The California Supreme Court says gay marriage is a constitutional right. What a gift to Republicans!

You're kidding, right? Republicans are all talk. Conservatives should quit lying to themselves about the culture war. It's over. We've lost.

How? Polls show that most Americans are against gay marriage.

Yes, but not young voters. There's a clearly emerging social consensus in favor of gay marriage.

Maybe conservatives need better arguments.

Good luck with that. What we're arguing against is not gay marriage, really. It's modernity itself.

Oh, come on. Fifteen years ago, nobody took gay marriage seriously. Now you have courts declaring it a constitutional right.

True, but same-sex marriage doesn't come out of nowhere. It is the logical result of philosophical assumptions about the nature of truth that nearly everybody in the modern era takes for granted.

Huh?

A culture's ideas about truth determine most everything about its way of life. Eminent Harvard sociologist Pitirim Sorokin identified three general types of cultures, based on their fundamental orientation toward truth.

The ideational culture believes that truth is objective, known through religious revelation. The sensate culture holds truth to be subjective, perceived through the senses. The idealistic culture is a hybrid of the two, synthesizing the truth of faith with the truth of empirical observation.

What do ten-dollar words have to do with same-sex marriage?

Hold on, we're getting there. When the sensate civilization of pagan Rome collapsed, an ideational culture informed by Christianity emerged. All that mattered in the early Middle Ages was God. This eventually gave way to the idealistic culture of the 13th and 14th centuries, pioneered in part by Scholastic theologians like Thomas Aquinas.

Why didn't it last?

An intellectual debate ensued between Scholasticism and a philosophical approach called nominalism. Nominalists argued that we can only truly know what we can perceive through our senses; the rest is up for debate. Nominalism won. And that was the beginning of the modern world.

How?

Because that was the point at which Western civilization gave up transcendentals – that is, shared belief in the existence of a knowable moral order outside of the individual's experience. It was a revolution in consciousness, changing our focus from otherworldly to this-worldly, from God to man.

Forgive me, but that doesn't seem so bad.

It wasn't, by any means. The tectonic shift unleashed tremendous creative energy. From it came the Renaissance, the Reformation, the Enlightenment, capitalism, near-miraculous advances in science, democracy – all astonishing achievements, each building on the other.

The course of Western history for the past 700 years has been toward the liberation of the individual and his desires. Modernity, as sociologist Daniel Bell has written, is built on "the proposition that there are no ends and purposes given in nature, that the individual and his or her self-realization is the new standard of judgment, and that one can remake one's self and remake society in an effort to achieve those goals."

What's wrong with that? Individual rights and liberties are the cornerstone of American political order.

Precisely. Even Republicans are liberals in this sense. America is the modern nation par excellence. Here's the catch: Absent a binding source of authority, you can't pick and choose so easily where to draw freedom's line.

The 1960s sexual revolution advanced the frontiers of liberty into the bedroom. Under the guise of privacy rights, contraception and abortion gained constitutional protection. When the California Supreme Court calls same-sex marriage a right because it is "integral to an individual's liberty and personal autonomy," it is only ratifying a deep cultural change that's already taken place.

Is this why banning gay marriage doesn't make sense to young Americans?

Yes, because they've grown up in a culture that presents sex and marriage principally as a matter of personal choice and individual fulfillment. This is a perfectly reasonable ethic for a sensate culture.

We've been moving steadily in this direction for seven centuries. Conservatives can't stop this. Most don't even know where to start.

So what are cultural conservatives supposed to do?

Now? Push for a constitutional amendment carving out a religious liberty exception to federal civil rights laws regarding homosexuality. Otherwise, religious institutions that adhere to traditional sexual morality are going to be strictly penalized once gay marriage is declared to be a federal constitutional right.

In the long run?

Well, it's cold comfort, but this can't go on forever. Sorokin argues that once sensate culture plays itself out, people will have to yield to an ideational model of some sort. It is doubtful that any culture can long survive without strong, traditional families and durable moral norms based in a transcendental source. Our civilization's prosperity has masked its social weaknesses.

Which a deep and prolonged economic crisis would reveal.

You got it. The broader culture is lost. Contemporary moral philosopher Alasdair MacIntyre – no conservative, he – believes we've lost the core convictions required for a politics of the common good. Today's politics, he concludes, amount to "civil war carried on by other means."

Cultural conservatives should focus on strengthening their families and local institutions. Dr. MacIntyre's advice is stark: "What matters at this stage is the construction of local forms of community within which civility and the intellectual and moral life can be sustained through the new Dark Ages which are already upon us."

Grim. It sounds like you're surrendering in the culture war.

I prefer to think of it as retreating to a defensible position.

Rod Dreher is a Dallas Morning News editorial columnist. His e-mail address is rdreher@dallasnews.com.