Thus, marriage - for all its flaws and miseries - has evolved to promote, support and nurture that basic necessary unit. If the state goes out of its way to make marriage attractive, it is because marriage is so difficult and, in many ways, unnatural. It is far more natural for humans, animals that we are, to enjoy gratification whenever and wherever than it is to settle for decades into a system of monogamy.
That many fail, however, is no justification for eliminating the goal of the nuclear, male-female, monogamous family, which has worked well if not perfectly for most of civilized memory.
One might argue logically for extending certain benefits to same-sex couples, but marriage isn't necessary to that end. Surely next-of-kin issues for corporate and death benefits can be managed outside of marriage. Moreover marriage isn't only about civil rights. Marriage is mostly the institutionalization of an ideal that we honor in observation of a higher natural order.
The fact that some homosexual households already include children isn't sufficiently compelling to redefine marriage either. To extend marriage rights to gays on that basis presupposes that raising children in homosexual households is just as good as raising children in heterosexual homes with two parents.
Surely no one needs a scientific study, or God forbid, a poll, to "prove" what is written in our human DNA - that sons and daughters need the qualities of both their parents, Mother and Father.
That said, it is unlikely that a few thousand married homosexuals will topple civilization, as some have warned. Or that homosexual men will suddenly opt to marry ducks, as Bill "No Spin" O'Reilly recently proposed.
But this is not an insignificant social experiment to be tittered over in cappuccino bars. Making homosexual unions equal to heterosexual unions - the superior natural order of which cannot be disputed - is not just a small step for equality. It is a gargantuan leap from a natural order that has served mankind throughout civilized human society.
We should look long and hard before we leap.