(Written 24 April 2013)
Suppose two 70-year-olds decide to marry. They can do so, and their marriage will be recognized as valid under the law. And this despite the fact that such elderly couples cannot procreate. But in many places the law does not recognize marriage between same-sex couples who also, obviously, cannot procreate. What is the difference between the opposite-sex and same-sex cases? What is the difference that justifies a difference in legal recognition? (Bear in mind that we are discussing legal recognition of marriage; the issue is not so-called civil unions.) Let us assume that both types of union, the opposite-sex and the same-sex, are guided by the following norms: monogamy, permanence, and exclusivity. So, for the space of this discussion, we assume that the infertile heterosexual union and the homosexual union are both monogamous, permanent, exclusive, and non-procreative.
What then is the difference between the two cases that justifies a difference in treatment? If the only difference is that the one type of union is opposite-sex and the other same-sex, then that is a difference but not one that justifies a difference in treatment. To say that the one is opposite-sex and the other same-sex is to tell us what we already know; it is not to justify differential treatment.
Here is a relevant difference. It is biologically impossible that homosexual unions produce offspring. It is biologically possible, and indeed biologically likely, that heterosexual unions produce offspring. That is a very deep difference grounded in a biological fact and not in the law or in anything conventional. This is the underlying fact that both justifies the state's interest in and regulation of marriage, and justifies the state's restriction of marriage to opposite-sex couples.
There are two points here and both need to be discussed.
The first concerns the justification of the state's involvement in marriage in the first place. It is obvious, I hope, that the state ought not be involved in every form of human association. State involvement in any particular type of human association must therefore be justified. We want as much government as we need, but no more. The state is coercive by its very nature, as it must be if it is to be able to enforce its mandates and exercise its legitimate functions, and is therefore at odds with the liberty and autonomy of citizens. It is not obvious that the government should be in the marriage business at all. The burden is on the state to justify its intervention and regulation. But there is a reason for the state to be involved. The state has a legitimate interest in its own perpetuation and maintenance via the production of children, their socializing, their protection, and their transformation into productive citizens who will contribute to the common good. (My use of 'the state' needn't involve an illict hypostatization.) It is this interest that justifies the state's recognition and regulation of marriage as a union of exactly one man and exactly one woman.
I have just specified a reason for state involvement in marriage. But this justification is absent in the case of same-sex couples since they are not and cannot be productive of children. So here we have a reason why the state ought not recognize same-sex marriage. One and the same biological fact both justifies state regulation and recognition of marriage and justifies the restriction of such recognition to opposite-sex couples. The fact, again, is that only heterosexuals can procreate.
Proponents of same-sex 'marriage' will not be satisfied with the foregoing. They will continue to feel that there is something unfair and 'discriminatory,' i.e., unjustly discriminatory, about the state's recognition of the union of infertile heterosexuals as valid marriage but not of homosexual unions. (Obviously, not all discrimination is unjust.) Consider the following argument which is suggested by a recent article by William Saletan entitled Homosexuality as Infertility. Saletan writes, "People who oppose gay marriage can come to accept it as moral, once they understand homosexuality as a kind of infertility."
The issue is not whether same-sex marriage is moral, but whether it ought to be legally recognized as marriage. That quibble aside, Saletan's piece suggests the following argument:
1. Homosexual couples are infertile just like infertile heterosexual couples are infertile: there is no difference in point of infertility.
2. Infertile heterosexual couples are allowed by law to marry.
3. Like cases ought to be treated in a like manner.
Therefore
4. Homosexual couples ought to be allowed by law to marry.
One can see why people would be tempted to accept this argument, but it is unsound: the first premise is false.
To show this I will first concede something that perhaps ought not be conceded, namely, that the predicate 'infertile' can be correctly applied to same-sex couples. Justification for this concession would be the proposition that anything not F, even if it cannot be F, is non-F. Thus anything not fertile, even if not possibly fertile, is infertile. So same-sex couples are infertile in the same way that numbers and ball bearings and thoughts are infertile.
But even given this concession, there is an important difference between same-sex and opposite-sex couples. The former are essentially infertile while the opposite-sex infertile couples are only accidentally infertile. What the latter means is that there is nothing in the nature of opposite-sex unions to rule out the possibility of procreation. But in the case of same-sex unions, the very nature of the union rules out the possibility of procreation. So (1) in the argument above is false. Homosexual couples are not infertile in the same way that infertile heterosexual couples are. The former are infertile by their very nature, while the latter are not. This difference is what justifies a difference in treatment.
