From this perspective, the gay rights revolution reflects not only expanding notions of justice and equality but also long decades in which the economy, with its “spirit of perpetual innovation,” as Bell called it, conditioned Americans to expect that traditional limitations, of all kinds, could, and should, be overcome.

To be sure, traditionalism retains a powerful residual hold on the American mind, and even staged a comeback of sorts after the turbulent 1960s, the period that prompted Bell’s reflections. In 2004, “moral values” were voters’ top priority, according to exit polls. Not coincidentally, both anti-gay-marriage state ballot questions and Republican President George W. Bush prevailed.

In hindsight, though, that was a high-water mark. Last year, the CNN/ORC poll found that 55 percent of Americans say government should “not favor any set of values,” while only 41 percent want it to “promote traditional values.” The numbers were exactly the reverse 10 years earlier.