CALIFORNIA'S STATE OF THE UNION TRADITIONAL FAMILY IS ``RATIONAL BASIS''.

Byline: CHRIS WEINKOPF

QUESTION: What do Lawrence Summers, Susan Estrich and gay marriage have in common?

Answer: A lot more than you might think.

Summers, the Harvard University president, created a stir by saying something to the effect that males and females are wired differently. This, while hardly news to anyone with children, was regarded as grand heresy in the academy, where equality and sameness are too often confused.

Then there's Estrich, the syndicated columnist who got into a war of words with Los Angeles Times editors by exposing the dearth of women on the paper's Op-Ed pages. Implicitly, her crusade also boils down to wiring: Because men and women are wired differently, they're likely to perceive the world differently, and thus both voices are needed in the public dialogue.

And that brings us to gay marriage.

Last week, San Francisco Superior Court Judge Richard Kramer ruled that the state constitution contains a previously undiscovered right to same-sex marriage. The state, Kramer decreed, has ``no rational basis'' for limiting marriage to a union of a man and woman.

No rational basis? How about wiring?

The central misconception in the argument for gay marriage is that marriage is a civil right, like voting, something to which all citizens are entitled by birth. But in terms of its legal definition, it serves a different purpose. It's a combination of subsidy and coercion designed to encourage a behavior - the forming of monogamous, procreative and permanent unions - that's deemed beneficial to the whole of society.

The state licenses marriages not so much as an affirmation of a couple's love, but because the traditional family is the cornerstone of a strong society.

There are, to be sure, circumstances when nontraditional arrangements may be the best option - having one loving parent, for example, is superior to having a second, abusive parent under the same roof. But the probability of success is greatest in stable, two-parent households. And because men and women are wired differently - with the strong influence of both important to children's upbringing - the traditional model is the one society has long encouraged, while recognizing the freedom of individuals to set up their own households in whatever way they want.

It's true that some gays and lesbians become parents, even fine ones, and that there's no shortage of dreadful heterosexual parents to be found. But in the aggregate, the traditional home is a kid's best bet. And because heterosexual coupling usually carries the chance of creating new life - while homosexual coupling never does - society has long encouraged sex to fall within the confines of marriage.

That's why sex is known - or at least used to be known - as ``the marital act.'' If there's a chance that children are going to be conceived, it's best that it happen within the context of a stable and committed relationship, one for which there are legal incentives to stay together and heavy costs for dissolving. In the wisdom of the ages, sex, marriage and child-rearing are inseparable.

Judge Kramer is entitled to disagree with that wisdom, but he oversteps in calling it irrational.

Yet the problem for defenders of traditional marriage is that their message sounds terribly anachronistic in our post-sexual-revolution age, which has turned the traditional notion of marriage on its head.

These days, sex outside marriage is common, and child-rearing outside marriage is hardly unusual. The combination of cohabitation, contraception and widespread fatherlessness has, in the public consciousness, all but obliterated the idea that marriage and child-rearing are inextricably linked.

As Judge Kramer, reflecting the ethos of the day, put it: ``One does not have to be married to procreate, nor does one have to procreate in order to be married.''

And what about other qualities traditionally associated with marriage? Monogamy looks like a quaint cultural artifact in the days of ``Desperate Housewives'' and ``American Beauty.'' Permanence? Not in an era of no-fault divorce laws, in which as many as half of all marriages end in divorce, many in the first few years.

This is why defenders of traditional marriage are easily branded - and not always unfairly - as homophobic. The only element of traditional marriage too many are willing to defend is the one that doesn't impinge on their own predilections, namely its restriction to heterosexual couples. For all the worthy efforts to enact constitutional gay-marriage bans across the country, you don't see anywhere near as much desire to bolster marriage-preparation programs, tighten up divorce laws or remake a popular culture that celebrates promiscuity and ``sexual freedom'' over commitment, responsibility and sacrifice.

After all, it's easier to lay the blame for the sad state of modern marriage at the feet of gays and lesbians than to accept personal responsibility.

Gay activists are right when they observe that the institution of marriage is crumbling, and it's heterosexuals who are to blame. They are also right to claim that gay unions won't destroy the institution of marriage. On the contrary, should the day come - and by all indications, it's coming soon - when America puts traditional marriages and gay unions on the same legal plane, it will not be because of some homosexual plot, but because heterosexuals have managed to obscure almost all that was unique and important about traditional marriage in the first place.

But as woefully short of the marriage ideal as we may currently fall, the need for the ideal couldn't be more severe. A generation of fatherless kids, of dysfunctional homes, of children lacking proper care and role models, has taught us that societal tinkering with foundational institutions comes at a steep price. It has taught us that rendering marriage little more than a public blessing of one's private choices is a recipe for social disaster.

Try as we might, we can't make enduring truths disappear. Men and women are different, whether the faculty of Harvard cares to acknowledge it or not. Male and female voices are important, not just in the nation's newspapers, but all the more so in its homes. And no matter how the law is tortured or subverted, marriage and the family will always be the cornerstone on which society stands - or falls.