Now that the Supreme Court has taken the decision about same-sex marriage out of the hands of the American people, those of us who believe in marriage have to think about the long-term effort to restore a true understanding of marriage in our nation.

The first step is to clarify what marriage is so that we can explain it to others in a coherent way. Although there is no one way to do this, there are fundamental elements that are a necessary part of any definition.

In this essay, I merely provide one definition of marriage. My goal here is not to “prove” that this is marriage (though I offer some thoughts on each condition), nor is it to engage in a refined academic analysis of the question. I simply want to offer a relatively succinct statement of what marriage is, so that ordinary people who want to defend marriage have a clear baseline from which to understand and respond to developments in our society.

Ten Key Features of Marriage

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When we say we are “defining” marriage, we are not saying that we choose to view marriage as being such-and-such, that this is what we want marriage to be. Marriage is not a conventional arrangement that society defines for itself. It is “pre-political”—it has a nature that is independent of human desires, beyond the reach of human modification. While some aspects of marriage may vary in different times and places, nevertheless, there are certain “non-negotiables,” without which marriage would not be an intelligible institution distinct from ordinary contracts.

What is marriage? Here’s my rough and ready definition: Marriage is a formal social/legal bond constituting a union of life, and particularly an exclusive sexual union, established by free consent, between one man and one woman, for life, oriented essentially toward the procreation and education of children and a life of faithful mutual support.

Let’s break down this definition by identifying ten key features.

1) Marriage is a formal social-legal bond, recognized by society. This public bond has the effect of creating legal obligations and rights between husband and wife, parent and child, and family and community. This recognition is necessary for the stability of the union, especially for the benefit of any children the marriage produces, but also for the benefit of the spouses.

2) Marriage is a community, or communion, or union of life. Through it, the spouses reciprocally give themselves to each other, sharing a common life. This sharing occurs at all the various levels of human life: physical, financial, emotional, moral, intellectual, and spiritual. The comprehensiveness of this sharing makes marital love the deepest sort of friendship.

3) Marriage is sexually exclusive. The vow of fidelity removes these two people from “the sexual marketplace,” so that they are no longer available to others as possible sexual partners. This is necessary for family stability, ensuring the emotional commitment of the bond, and checking the powerful disordering force of sexual jealousy. This norm also prevents spouses from having their attention diverted away from the children that this marriage has produced.

4) Marriage is established by free consent, because a bond of this kind (a personal commitment of self) and magnitude (for the whole of life) cannot be fairly imposed on one person by others. In fact, the free consent of the spouses to marital union is precisely what constitutes—establishes, creates—the bond.

5) Marriage is between two people—it entails monogamy. This is necessary because the ability of marriage to achieve its goal of full, mutual self-giving cannot be achieved with more than two people. A commitment to two or more people necessitates a divided and diminished commitment, a withholding of shared life. Moreover, monogamy also respects the equality of the spouses, since attempting to have such an intimate relationship with more than one person could never result in truly equal, much less fully self-giving, relationships. And it is necessary for family harmony and stability, since multiple spouses (and children by different spouses) will inevitably tend to beget various forms of competition within the family.

6) Marriage is between a man and a woman; it is a bond based on sexual complementarity. This is a major part of the sexual urge, which is not just physical. The sexual urge aspires to a certain kind of completion of the spouses, by providing access to (integrating into one’s life) different dimensions of human life (notably, the distinctive virtues and capacities typical of the other gender) that would not be achieved by one man or woman alone. The complementary qualities of men and women are important, not only for spouses themselves, but especially for children, who have access to a greater range of parental virtues and capacities than would generally be true of marriages without sexual complementarity.

7) Marriage is for life. This is, above all, for the stability of the framework for raising children, whose sense of security is intimately tied to the bond between the parents. Even parental obligations require a commitment for life (not just during the youth of the children) because what we do now is influenced by what we think of the future. (Think of the analogy of a baseball or golf swing, in which the follow-through is essential to the overall power of the swing. You have to commit to that follow-through at the beginning of the swing; without it the swing is much weaker.) The stability of the bond is also important for the spouses themselves, since a lifelong bond powerfully promotes the incentives to invest their best efforts in the marriage.

8) Marriage is oriented toward the procreation of children. This is what is really distinctive about the conjugal union, what it does that nothing else can do so well. In fact, what constitutes the distinctive marital unity of spouses is not their physical unity (which, strictly speaking, is never more than closeness or contiguity), but above all, their being, together, a single reproductive unit or principle (even in cases where their union doesn’t actually result in a child). In other, recently developed forms of procreation (in test tubes or through surrogacy or cloning), a human being is “manufactured” and does not result from an act of love. These techniques often, in practice, dilute the connection and responsibility of at least one biological parent.

