The cases before the Supreme Court regarding same-sex marriage are significant far beyond the issue of whether a small sub-section of less than 3% of Americans deserve government benefits available to heterosexual married couples, or even whether traditional marriage will be damaged by same-sex marriage. That this issue has even arisen at all is testimony to the dysfunctions of modernity that have radiated throughout the culture and created numerous social problems.

The ideology of modernity is that we moderns, armed with superior "scientific" knowledge about human nature and social behavior, can intervene in traditional cultural and social mores, customs, and habits in order to improve or discard them if necessary. The traditions and wisdom of our ancestors, accumulated over centuries, are flawed, based on irrational superstition, ignorance, and prejudices that created injustice and oppression. Understanding the true, "scientific" mechanisms of human and social behavior, we moderns treat society as a machine that can be modified at will in order to make it function more fairly and efficiently. All we need is the power to make these adjustments over the objections of those still mired in outmoded prejudices and irrational superstitions.

This is the belief, of course, that fostered ideologies like communism, whose road to utopia was a dead end littered with millions of corpses. Traditionalist conservatives aren't surprised at such disasters, since they know that a culture is not a machine, but an organism that grows and adapts over time, a repository of all that was learned through the experience and trial-and-error of those who came before us. That's why Chesterton called tradition the "democracy of the dead." The point is not that our culture should be frozen and unchanging, but rather that we give the benefit of the doubt to those traditions that have persisted and suited large numbers of people for a long time. If changes are necessary, we must have powerful arguments and evidence justifying them, and we must be prudent and respect the law of unintended consequences. We must acknowledge the limits to what we know of human nature and behavior and the intricate interactions of a vast diversity of people, each unique and endowed with an unpredictable free will. Given this irreducible complexity, the effects of changes can only be roughly estimated, and will be revealed only over time and among large numbers of people. This prudence is vital, for once instituted, these changes will be difficult to reverse, their malign effects impossible to eliminate. Thus caution must be used before interfering in social institutions.

The redefinition of marriage currently before the court reflects the modern disdain for tradition, and modernity's overweening arrogance about our superior "scientific" knowledge and our power to alter human and social reality to fit our modern prejudices and ideologies. Schooled by the media, popular culture, and dubious social science, many have come to think that homosexuality is a human variation no more significant under the law than hair color or eye color, and so any other point of view can only be the result of irrational prejudice and bigotry. Of course, this belief is unprecedented in human history, for even societies that treated homosexuals better than we think we do never claimed that they weren't anomalous. Even the ancient Greek celebrator of homoerotic attraction, Plato, called sex between males "against nature." Thus our modern view does not reflect advances in scientific knowledge, but rather changing fashion and the efforts of a gay identity-politics lobby that finds social and political traction in casting gays as victims of civil rights inequality.

No more scientifically based are the alleged "studies" that purport to show that children reared by gay couples suffer no adverse effects. As Nelson Lund writes in the Wall Street Journal, professional organizations like the American Psychological Association and the American Academy of Pediatrics claim that scientific research shows no differences between children growing up with gay couples and those raised by heterosexual parents, a claim parroted recently on NPR. But these studies are riddled with compromising flaws such as tiny nonrandom samples, a lack of control groups, and reliance on self-report from gay parents, no more an objective source of information than straight parents' estimations of their parenting skills. Moreover, the most comprehensive study that did use a large randomized sample found several disadvantages for children raised in a household where parents were involved in a gay relationship. But as Lund reports, this study "has been vociferously attacked on methodological grounds by the same organizations that tout the value of politically congenial research that suffers from more severe methodological shortcomings." This is politics, not science. But these pretensions to "science" are typical of the progressive modern, whose ideological preferences and arguments suffer from the irrational prejudices and political self-interests that they routinely claim vitiate the traditionalist perspective.

The fact is, no one knows what will be the long-term effects of such a massive redefinition of society's most important social institution. Supreme Court Justice Elena Kagan thought she scored some points when she demanded that the lawyer defending California's Proposition 8 tell her the exact "harm" gay marriage would cause. Of course, the point is that we don't know how such a social experiment will turn out, or what specific "harm" will follow, no more than we know the benefits. Nor can Kagan or anyone else assure us that no harm whatsoever will result from redefining an institution thousands of years old. That's why prudence is in order. Think back to the "liberationist" movements of the 60s that radically reshaped sexual mores and gender roles, which in turn led to easy divorce, abortion on demand, and guilt-free sexual experimentation. No one at the time, except for repressed and despised neo-puritanical squares, said anything about the possible harmful consequences of such massive social experimentation. We sure know now what they are -- fatherless children, broken homes, illegitimate birth, venereal plagues, sexuality dehumanized in popular culture, women debased into sexual instruments, and a declining birthrate that threatens our economic future.

Some may argue that there have been benefits to these changes that outweigh those costs. Maybe, but at the time all we heard, as we are hearing now with the sentimental idealization of gay marriage, were the boons of personal freedom and equality and self-fulfillment that would follow the rejection of centuries of human wisdom about men, women, and sexuality. Moreover, any calculus of the cost-to-benefit ratio will not be scientific, but one that involves ideology, politics, and subjective preferences. It will depend on certain debatable assumptions about human nature and behavior that no scientist can tell us are true or false. Given how new same-sex marriage is, and given how few children are being raised in such homes, there is very little empirical evidence to help us determine the costs. That means we will in effect be rolling the dice if we transform society's foundational institution.

Finally, if the Supreme Court ratifies this redefinition of marriage, then there will be no rationale for forbidding polygamy or any other configuration of people in a relationship. After all, the couple-centered marriage founded on romantic love and sexual exclusivity is not the universal "natural" form of marriage. In fact, it's an anomaly in human history, a historical development reflecting particular cultural and social conditions that arose in the West. If marriage is a human right, by what secular logic is one kind of marriage privileged over others? Why would same-sex marriage, virtually unknown among human societies, be a "human right," but polygamy, extensively documented in history and prevalent today all over the world, wouldn't?

This incoherence is the consequence of modernity's hubristic belief that human nature is infinitely plastic and can be shaped in any way we want. Determining the limits of such changes and redefinitions will ultimately be determined not by morality, knowledge, or argument, but by sheer power -- just as the proponents of gay marriage want to use the power of unelected, unaccountable judges to impose this monumental transformation on 300 million Americans. And such an abuse of power will be tyrannical, no matter how well-meaning or idealistic the cause for which it is used. That is what's at stake in the litigation over gay marriage -- yet another overreach by the federal leviathan imposing its will over the states and their citizens.