 5,000 years of understanding the institution of marriage as between a man and a woman?
What, Spivack countered, was the compelling reason for society to allow interracial relationships when they had once been outlawed.
Then Rove invoked the Declaration of Independence before Spivak interjected that its reference to “life, liberty and the pursuit of happiness” seemed to support her claims.
Eventually, Rove wiggled out of the debate by asking Spivack “when she planned to run for political office.”