Marriage is primarily defined by a solemn commitment and perhaps some related auxiliary conditions, like a psychological and physical ability to at least minimally fulfill the commitment. Here is a question one may ask about this commitment:
- Is there any positive sexual content to the marital commitment?
Question 1 is of both theoretical and practical interest. If the answer to 1 is negative, then it is hard to resist the suggestion that there is nothing problematic about same-sex marriage. After all, if there is no positive sexual content to the commitment, then it seems that same-sex couples can make exactly the same defining commitment that opposite-sex couples can. Moreover, Scriptural and philosophical arguments about the wrongness of same-sex sexual activity cease to be directly relevant to the question of same-sex marriage, since given a negative answer to question 1, same-sex marriage does not imply same-sex sexual activity or a commitment thereto.
On the other hand, if the answer to Question 1 is positive, then a natural second question is:
- Does the sexual content concern a particular kind of sexual activity, and, if so, what kind?
I don't want to address question 2 here. I want to focus on question 1.
Suppose we answer question 1 in the negative. Then there is a sub-question:
- Is there any negative sexual content to the marital commitment?
Suppose first that we answer both question 1 and question 3 in the negative. Then there is no sexual content to the marital commitment at all. What, then, is the content of the commitment? It is presumably something about a kind of intense friendship. It is something like a commitment to love, care for and cherish through thick and thin. But now we have a problem: This kind of commitment fails to distinguish marriage from other relationships. It would be deeply controversial to say that it is permissible for two siblings to marry. But it would not be deeply controversial to say that it is permissible for two siblings to solemnly commit to love, care for and cherish through thick and thin. Hence, to solemnly commit to this is not the same as marrying. Moreover, many parents do, though typically not solemnly (e.g., they rarely make vows), promise their children to be there for them no matter what, even after the child is grown up. And we would neither be very surprised nor morally troubled if an adult child reciprocated that commitment—and we certainly would not think that this was tantamount to a marital commitment. Nor were the Three Musketeers married to each other.
But perhaps the marital commitment includes a commitment to a certain kind of deep emotional sharing, a sharing that goes beyond that which close siblings unproblematically engage in. But just as a view on which the commitment has coitus in its content would exclude same-sex couples from marrying, a view on which the commitment has deep emotional sharing as its content would exclude persons who are not very emotional or not capable of deep emotional sharing from marrying. And the latter exclusion is more problematic. We have a cultural stereotype that many men are not interested in deep emotional sharing with their wives. But if marital commitment included a commitment to such sharing, it would be a consequence of this stereotype that either they aren't married to their so-called wives or they are unfaithful to their marital commitment. This is not a plausible consequence. And stereotypes aside, there surely are very large numbers of people who are not interested in deep emotional sharing, and yet marry. And when they marry, it is implausible to suppose that they commit themselves to the deep emotional sharing they are uninterested in.
Moreover, given that some siblings (especially identical twins) are very close, and yet not at all incestuously involved, and we could imagine that the siblings commit themselves to that closeness, it would be very difficult to require a marital commitment to an emotional closeness that goes beyond those cases of fraternal closeness without requiring a commitment to something that few married couples have or are even capable of.
Supposing a commitment to deep intellectual communion would be even worse at distinguishing the marital relationship from other relationships.
There does not, then, appear to be much hope of specifying in an entirely non-sexual way what the marital commitment is. The view that the answers to both Questions 1 and 3 are negative is untenable.
Suppose, howevere, we allow that the answer to Question 3 is positive but that to Question 1 is negative. On this view, the marital commitment contains on the positive side a commitment to a certain kind of deep friendship, and on the negative side a commitment to abstaining from sexual activity with anyone else. But if a certain kind of deep friendship didn't do the job of defining the content of the marital commitment, neither will adding a commitment to abstinence from sexual activity with others. After all, plausibly, one way of committing oneself not to engage in sexual activity with anyone other than one's spouse-to-be is to commit oneself not to engage in sexual activity with anyone at all. But, surely, if a commitment to deep friendship was not sufficient for a marital commitment, adding vows of general sexual abstinence (I almost said "vows of celibacy", but "celibacy" in the traditional sense of the word means abstinence from marriage) will not help.
Perhaps, though, this is unfair. Maybe the content of the commitment needs to be, at least semi-explicitly, that one will abstain from sexual activity with anyone else, and to commit oneself to something that entails this (such as committing oneself to total abstinence) will not do. But I think this won't help. Take the case of two siblings who promise to always be there for each other, to love and cherish one another. And then they break up their promise of general celibacy into two: "Nor will we ever engage in sexual activity with anyone else. And certainly not with one other (ugh!)." That would be weird, yet surely they would not become married just because they broke up their promise of general celibacy in this way. But once they so broke it up, they did in fact explicitly commit not to engage in sexual activity with anyone else.
Thus, if a commitment to some deep friendship won't do the job for the content of the marital commitment, adding a commitment to abstain from sexual activity with others will not help. Therefore, the answer to Question 1 is positive, whether or not the answer to Question 3 is positive or negative. A marital commitment must include some sexual content or else we will either exclude some obvious cases of marriage (e.g., people incapable of deep emotional sharing) or count as marriage what is clearly not (people committing non-maritally to one another) or both.
This is not enough to answer questions about the possibility of same-sex marriage. To answer those questions, Question 2 would need to be addressed. My view is that the only fully defensible answer to Question 2 involves coitus, and hence excludes same-sex marriage, but I am not arguing for that in this post.