Recently, the California Supreme Court overturned legislation that put an effective ban on gay marriage. Some of the first couples were married in the last few days.

Naturally, this has created quite a stir, and these couples' newfound civil rights hang precariously upon a proposed amendment to the California constitution. This amendment would etch into the highest legal writ in the Golden State that marriage is a union of a man and a woman.

It is an old argument, and one I have seen oft repeated on the internet in recent days, that gays should not be given the legal right to marry simply because they cannot be married. By definition, marriage is a heterosexual institution, and has traditionally been so for the entire span of human history. Some posit that gays and lesbians can have their "civil unions," but whatever it is, it is not and cannot be marriage. To call it that would be to redefine the term "marriage" itself.

Those who make such arguments are absolutely right, and yet cannot be more wrong.

Traditionally, marriage is the union of a man and a woman. It is a bond that joins two families through the sexual congress of a couple and paves the way for the creation of a new family. Marriage is a way of regulating the human need for procreation in a way consistent with the religious and social values of the culture, sanctifying the bond and conveying a sense of responsibility upon the parents. It would take a quantum leap to reframe the ritual as the sanctification of the union of a couple who could not possibly procreate.

Yet, this very redefinition has already occurred.

In ancient times, and in much of the world today, marriages were and are arranged by the parents of the brides and grooms-to-be, often before the children reached puberty. Marriage was a way of combining family assets and assuring a promising future for one's children and grandchildren, especially for women, who had little authority of their own. Attraction, affection, "love" were supposed to be the result of, not the impetus for, a successful marriage.

But the modern, Western notion of marriage is not the traditional one. Modern marriage is explicitly entangled in the idea of romantic love: that daring notion that we love from our hearts—from impulse—and not from duty. We choose our mates, not our parents. And a good choice of mate is not a matter of convenience, in our culture: it is a matter of attraction, of affection, for the individual person. Marriage is no longer the sanctification of an arranged coupling for breeding purposes. Marriage is the sanctification of the love of one individual for another—sexual, romantic, amorous love.

It cannot be denied that there are couples of a man and a man who truly love one another, and couples of women and women who love each other just as much. And if the modern bond of marriage is a bond of love and not a bond of duty, why should we call the union of a man and a man, or a woman and a woman, anything other than marriage? Love does not discriminate between heterosexuals and homosexuals: it is the exclusive province of neither. Who are we to tell consenting adults that they are in love with the wrong kind of person? And who are we to take away their right to celebrate and consecrate that love as the cornerstone of a new family?