Other than a few Mitt Romney supporters, most of us view evolution as a wonderful biological mechanism to which we owe our supposed higher intelligence. So Obama's "evolution" from a foe to a supporter of same-sex marriage deserves tremendous praise. But before we go all ga-ga over the president, let's remember:
He didn't evolve on his own. In this case, the evolution needed a push, from generations of LGBT activists and supporters, who put the issue in front of the world, made it a basic matter of civil and human rights, and forced Obama to realize that he could no longer duck and had to take a stand.
Remember FRD's famous statement to activists? "Now you have to make me do it." That's what happened here. Obama made the political calculation, of course, and it's a good one -- energizing his base is more important than angering a bunch of people who weren't going to vote for him anyway. But there's more to it, and I think Paul Hogarth has the right line:
Biden’s statement may have been the final trigger, but the LGBT movement deserves the credit – despite the odds – to hold firm on getting the President to take this historic stance. And it’s a lesson that other progressive constituencies should take heart in, as we strive to make Barack Obama the President we hoped he would be.
Let's also remember that this really started in San Francisco , with an act of what I like to call civic disobedience. At the time, a lot of critics said that Mayor Gavin Newsom was hurting the Democratic Party by making a move before the rest of the nation was ready for it. But what he did eight years ago was force the rest of the nation to get ready for it -- and the subsequent legalization of gay unions in a growing number of states has shown America what the Boston Phoenix referred to as "the utter, mundane normality"  of same-sex marriage.
We all knew this moment was coming. The demographics can't be denied. Almost everyone younger than 30, and most people younger than 40, supports same-sex marriage. The country is changing -- in this case, in a very positive way -- and Obama was risking being on the wrong side of history. Even the Republicans seem to get that -- they're running away from this issue as fast as they can.
So now it's likely that L.A. Mayor Antonio Villaraigosa will have his way and the Democratic Party platform will have a same-sex marriage component. Romney will be on the defensive on a key social issue - a huge change from the past. The Supreme Court will be more likely to uphold Judge Vaughn Walker's decision on Prop. 8  (yes, the high court is political and changes with the norms of society, sometimes slowly, but the president's statement will have a clear impact.)
So this is huge -- not just because of the impact but because of what it says about the power of progressive movements. Now let's make the president raise taxes on the rich.