BEFORE there was a national debate about same-sex marriage, there was a debate within the gay community about whether it was a worthwhile goal to chase at all.

This debate was tactical (since the cause once seemed quixotic) but also philosophical.

One current of thought saw the institution of marriage as inherently oppressive, patriarchal or heteronormative, better rejected or radically transformed than simply joined.

This liberationist perspective endured in academia, but mostly lost the political argument. Gay couples wanted the chance for normalcy, straight Americans were surprisingly receptive, and so a conservative case for same-sex marriage — the argument that marriage is essential to human equality and dignity — is flourishing.

And now that case rings from every paragraph of Anthony Kennedy’s marriage ruling, from the first lines to the “no union is more profound than marriage” peroration.

But in one of the ironies in which the arc of history specializes, while the conservative case for same-sex marriage triumphed in politics, the liberationist case against marriage’s centrality to human flourishing was winning in the wider culture.

You would not know this from Kennedy’s opinion, which is relentlessly upbeat about how “new insights have strengthened, not weakened” marriage, bringing “new dimensions of freedom” to society.

But the central “new dimension of freedom” being claimed by straight America is a freedom from marriage — from the institution as traditionally understood, and from wedlock and family, period.

The traditional understanding, which rested on sex difference, procreation, and real permanence, went into crisis in the 1960s and 1970s. But in the 1990s, when The Atlantic informed readers that “Dan Quayle Was Right” about unwed motherhood and today’s Democratic front-runner fretted about the costs of no-fault divorce, there were reasons to think that a kind of neo-traditionalism might still have purchase in America.

Not so today. Since the ‘90s, approval of divorce, premarital sex, and out-of-wedlock childbearing have climbed steadily, and the belief that children are “very important” to marriage has collapsed. Kennedy’s ruling argues that the right to marry is essential, in part, because the institution “safeguards children and families.” But the changing cultural attitudes that justify his jurisprudence increasingly treat this safeguard as inessential, a potentially nice but hardly necessary thing.

And the same is true of marriage itself. America is not quite so “advanced” as certain European societies, but our marriage rate is at historic lows, with the millennial generation, the vanguard of support for same-sex marriage, leading the retreat. Millennials may agree with Kennedy’s ruling, but they’re making his view of marriage as “a keystone of the nation’s social order” look antique. In their views and (lack of) vows, they’re taking a more relaxed perspective, in which wedlock is malleable and optional, one way among many to love, live, rear kids — or not.

In this sense, the gay rights movement has won twice over. Its conservative wing won the right to normalcy for gay couples, while rapid cultural change has made the definition of normalcy less binding than the gay left once feared.

In vain social conservatives have argued that this combination isn’t a coincidence, that support for same-sex marriage and the decline of straight marital norms exist in a kind of feedback loop, that an idea can have conservative consequences for one community and revolutionary implications overall.

This argument was ruled out, irrationally, as irrational, but it probably wouldn’t have mattered if the courts were willing to consider it. Too many Americans clearly just like the more relaxed view of marriage’s importance, and the fact that this relaxation makes room for our gay friends and neighbors is only part of its appeal. Straight America has its own reasons for seeking liberation from the old rules, its own hopes of joy and happiness to chase.

Unfortunately I see little evidence that people are actually happier in the emerging dispensation, or that their children are better off, or that the cause of social justice is well-served, or that declining marriage rates and thinning family trees (plus legal pressure on religious communities that are exceptions to this rule) promise anything save greater loneliness for the majority, and stagnation overall.

The case for same-sex marriage has been pressed in the name of the Future. But the vision of marriage and family that made its victory possible is deeply present-oriented, rejecting not only lessons of a long human past but also many of the moral claims that inspire adults to privilege the interests of their children, or indeed to bring children into existence at all.

Perhaps, with same-sex marriage an accomplished fact, there will be cultural space to consider these lessons and claims anew. Perhaps.

But seeing little such space, and little recognition that anything might have been lost along the road we’ve taken to this ruling, in the name of the past and the future I respectfully dissent.