We must of course treat like cases in a like manner. What I have just shown, however, is that the two cases are not alike.
The point is even more clear if we take the view that 'fertile' and 'infertile' are predicates that can be meaningfully applied only to that whose nature includes the power to procreate. Accordingly, same-sex couples are no more infertile than hammers and nails are dead.
We have two interpretive options, and both supply a difference that justifies a difference in treatment.
Option A. Anything that is not fertile is infertile; hence, same-sex unons are infertile. But they are not infertile in the same way that opposite-sex unions are. Same-sex unions are essentially infertile, infertile by their very nature, while opposite-sex unions, when infertile, are only accidentally infertile. (This is why infertile opposite-sex couples can sometimes become fertile through medical intervention.)
Option B. If x is either fertile or infertile, then x has a nature that includes the power to procreate. Hence same-sex couples are neither fertile not infertile.
On either option, Saletan's "Homosexuality is a kind of infertility" is false. This is also clear from the consideration that a couple is called 'infertile' because one of both of the partners is infertile or impotent. But a union of two homosexuals is in most cases a union of two fertile women or of two potent men. To call a homosexual couple 'infertile' is therefore to use 'infertile' in a different way than the way it is used when we call a heterosexual couple 'infertile.' Homosexual couples are infertile because, to put it bluntly, dildos or fingers in vaginas and penises in anuses do not lead to procreation -- and not because of some defect or abnormality or age-induced impairment in the partners.
I have just shown that the (1)-(4) argument for extending the legal recognition of marriage to same-sex unions is not compelling. Nevertheless, some will still feel that there is something unfair about, say, two opposite-sexed 70-year-olds being allowed to marry when homosexuals are not. It may seem irrelevant that the nature of the opposite-sex union does not rule out procreation in the way the same-sex union does. Why do the 70-year-olds get to have their union recognized as marriage by the state when it cannot be productive of offspring?
At this point I would remind the reader that the law cannot cater to individual cases or even to unusual classes of cases. Consider laws regulating driving age. If the legal driving age is 16, this is unfair to all the 13-16 year-olds who are competent drivers. (E.g., farm boys and girls who learned to operate safely heavy machinery before the age of 16.) If the law were to cater to these cases, the law would become excessively complex and its application and enforcement much more difficult. Practical legislation must issue in demarcations that are clear and easily recognized, and therefore 'unfair' to some.
But a better analogy is voting. One is allowed to vote if one satisfies quite minimal requirements of age, residency, etc. Thus the voting law countenances a situation in which the well-informed and thoughtful votes of mature, successful, and productive members of society are given the same weight as the votes of people who for various reasons have no business in a voting booth. We don't, for example, prevent the senile elderly from voting even though they are living in the past out of touch with the issues of the day and incapable of thinking coherently about them. We don't exclude them or other groups for a very good reason: it would complicate the voting law enormously and in highly contentious ways. (Picture armies of gray panthers with plenty of time on their hands roaming the corridors of Congress armed with pitchforks.) Now there is a certain unfairness in this permissiveness: it is unfair to thoughtful and competent voters that their votes be cancelled out by the votes of the thoughtless and incompetent. But we of the thoughtful and competent tribe must simply 'eat' (i.e., accept) the unfairness as an unavoidable byproduct of workable voting laws.
In the same way, whatever residual unfairness to homosexuals there is in allowing infertile oldsters to marry (after my foregoing arguments have been duly digested) is an unfairness that simply must be accepted if there are to be workable marriage laws.
To sum up. The right place to start this debate is with the logically prior question: What justifies the state's involvement in marriage? The only good answer is that state involvement is justified because of the state's interest in its own perpetuation via the production of children and their development into productive citizens. (There is also, secondarily, the protection of those upon whom the burden of procreation mainly falls, women.) It is the possibility of procreation that justifies the states' recognition and regulation of marriage. But there is no possibility of procreation in same-sex unions. Therefore, same-sex unions do not deserve to be recognized by the state as marriage. This is not to oppose civil unions that make possible the transfer of social security benefits, etc.
The infertility argument for the extension of legal recognition to same-sex unions has been neutralized above.