There have been a lot of claims that the marriage equality movement somehow threatens "traditional" marriage.
Exactly what is the tradition? Upon closer look, we find that our concepts of marriage have changed enormously over time. Marriage as we currently know it, based on the free association and choice of the couple, is really quite modern, maybe 150 years old. And the traditions aren't really what the anti-equality want to admire. Let's review some "traditions".
*Polygamy Although in Western cultures, we haven't practiced polygamy in some time (except, ironically, for the Mormons), there is a strong tradition of polygamy in many cultures even today. It's quite common in many parts of the world. In fact, if you go back to Biblical times, polygamy is clearly Biblically countenanced. However, it is also associated with inequities (both to women, of course, and the unpartnered men) and is socially destabilizing. And it's clear no one (on either side) is arguing for the return of polygamy!
*Then there's the issue of partner choice. Even today, marriage is really a legal contract. Traditionally, that contract was between families. Women were essentially property, to be sold with a bride price or a dowry to form alliances and bring benefits. And, arranged marriages are still very common in many countries today. It wasn't until the 1800's that the concept of marriage between romantic partners really became accepted, that marriage for love was the ideal.
*What about the tradition that marriage is for children? That one left us in the 1960s, when sex and marriage became totally decoupled by the "sexual liberation" movement. In fact, around 40% of births in the US are to unwed mothers. Moreover, many couples choose not to have children at all; there's no requirement for fecundity. Since we let the infertile and the elderly marry, we've agreed that marriage ≠ childbearing. So, procreation is no longer the reason for marriage. Another tradition already gone.
*Traditionally, marriage is between people of the same race. That tradition was Biblically justified by conservatives. However, in 1948, in Perez v. Sharp, the SCoCal found that
"the essence of the right to marry is the right to join in marriage with the person of one's choice."while in 1967, when SCOTUS finally caught up to California, they averred that Marriage is one of the "basic civil rights of man," and
To deny this fundamental freedom on so unsupportable a basis as the racial classifications embodied in these statutes, classifications so directly subversive of the principle of equality at the heart of the Fourteenth Amendment, is surely to deprive all the State's citizens of liberty without due process of law. .....Under our Constitution, the freedom to marry, or not marry, a person of another race resides with the individual and cannot be infringed by the State.
*Of course, a huge change to "traditional marriage" comes through women's rights. It really isn't until recently, well within the last century, that women gained rights to property and consideration in their own right. It used to be that a woman had to have her husband's permission to apply for a credit card or to obtain contraception. She had no right to independent property. She could be beaten, or raped, by her husband and this was perfectly legal. In fact, it wasn't until 1993 that the last US state recognized the concept of marital rape. I don't know about you, but I don't find much to celebrate in that kind of tradition.
*Lastly, there's the availability of divorce. In our modern society in the US, most states now allow "no-fault" divorce, where blame or fault need not be assigned one partner. Rates of divorce are high, leading to the estimate that approximately 50% of marriages will be dissolved. It's important to remember that this dissolution is a legal event, not done by the church that might have married the couple. However, biblical strictures against divorce abound, far more common than any mention of same-sex relationships. The Roman Catholic church prohibits remarriage following divorce but most other denominations are more (dare I say) liberal. In fact, there is a distinct irony that those protesting most strongly against marriage equality are often those who countenance divorce, or even have themselves divorced (rates are particularly high for evangelicals). "Traditional" marriage being "for life" is therefore no longer the case. There is an implicit recognition that with our lengthened lifespans, not every couple will grow in the same way, and there is no longer an expectation that people must remain in unhappy partnership.
So, what we can see is that our modern concept of marriage is constantly evolving. From rejecting polygamy, to allowing the partners to choose one another, to separating marriage from child-bearing, to allowing people to marry across racial lines, to recognizing women as equal partners, and recognizing that marriages may not last a lifetime we've seen an enormous amount of change, and much of it is quite modern (within the last 150 or even the last 25 years). Pro-equality supporters do not want to change anything in our modern understanding of marriage, except a pronoun.
Importantly, we don't want to change one of the most important aspects of marriage: that of fidelity. Let's just look at marital fidelity. Seems the loudest exponents of "traditional marriage" have the hardest time with its most important tradition. Yes, I'm thinking of David Vitter, Larry Craig, John Ensign, and Mark Sanborn, and their ilk. And I'm comparing them to people like Del Martin and Phyllis Lyon and other GLBT couples who have really been together through thick and thin despite every obstacle. Truly, who is a better exponent of "traditional marriage"?
Half of the people in this country already have the right to marry a woman of their choice. Why shouldn't everyone?