Activists seeking to redefine marriage typically claim that it is unfair—even arbitrary—for law and public policy to continue to honor the historic understanding of marriage as the conjugal union of husband and wife. Believing that marriage has a degree of malleability that our legal tradition has heretofore failed to recognize, they maintain that “excluding” same-sex partners from marriage violates a moral right possessed by every individual to marry a person of one’s choice (with that person’s consent). Defenders of conjugal marriage reply (in part) that marriage is not malleable in the ways that their opponents suppose. It is by nature oriented to procreation, and so defining marriage as a male-female union is not unjust discrimination. On a sound understanding of marriage, they argue, it is no more unfair to “exclude” same-sex partners from marriage than it is to “exclude” three (or more) polyamorous sexual partners from marriage. Indeed, it is not accurately characterized as exclusion at all.
Those who support defining marriage in such a way as to include same-sex partnerships deny that marriage has any intrinsic relation to procreation. When striking down Proposition 8 (which re-established conjugal marriage under California law after it had been invalidated by that state’s supreme court), Judge Vaughn Walker curtly argued: “Never has the state inquired into procreative capacity or intent before issuing a marriage license; indeed, a marriage license is more than a license to have procreative sexual intercourse.” The same argument was advanced earlier by Chief Justice Margaret Marshall in her majority opinion in Goodridge v. Department of Public Health, the ruling that struck down Massachusetts’ conjugal marriage law; replying to the contention that marriage’s primary purpose is procreation, Marshall confidently replied that:
This is incorrect…. General Laws c. 207 contains no requirement that the applicants for a marriage license attest to their ability or intention to conceive children by coitus. Fertility is not a condition of marriage, nor is it grounds for divorce. People who have never consummated their marriage, and never plan to, may be and stay married.
But this argument—that since infertile couples can marry, marriage is not oriented to procreation—is radically unsound.
In this essay we will show how to answer the argument denying an intrinsic link between marriage and procreation, and we will explain why the state is obliged, for the sake of moral truth and the common good, to recognize and protect marriage as a man-woman community naturally oriented to procreation. We will show that this argument presupposes a false dichotomy regarding marriage: that it must be either (1) a mere means in relation to procreation as its extrinsic end, or (2) a partnership that, though perhaps more emotionally intense than most friendships and typically marked by the presence of sexual relations, is nonetheless like other forms of friendship inasmuch as it bears no intrinsic relationship to procreation. And we will describe a better understanding of marriage—one that is in fact historically embodied in our law and in the philosophical traditions supporting it. On this understanding, marriage is a sexual union of the type that is especially apt for, and would naturally be fulfilled by, having and rearing children together, but whose value, precisely as such a relationship, is intrinsic (as an irreducible aspect of integral human fulfillment) and not merely instrumental (as it would be if marriage were properly understood as only a means to procreation and the rearing of children).
The key is to understand the specific type of community marriage actually is—in particular, how it is bodily, sexual, and of a type that would naturally be fulfilled by procreation. In every society, we find something like the following type of relationship: men and women committed to sharing their lives together, on the bodily, emotional, and spiritual levels of their being, in the kind of community that would be fulfilled by procreating and rearing children together. That such a distinctive type of community—marriage—does exist in every society is undeniable. There are, of course other relationships similar in some ways to marriage. For example, men and women may cohabit, regularly have sex together, and view the possibility of having children as a possibly attractive optional “extra,” or perhaps instead as a burden to be avoided. Or, by contrast, two or more individuals may form an alliance for the sake of bringing up children—two sisters, for example, or several celibate religious men or women. But these relationships are not marriages, and no society recognizes them as marriages. Marriage is that type of community that is both a comprehensive unity (a unity on all levels of the human person, including the bodily-sexual) and a community that would be fulfilled by procreating and rearing children together. Moreover, there is an intrinsic link between these two aspects of the community; the comprehensive (and therefore intrinsically sexual) relationship is fulfilled by, and is not merely incidental to, the procreating and rearing of children.
These points can be clarified. First, the bodily, sexual aspect of the relationship is part of and is inherently linked to the other aspects of the marital union. The sexual communion of a man and a woman establishes a real, biological union—a one-flesh union is an accurate description of it—for in this act they are biologically a single agent of a single action. Just as an individual’s different organs—heart, lungs, arteries, and so forth—perform not as isolated parts, but in a coordinated unity to carry out a single biological function of the whole individual (circulation of oxygenated blood), so too in coitus the sexual organs of the male and those of the female function in a coordinated way to carry out a biological function of the couple as a unit—mating. Hence coitus establishes a real biological union with respect to this function, although it is, of course, a limited biological union inasmuch as for various other functions (e.g., respiration, digestion, locomotion) the male and female remain fully distinct.
