Burkeans are Trapped
Some people are homosexual. Many of them are involved in loving, stable, committed, nurturing long-term romantic relationships with people of the same sex. Many of those same-sex couples are raising children. These are facts, and, as Dale Carpenter observes, they are not going away. Instead, the numbers are growing.
These facts put the Burkean conservative in a bind. Burkeans argue that people should be cautious about altering an extraordinarily complex system on which large numbers of people depend, as changes could undermine important aspects of the system in unanticipated ways, with disastrous effects for the people who count on the system. It is a reasonable enough concern, kept in perspective, but instead of incorporating it into a more comprehensive doctrine of prudence Burkeans tend to apply it selectively, and to take it as a decisive consideration when they choose to apply it.
In the case of marriage, the Burkean traditionalist argument that is constantly referenced is that we don't want to change the definition of marriage: Marriage = 1 Man + 1 Woman. Same sex marriage would be an unprecedented and risky change that threatens to undermine marriage and family. It would weaken society's commitment to procreation (by allowing a class of people who are biologically incapable of having children together to marry), or it would turn marriage from the norm into a choice (since homosexuals would treat marriage as something optional rather than as what is expected of them, and this attitude would spread), or it would reduce the opprobrium of adultery (since sex outside of marriage would likely be accepted by many gay married couples), or it would weaken the link between parenting and biological relationships, or it would send us down a slippery slope towards polygamy and other kinds of relationships that further threaten the marriage-based social order. What's more, conservatives who oppose same sex marriage or have some apprehensions about homosexuality might view the institution of marriage as corrupted, which would further weaken it. These are risks that we do not want to take, so we should stand pat, refusing to change the institution of marriage to allow homosexuals to marry.
People who make these arguments rarely go on to consider what it means to "stand pat." If they did, they would realize that there is no safe, conservative position that leaves things just the way they were, unthreatened by the kind of radical change that makes Burkeans nervous. The two main alternatives to same sex marriage in public discussions are civil unions and the denial of any systematic kind of legal status to same sex couples, and neither one would conserve the age-old societal institutions of marriage and family.
If same sex couples are denied any formal legal status, then they will be operating outside of the institutions that have survived the test of time in custom and in law. As Brad Plumer (and others) have observed, a whole new set of practices and institutions are going to develop. Millions of couples are going to be living together in long term romantic relationships without getting married (indeed, without any prospect of marriage), and this form of relationship may even spread to the heterosexual community. Millions of children will be raised by couples that are legally incapable of getting married, which could weaken the perceived relationship between marriage and child-rearing. Companies will increasingly grant benefits to their employees' unmarried partners, and they will likely do so whether the partner is of the same sex or the opposite sex, which would serve to reduce the importance of marriage for any couple. What's more, progressives who favor same sex marriage might view an institution that excludes homosexuals as a corrupt institution and choose opt out, which would further weaken marriage. Most of these changes are already well underway, and there is no way to reverse them without repressive, reactionary policies that drastically interfere with the lives of people who are homosexual. This is not the kind of cautious, hands-off approach that Burkean traditionalists adore, and it is probably also politically impossible. And of course it would be terribly wrong.
The other option is to create some new legal status like "civil unions" into which same sex couples can enter, which would grant them most or all of the legal rights of a married couple while denying the status of marriage which will be retained solely for opposite sex unions. On its face, this option appears the least Burkean of all. Instead of keeping the same institution - marriage - and reaching a decision about whether to count homosexuals inside or outside of its scope, they would create an entirely new institution to exist alongside marriage. The result of this compromise position is uncertain. It could stave off both the problems of same sex marriage and the problems of refusing to grant same sex couples a legal status, or it could invite both sets of problems. Civil unions are likely to be an uneasy and unstable compromise, as many homosexuals, progressives, and others will not be satisfied with a separate and unequal institution, while many conservatives who oppose same sex marriage and the "homosexual agenda" would not be happy with any government recognition of same sex relationships, especially not one that differed from marriage in name only. Civil unions are probably also the arrangement that is most vulnerable to slippery slope arguments. If same sex marriage is likely to lead to polygamy and the legitimization within the bounds of "marriage" of other undesirable kinds of relationships, then surely these alternative sorts of relationships are more likely to be recognized by law within the bounds of a lower-status kind of contract like a "civil union." There will be a tension between granting civil unions the importance, significance, and meaning of marriage, and treating them as contracts like any other; the latter view could allow other relationship arrangements to slip in (perhaps even "civil unions" for business partners or old friends), while the former view will make this development nearly as troubling as the "corruption" of marriage.
There is a segment of the population, mostly libertarian (oh, that Posner!), that thinks that the government should get out of the business of granting marriage licenses. The government's role, they say, should just be to enforce unions as contracts like any other, and to provide a minimal set of rights or benefits to partners in such a contract. Marriage is an important, significant, meaningful event, but its significance comes from the people involved, their religious tradition, their friends and relatives, and society at large, not from the government. These people essentially favor "civil unions for all." The government should get out of the marriage business and into the business of granting partnership contracts of all sorts, perhaps including polygamy, open relationships, temporary unions, etc. Some liberals have argued for this sort of view as a compromise that can grant rights to homosexual couples, give them equal status to heterosexual couples, and even present the legal change in a way that would not offend conservatives and religious people. We are elevating religious marriage, they would say, as the only true kind of marriage. The government is just dealing with civil contracts. As the Burkean conservative should be quick to recognize, it is unknown to what extent the significance, meaning, and importance of marriage would withstand this drastic change in the role of the state. Although this position may seem radical now, once an unstable two-tiered system of marriage for heterosexuals and civil unions for homosexuals developed, the sway of this libertarian argument would be likely to increase.
It seems that the Burkean conservative should be highly pessimistic about our future, no matter what way the political winds blow. Is the problem here with homosexuality? No, it is with elevating Burke's insight to the cornerstone of an entire political philosophy. Society is always changing, never more than in our recent history, and often change is drastic and unavoidable (or not worth avoiding). The opportunity for homosexuals to be open about their sexuality and to pursue relationships that can be fulfilling for them is a great achievement of our society, just as the inclusion of women and blacks as (more or less) full members of our society has been a great achievement. Prudence often does not mean focusing on everything that could go wrong and struggling to block change, but rather trying to figure out what options are open to us and to direct the coming changes into one of the most promising channels.
There is an interesting discussion to be had about the structures that marriage and family have had in our history, the recent changes to these institutions, and the forms that they may take in the future (including the places for homosexuals within those institutions). Unfortunately, we have not been having that discussion. Even the thoughtful arguments that go beyond simple slogans and knee-jerk reactions to express doubts about gay marriage only reach the inadequate level of selective Burkean conservatism.