Cultural conservatives can't be too happy about the country's growing tolerance for gay marriage and legal marijuana, both of which a slim majority now supports. This erosion of traditional moral codes, they fear, will put America on the highway to Gomorrah.

But removing government from the business of enforcing morality doesn't mean that individuals will celebrate their liberation by smoking crack and throwing orgies. It means that they'll become active agents in choosing their own morality.

The late Robert Bork famously warned in his 1996 jeremiad Slouching Toward Gomorrah that America would succumb to moral decadence if Uncle Sam didn't censor pornography and promote traditional marriage. Eighteen years earlier, Alexander Solzhenitsyn, a literature Nobelist who served time in the Gulag for criticizing Stalin, offered an identical prognosis in a Harvard speech. American society, the anti-communist hero lamented, "has turned out to have scarce defense against the abyss of human decadence."

Conservatives no longer speak in such overwrought tones, but that doesn't mean their worries about America's moral decline have vanished. New York Times columnist Ross Douthat recently wrote that gay marriage will further sever the link between marriage and procreation, presumably opening the door to incest, polygamy, and other sexual arrangements. Likewise, former drug czar Bill Bennett has exhorted the administration to go after Colorado and Washington, which recently legalized marijuana, lest they pave the way for harder drugs.

The assumption driving such worries is that individuals are inherently hedonistic and, absent the threat of punishment in this world and damnation in the next, they'll seek only their own pleasure and ignore family and community, ripping the social fabric.

But life doesn't work that way. Individuals don't simply discard an old order in favor of no order. They look for a new order that better accommodates their personal goals and social needs.

There is no better evidence for this than the modern recalibration of the feminist movement. In the '60s, when feminists such as Alice Walker were comparing motherhood and family to slavery, alarmed conservatives warned of rampant abortions, wholesale child neglect, the devaluation of fathers, and family breakdown. For a while such fears seemed borne out by soaring divorce rates, increasing pro-choice sentiment (which I share), and Murphy Brown–style celebrations of single motherhood.

Fast-forward a couple of decades. Walker's own daughter, Rebecca, has condemned her mother's views and become an evangelist for motherhood and family. And many indices are now trending conservative. Divorce peaked at 50 percent in the 1980s and has dropped about 10 percentage points since then. A 2013 USA Today/Gallup poll shows that support for unregulated abortion is declining, with a slight majority now describing itself as pro-life, a startling reversal from a decade ago.

Such trends have prompted the former neoconservative thinker Francis Fukuyama to observe that "Great Disruptions" produced by social movements such as feminism don't necessarily lead to a net "decrease in social capital." Instead, the capital —cultural norms and mores—gets reconstituted, and even expands.

Why? Freedom allows individuals to sort through existing social rules, discarding ones that don't work and embracing ones that do. In a free market, early adopters signal to others whether the cost of a new invention is worth the return. Likewise, in a free society, social mavericks who defy conventional morality indicate to others whether risking social opprobrium is worth the personal gain.

There is no a priori reason to believe that widespread polygamy and heroin use, for example, would pass this social test. "Flexibility of moral rules…makes gradual evolution and social growth possible," observed F.A. Hayek, a libertarian but also a great defender of tradition. This, he added, "allows experience to lead to modifications and improvements."

William F. Buckley exhorted conservatives to "stand athwart history" and yell stop. But conservatives can save their breath. Free individuals are perfectly capable of yelling themselves.