Argument: Marriage has always evolved; should now include gays
Andrew Sullivan. "Why 'civil union' isn't marriage." The New Republic. May 8, 2000: "The most common liberal argument for civil union but against marriage was summed up by First Lady Hillary Rodham Clinton in January. 'Marriage,' she said, when pressed to take a position, 'has got historic, religious, and moral content that goes back to the beginning of time, and I think a marriage is as a marriage has always been: between a man and a woman.' This statement, which is more elaborate than anything said by Vice President Al Gore or Texas Governor George W. Bush on the topic, is worth examining. It has two aspects. The first is an appeal to the moral, historical, and religious content of an institution unchanged since 'the beginning of time.' But even a cursory historical review reveals this to be fragile. The institution of civil marriage, like most human institutions, has undergone vast changes over the last two millennia. If marriage were the same today as it has been for 2,000 years, it would be possible to marry a twelve-year-old you had never met, to own a wife as property and dispose of her at will, or to imprison a person who married someone of a different race. And it would be impossible to get a divorce. One might equally say that New York's senators are men and have always been men. Does that mean a woman should never be a senator from New York?"
Steve Swayne. "The Case for Federal Civil Unions." Independent Gay Forum. February 28, 2004: "Americans, gay and straight, have been redefining marriage for years, and no constitutional amendment can stop them."