Now, the human body is part of the personal reality of the human being, and not an extrinsic instrument of the conscious and desiring aspect of the self. So the biological unity just described can be a truly personal unity and a part (indeed, the biological foundation) of the comprehensive, multi-leveled (biological, emotional, rational, volitional) union that marriage distinctively is. When a man and woman make a commitment to each other to share their lives on all levels of their being, in the type of community that would be fulfilled by cooperatively procreating and rearing children, then the biological unity established and renewed in sexual intercourse is the beginning or embodiment of that community we know as marriage. Unlike other forms of friendship, the marital community is structured by norms of monogamy, exclusivity, and the pledge of permanence, partly because of the intrinsic link between it and procreation. The sexual communion of spouses is the bodily component proportionate to, indeed part of, the kind of multi-leveled personal community they have consented to in marrying.
Second, such a community is extended and naturally fulfilled by procreating and rearing children together. The child is the concrete fruit and expression of their marital commitment and their love for one another; indeed, each child born of the marriage is the union of the spouses made concrete and prolonged in time. So the cooperative rearing of their children does not establish a new type of relationship, but rather deepens and naturally fulfills the relationship that they have established precisely in marrying. Rearing children is to tend to the marriage, to cultivate its fruit, to serve the good of the parents’ marriage by and through each act of service to each child. As a form of human relationship, marriage is indeed, then, intrinsically oriented to procreation—but not as a mere means in relation to an extrinsic end. The union of the spouses to one another in a relationship whose distinctive structure is what it is because of its aptness for procreation and the rearing of children is no mere instrumental good, but is rather good in itself—an intrinsic fulfillment of those united in the relationship. And it is for this reason that a marriage is and remains a marriage—a true marriage—even if procreation does not result and even if the spouses know that it will not result. With or without children, spouses are in a relationship of the type that is especially apt for procreation and would naturally be fulfilled by their having and rearing children together—their children (if they were to have children) would be embodiments of their marital communion. The marital communion of the spouses is good in itself, and as such provides a non-instrumental reason for conjugal relations, whether or not they are capable of conceiving children; but it is also naturally fulfilled when it becomes part of a larger community, the family.
Given these two points regarding the nature of marriage, it is clear why marriage is the union of sexually complementary spouses. Same-sex partners, whatever the character or intensity of their emotional bond, cannot form together the kind of union that marriage is. To marry, a couple must, in principle, be able to form a real bodily union—not just an emotional and spiritual union. Same-sex couples are unable to do this: the sexual acts that persons of the same sex can perform on each other do not make them biologically one, and so cannot establish the bodily foundation for the multi-leveled union that is marriage. And to marry, a couple must form the kind of communion that would be naturally fulfilled by conceiving and rearing children together. Same-sex couples cannot form this type of union: they (two or more) can form sexual arrangements, and can also form alliances for child-rearing, but the one relationship is distinct and not inherently linked to the other.
Also, given these points about marriage, it is easy to see that infertile opposite-sex couples can form a true marital union. They are able to fulfill the two essential conditions just mentioned for marrying. First, infertile opposite-sex couples can form a biological unit—they can mate (that is, they can perform the kind of act that results in procreation when conditions extrinsic to their conduct obtain). Second, infertile opposite-sex couples can form the kind of bodily, emotional, and spiritual union of precisely the sort that would be naturally fulfilled by procreation and rearing of children together—even though, in their case, that fulfillment is not reached.
It is sometimes objected that infertile couples cannot biologically unite, since their act is not in fact capable of procreating—they cannot (it is objected) perform an act that is procreative in kind, which is necessary for a biological union. However, no couple can directly or simply choose to procreate. The only thing any couple can directly do regarding procreation is to perform the kind of act that will lead to procreation, provided other conditions extrinsic to their conduct obtain. (Thus, children are not products of their parents’ sexual acts: rather, parents should rightly view them as gifts that supervene upon their bodily expression of love in their sexual union.) So, opposite-sex couples who are infertile can perform precisely the same kind of act that fertile couples can perform. In both cases, they fulfill the behavioral conditions of procreation. And so the sexual intercourse of an infertile couple, no less than that of a fertile couple, unites them biologically: they mate, even though, in the case of the infertile couple, procreation will not result. In each case, their sexual act can consummate or embody their marriage.
So, the state’s granting marriage licenses only to opposite-sex couples is based on the nature of marriage and does not constitute unjust discrimination. The state grants a license to do X only to someone presumptively capable of doing X. It is no more unjust discrimination to deny marriage licenses to couples of the same sex than to twelve-year olds, to those already married, or to polyamorous groups of three or more sexual partners: in each case, the license is denied simply because the individuals in question are unable to form with each other the kind of union that marriage is.