9) Marriage is oriented toward the rearing and education of children, because human children develop over a long period of time, and the biologically-based parental commitment is by far the strongest, most reliable bond to ensure that development. No other people will have the same biological tie to the child, and thereby the same emotional investment. Because of this deep biological tie, the parents have the greatest natural incentive to do the best they can, in the education of their children. (Biological ties don’t guarantee parental fulfillment of obligations, of course, and children sometimes have to be raised by people other than their parents; but, on the whole, there is no other bond which can be relied on to provide a greater likelihood that children will be raised by people emotionally committed to them.)

10) Marriage is oriented toward a life of mutual spousal support, at all levels. This includes the ordinary obligation to support and care for each other (physically, emotionally, financially), in the midst of the joys and difficulties of life. The highest form of this support is the commitment to help one’s spouse grow in personal excellence or virtue, and therefore happiness.

A particularly important point to note (often lost sight of today) is that the procreation and education of children and the life of mutual support are not optional “alternative” ends, each pursuable in isolation from the other. They are rather intimately intertwined. The procreation and education of children constitutes a significant portion of the lives of the spouses—their greatest “joint project”—and calls forth their mutual cooperation, thereby contributing profoundly to their personal unity in marriage. The mutual, faithful help and support that the spouses provide each other in the ups and downs of their shared life constitutes the very context in which they conceive, bear, give birth to, raise, and educate their children.

The life of mutual support provides the stability and virtuous example that children need; on the other hand, were a marriage merely oriented to mutual support and not procreation, no social-legal bond (with attendant rights and responsibilities) would be necessary.

Falling Short in Marriage

It will not escape notice that not everything that is called “marriage” looks like this. To see why this is so, it is important to understand the nature of a definition. Especially when we are dealing with a natural and developmental being—a being that is not a product of human art and that only achieves a fuller realization of its capacities over time—we don’t define it simply by looking for some “least common denominator” in the things we call by that name.

If we did that with “human beings,” for instance, then our definition could not include the fact that human beings walk on two feet—because there are many human beings (young children) who don’t, in fact, walk on two feet, but crawl. Our definition has to focus on the fully developed, paradigmatic form of a being. So we look at healthy adult humans, not children.

Many real-life instances of the beings we are defining fall short of the full definition. Many instances of what is commonly called “marriage” are undeveloped or inadequate, falling short, in significant ways, of what a true, or good, or fully developed form of marriage is. Human weakness, ignorance, and selfishness constantly intrude in people’s lives—their married as well as their personal lives, and in social life as well as individual lives—and so, in many respects, concrete, real-life marriages do not live up to what marriage is. They can fail to do so in various ways.

Some features can vary in intensity, or qualitatively. For example, the unity or sharing of life can be greater or less, and the level of mutual support can vary. In these cases, there are real marriages, but they vary qualitatively.

Some features are clear in some cases, more obscure in others. Whether there is free consent or coercion is sometimes clear, but there are other cases that are grey areas.

Other features either exist in the marriage or they don’t: sexual complementarity and monogamy, for instance. The absence of sexual complementarity or monogamy (including marriages in which one person has previously contracted a valid, lifelong marriage bond with another person) means that an essential condition for marriage is simply missing, and so marriage is impossible. Such “unions” (for all their good intentions and genuine affection) are something other than marriage.

Finally, if marriage is based on consent, then that consent has to be consent to marriage, and not something else. Consent to a union that deliberately excludes sexual exclusivity, or permanence, or any possibility of children, or any mutual aid and support, is not consent to marriage. Here, too, we can talk of some kind of de facto union, but not of marriage, strictly speaking.

The Importance of Marriage

We have to take the question of what marriage is seriously. What many people in our country are fighting for is not merely “traditional” marriage—that is, “old” marriage, or some way marriage “used to be,” or is supposed to have been. (There was no “golden age” of marriage to which we must return. Marriage has always been wounded in various ways, though worse in some times than others.) What is worth fighting for is simply marriage—real marriage.

We should not offend others needlessly by insisting that people who have good-faith, sincere beliefs that they are married, are not really married. At the same time, though, marriage is important, and we cannot simply let other people define it for us. Recognizing what marriage is, we must, as tactfully as we can, hold that reality up as a truth for everyone.