Marriage season is now upon us, and in year 2012 there are stirrings. Perhaps not in heteronormative quarters, where divorce remains a spectator sport, but unfecund passion is blooming where moral fences and rocky laws abound. Just recently our president, commander-in-chief of the bully pulpit, revealed that he has evolved, no longer uncomfortable with what was once termed, with slight derision, gay marriage, but is now known as “marriage equality.”

Perhaps President Obama was pushed to catch up to his verbose Veep or perhaps he saw this revelation as a strategy to open the promiscuous wallets on Hollywood’s Walk of Fame, but he was historic, rhetorically. So much for Barack Hussein Obama as closet Muslim fundamentalist. True, he did not call on states to act on his pronouncement and certainly didn’t call on the Supreme Court to do so, but the occasion was remarkable partly because here as elsewhere Obama was leading from behind. But leading still.

When I teach classes on social movements, I attempt a dangerous feat. I ask students to imagine how not so very long ago – indeed, in my conscious remembrance, a half century back – American citizens could believe that segregation was right and proper. While many other citizens disagreed, the defenders of segregation in 1962 were not wild-eyed, in-bred, or illiterate. They were, some of them, responsible, highly educated, and often compassionate. Most were soon to decide that they were wrong, even if they did not phrase their racial conversion narrative in that way. But in the American South between 1964 and 1972, many former segregationists recognized that they were standing on the “wrong side” of history, or, as Leon Trotsky acidly phrased the matter, in the “dustbin” of history.

Perhaps we need be grateful that contemporary students have so much difficulty in figuring out how a plausible segregationist argument was possible. Today such a policy seems more than wrong; it seems inexplicable.

And perhaps we are at a branching point today – or soon – in that much the same will be said of our current marriage debate. Someday students may puzzle at the very core of the dispute. What was the other side exactly? But this represents the broad, although not immediate, direction of social change. In this President Obama’s change to embrace “gay marriage” does constitute an evolution in his thinking, whereas his previous decision while an Illinois politician to shift away from being supportive of marriage equality constitutes a dramatic flop-flip. When you shift alone with society you deserve credit, even if belated and incomplete. This generous judgment is true for segregationists, who should not be judged perfect, but only better.

Looking forward and not gazing back, there are issues to be resolved. Should this loving arrangement be given the label “marriage” or the lovingly bureaucratic “civil union?” If the latter is the official descriptor, I suspect that the label “marriage” will still become widespread in public discourse. And if marriage is a contractual relationship among citizens, what is the objection to multiple loving, consenting partners. While the social arrangements and legal entanglements are more fraught and complex as one moves from the world of dyads to triads and beyond, the moral justification is powerful, even if few will take advantage of such complexities.

As the supporters of marriage equality have emphasized, compelling claims against it are lacking. Except for one. This is the assertion of “custom and tradition.” Social arrangements are sticky things. However, it is precisely this argument that was used to support state-enforced racial separation. While one should not dismiss the stabilizing principle of custom and tradition – too much change too rapidly is disorienting – custom and tradition are not an argument, but only a mantra.

Ultimately supporters of marriage equality will triumph, but, if done right, it will take time for many citizens to get used to the idea. An immediate fiat is almost as dangerous as no change at all. One can plausibly argue that our forty-year scuffle over legal abortion has precisely this root. One day laws prohibiting abortion were in place and the next they had vanished, permitting no slow evolutionary slide. Those who argue that change can’t come soon enough are often as wrong as those who suggest that change must never arrive.

But change will arrive – it is arriving – in popular culture, in literature, in journalism, in education, and in politics. And some day, perhaps before I retire, students will struggle when I ask them to imagine a day in which marriage could not be between any loving people. Or at least between those who claimed love at the moment of justifying their relationship to the State.