In recent months, I have come to change my opinions slightly regarding the gay marriage issue (read my post from a while back on the issue here). First, I have become more sympathetic to the side opposing the licensing of unions of two people of the same-sex. And second, I have come to the recognition that as much as the institution of marriage has suffered in the last 40-some years, gay-marriage will not cause it to decline even further. Rather, gay marriage, is the next logical step in the disintegration of heterosexual marriage.
I believe that the anti-gay marriage crowd is correct in saying that the political/social institution of marriage (I want to separate it from the religious institution... though historically, the two were not so separate and the religious institution also reflected the same values about marriage as did the political/social) is to a great extent about begetting and raising children. We recognize this in the laws that we have. Why do we not allow cousins to get married? Because if they have kids, it would likely be disastrous for those children's' health due to the harms of mixing genes from the same gene-pool. In this case, we recognize that two people who get married would naturally want to have kids. Otherwise, we could allow cousins to get married but bar them from having kids. Why also do we not allow four people or six people to get married? For precisely the same reason. Since physically, only two people of different genders can beget children, we recognize that the primary responsibility for raising those children must lie with those two people, not four who happen to have an agreement of "love and commitment."
So, in light of this, Sen. Rick Santorum's (R-PA) statement, last year (that we would have to legalize incest, polygamy, etc), does not seem all that outrageous. Even to an atheist such as myself. What does all of this have to do with gay marriage one might ask (as one socialist did on a cold evening near Washington Square Park... he was sorry he got in my path to sign his harebrained petition)? Well, the thing is, that based on my cursory reading of biology textbooks, I have concluded that only two people of different genders can, together, beget children. So if we recognize, as we had to above, that marriage as a social/political institution is primarily (or at least, largely) a reflection of the partnership's unique and primary responsibility of begetting and raising children, then since homosexuals cannot beget children within their partnership, they are missing a significant component of marriage. So, in that sense, their unions are less than the marriage between heterosexuals in the traditional sense.
But this does not mean that I oppose, today, granting licenses to gay couples to get married. The reason for this, is that, like the author of this article (thanks to Instapundit for the pointer), I believe that we no longer have a society in which most heterosexuals understand marriage and sexual relations in the traditional sense. It seems that for most people, the choice of having children or not having children has become a lifestyle choice completely detached from marriage, rather than a natural consequence and reflection of the union. This is largely due to the advent of reliable birth-control, which allows people to make that choice. For most heterosexuals, sharing in common domestic affairs (such as living together), is also separate from marriage. Most people now live with the person they marry before actually getting married.
Some of these trends, I think are negative, and others just neutral. But all of them do point to changing attitudes towards the institution of marriage. I don't think that these are things that we can change. For example, I do believe, that birth control is an important innovation of modern society. Even traditional Catholics who pay lip-service to opposing contraception still have their own version of it in natural family planning (sure, there is an argument to be had whether NFP does contradict Catholic doctrine or not, but at least, they do realize the benefits of not having 15 kids, 10 of whom die at childbirth). Similarly, I think that much of the weakening of attitudes about marriage were a cost to the improvement of the lot of women over the years. Bearing children became a lifestyle choice because women started working on a large scale -- and not just as teachers or librarians. Hence, contraception, became vital in being able to plan and control when to have children. Since women bore the greatest burden in childrearing, having children made careers prohibitive for women. I do not believe that we can turn back the clock on our views of marriage without severely hurting women's right, nor should we. I also do not think that this is politically feasible. I think that this is a permanent change in the way our society views marriage. Again, I am not saying that these views are all bad or all good. I think that some of them are harmful and others are neutral or actually beneficial.
As such, I do not think we are justified in keeping gays from enjoying the same marriage light option that we allow countless heterosexual couples. We do not go into a household and un-marry a couple if it is a childless marriage for non-medical reasons. As such, the government, has no legitimate state interest in discriminating between the two for what amounts to no essential difference between heterosexuals who do not accept the traditional understanding of marriage and homosexuals.
Finally, we can not leave these questions up to the states as some have suggested. Because of the full faith and credit clause of the U.S. Constitution (Art. 4, Sec. 1), which reads:
"Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof."
UPDATE: Ok, I just did some research and found that the Supreme Court has held that the Full Faith and Credit Clause is not completely set in stone, for there is something called the "public policy exception" which says that if one state's legal decree contradicts another state's public policy in a significant way, that state does not have to recognize the original state's decree as legally binding. For a good discussion of this, go here. In that case, I would favor leaving the gay-marriage issue up to the states.