It happened without a Summer of Love, without Timothy Leary, without a groovy anthem or a shaggy new national look. In the past decade or so, there’s been a silent revolution in American culture, one at least as profound as the ’60s upheavals.

We’ve hardly taken notice of it, because it happened in people’s minds instead of in the streets, happened in ordinary people instead of in the elites and the punditocracy.

We don’t want to judge others for anything, even if what they’re doing is destructive.

Compared to just a few years ago, we have a completely different set of ideas about what constitutes acceptable behavior. As Caitlyn Jenner puts it in her new reality show, “I’m the new normal.”

Consider America circa 2002: Not that different from today, seemingly. A time traveler who spent a few hours walking around your town then and now might have a difficult time filling a small notebook with observations about what’s changed. Maybe there are more Starbuckses. And what happened to Blockbuster Video?

Yet support for gay marriages to be treated the same as straight ones went from 39 percent just nine years ago to 60 percent today, according to Gallup. As recently as 2010, a clear majority opposed gay marriage. Today, a large majority support it.

As for the broader issue of whether gay and lesbian relationships are even morally acceptable, only 40 percent said yes in 2001. Today that number stands at 63 percent.

In other words, more Americans are OK with homosexuality than were OK with divorce (59 percent) in 2001. A decade ago, a plurality of Americans did not even believe that homosexuality is innate.

Today, by a margin of 51 percent to 30 percent, Americans think if you’re gay, you were born that way.

What caused all these changes? It’s hard to say. Older Americans are dying off. Popular culture not only deals with homosexuality approvingly, but has added more and more gay personalities to the mix.

In 2002, “The Ellen DeGeneres Show” had not yet debuted. As my colleague Sara Stewart noted, today she’s “our culture’s lovable gay grandma.”

Are we more attuned to pop culture than we used to be? Maybe. In the 1960s and 1970s, marijuana usage became a hugely popular theme in entertainment. Public opinion, though, did not follow.

In 1969, the year of “Easy Rider,” support for legal pot stood at 12 percent. As recently as 2003, it was still only 34 percent. But in the last two Gallup polls on the subject, in 2013 and 2014, support hit an outright majority for the first time.

And yet only 7 percent told Gallup in 2013 that they themselves currently take marijuana.

Americans are simply, broadly, more tolerant of others who are unlike them. As a general trend, that’s heartening. On the other hand, what comes along with this mass departure of moral judgment from public life?

Let’s say we grant that it’s morally acceptable to smoke weed. Is it morally acceptable, then, to spark up a joint every day at lunch? Sure, as long as you’re not endangering others. It’s still not terribly wise, though.

If your unemployed roommate drifts through life perpetually stoned, you may resist telling him what he’s doing is morally wrong, but it is, in some sense, not OK. Does being a good and tolerant citizen mean you should shrug when a person chooses to spend his life wasted?

Increasingly, we don’t want to judge others for anything, even if what they’re doing is destructive. But is being non-judgmental the same as granting tacit approval, even support?

Consider the amazing turnaround in people’s views of single parenthood. As of 2002, only 45 percent of Americans thought it was “morally acceptable” to have a child outside of wedlock. Today it’s 61 percent.

And yet, concurrent with that shift in opinion, it’s become obvious that whether or not it’s “morally” wrong to have a kid without being married, it’s undoubtedly bad for that kid.

To consider just one of many alarming statistics, if you’re a child growing up in what was once called a broken home, you’re six or seven times as likely to witness domestic violence as those brought up by married parents.

Perhaps it’s bad, judgmental, even morally wrong to mention that. For all of the disgust for moralizing, we have more micro-moralizing than ever.

Raising a child without a spouse is absolutely fine, but devise an awkwardly worded joke or muse about the comportment of the president’s daughters and you might find yourself denounced from coast to coast, even if you were not previously considered a public figure.

If you’re a baker, you can refuse to cater a gay wedding for any reason you please — you’re too busy, you’re taking a few days off, you’re hung over — but if you say the words, “I don’t approve of gay marriage,” you’ll not only be vilified, you’ll be bankrupted.

Let’s hope that, 15 years from now, another cultural revolution has followed — and Americans will be able to think whatever they want without fear of condemnation.