Shelly is getting herself drunk so that she can bring herself to go home with the strange man seated next to her at the bar. One o'clock. Steven is busy downloading pornographic images of children from Internet bulletin boards. Two o'clock. Marjorie, who used to spend every Friday night in bed with a different man, has been binging and purging since eleven. Three o'clock. Pablo stares through the darkness at the ceiling, wondering how to convince his girlfriend to have an abortion. Four o'clock. After partying all night, Jesse takes another man home, not mentioning that he tests positive for an incurable STD. Five o'clock. Lisa is in the bathroom, cutting herself delicately with a razor. This isn't what my generation expected when it invented the sexual revolution. The game isn't fun anymore. Even some of the diehard proponents of that enslaving liberation have begun to show signs of fatigue and confusion.

Liberation Fatigue

Naomi Wolf, in her book Promiscuities, reports that when she lost her own virginity at age 15, there was "something important missing." Apparently, the thing missing was the very sense that anything could be important. In her book Last Night in Paradise, Katie Roiphe poignantly wonders what could be wrong with freedom: "It's not the absence of rules exactly, the dizzying sense that we can do whatever we want, but the sudden realization that nothing we do matters."

Desperate to find a way to make it matter, some young male homosexuals court death, deliberately seeking out men with deadly infections as partners; this is called "bug chasing." At the opposite extreme, some of those who languish in the shadow of the revolution toy with the idea of abstinence — but an abstinence that arises less from purity or principle than from boredom, fear, and disgust. In Hollywood, of all places, it has become fashionable to talk up Buddhism, a doctrine that finds the cure of suffering in the ending of desire, and the cure of desire in annihilation.

Speaking of exhaustion, let me tell you about my students. In the '80s, if I suggested in class that there might be any problem with sexual liberation, they said that everything was fine — what was I talking about? Now if I raise questions, many of them speak differently. Although they still live like libertines, it's getting old. They are beginning to sound like the children of third-generation Maoists.

My generation may have ordered the sexual revolution; theirs is paying the price. I am not speaking only of the medical price of sexual promiscuity. To be sure, those consequences are ruinous: At the beginning of the revolution, most physicians had to worry about only two or three sexually transmitted diseases, and now it is more like two or three dozen. But I am not speaking only of broken bodies. I am speaking, for example, of broken childhoods. What is it like for your family to break up? What is it like to be passed from stepparent to stepparent to stepparent? What is it like to grow up knowing that you would have had a sister, but she was aborted?

Speaking of exhaustion, let me tell you about my students. In the '80s, if I suggested in class that there might be any problem with sexual liberation, they said that everything was fine — what was I talking about? Now if I raise questions, many of them speak differently. Although they still live like libertines, it's getting old. They are beginning to sound like the children of third-generation Maoists.

A young man remarked in one of my classes that he longed to get married and stay married to the same woman forever, but because his own parents hadn't been able to manage it, he was afraid to get married at all. Women show signs of avoidance too, but in a more conflicted way. According to a survey commissioned by the Independent Women's Forum, Norval Glenn and Elizabeth Marquardt of the Institute for American Values found that 83 percent of college women say marriage is a very important goal for them. Yet 40 percent of them engage in "hooking up" — physical encounters (commonly oral sex) without any expectation of relationship whatsoever.

Do you hear a little cognitive dissonance there? Can you think of a sexual behavior less likely to get you into marriage? The ideology of hooking up says that sex is merely release or recreation. You have some friends for friendship and you have other friends just for hooking up — they're called "friends with benefits." What your body does is unrelated to your heart.

Don't believe it. The same survey reports that hooking up commonly takes place when both participants are drinking or drunk, and it's not hard to guess the reason why: After a certain amount of this, you may need to get drunk to go through with it.

Not Designed for It

The fact is that we aren't designed for hooking up. Our hearts and bodies are designed to work together. Don't we already know that?

In "Friends, Friends with Benefits, and the Benefits of the Local Mall," a New York Times Magazine writer who interviewed teenagers who hook up supplies a telling anecdote. The girl Melissa tells him, "I have my friends for my emotional needs, so I don't need that from the guy I'm having sex with." Yet on the day of the interview, "Melissa was in a foul mood. Her 'friend with benefits' had just broken up with her. 'How is that even possible?' she said, sitting, shoulders slumped, in a booth at a diner. 'The point of having a friend with benefits is that you won't get broken up with, you won't get hurt.'"

But let there be no mistake: When I say we aren't designed for this, I'm also speaking of males. A woman may be more likely to cry the next morning; it's not so easy to sleep with a man who won't even call you back. But a man pays a price too. He probably thinks he can instrumentalize his relationships with women in general, yet remain capable of romantic intimacy when the right woman comes along. Sorry, fellow. That's not how it works.

Sex is like applying adhesive tape; promiscuity is like ripping the tape off again. If you rip it off, rip it off, rip it off, eventually the tape can't stick anymore. This probably contributes to an even wider social problem that might be called the Peter Pan syndrome. Men in their forties with children in their twenties talk like boys in their teens. "I still don't feel like a grown-up," they say. They don't even call themselves men — just "guys."

Now, in a roundabout sort of way, I've just introduced you to the concept of natural law. Although the natural-law tradition is unfamiliar to most people today, it has been the main axis of Western ethical thought for 23 centuries, and in fact it is experiencing a renaissance.

Now, in a roundabout sort of way, I've just introduced you to the concept of natural law. Although the natural-law tradition is unfamiliar to most people today, it has been the main axis of Western ethical thought for 23 centuries, and in fact it is experiencing a renaissance.

The hinge concept is design. I said that we're not designed for hooking up, that we're designed for our bodies and hearts to work together. We human beings really do have a design, and I mean that literally — not just a biological design, but an emotional, intellectual, and spiritual design. The human design is the meaning of the ancient expression "human nature." Some ways of living comport with our design. Others don't.

Flouting the Design

From a natural-law perspective, the problem with twenty-first-century Western sexuality is that it flouts the basic principles of the human sexual design. By talking with you about unexpected pregnancies and sexually transmitted diseases, a medical scientist or public-health professional might highlight the consequences of flouting the biological side of the human sexual design. By talking with you about women who wake up crying and men who are afraid to grow up or get married, a natural-law philosopher like me highlights the consequences of flouting the other side of the human sexual design. These two sides of human sexuality must be viewed together.

Now if we are going to be serious about the human sexual design, then we have to attend to its purpose. If it has more than one purpose, then these purposes have to harmonize. The first question to ask about our sexual design, then, is, "What is its purpose, or purposes? What is it for?" I'll answer that question in a moment. Before I can do so, I have to take time out to deal with two inevitable objections to natural law.

The first objection is that it is rubbish to talk about natural purposes, because we merely imagine them; the purposes of things aren't natural; they are merely in the eye of the beholder. But is this true? Take the lungs, for example. When we say that their purpose is to oxygenate the blood, are we just making that up? Of course not. The purpose of oxygenation isn't in the eye of the beholder; it's in the design of the lungs themselves. There is no reason for us to have lungs apart from it.

Suppose a young man is more interested in using his lungs to get high by sniffing glue. What would you think of me if I said, "That's interesting — I guess the purpose of my lungs is to oxygenate my blood, but the purpose of his lungs is to get high"? You'd think me a fool, and rightly so. The purpose of the lungs is built into the design of the lungs. He doesn't change that purpose by sniffing glue; he only violates it.

By talking with you about unexpected pregnancies and sexually transmitted diseases, a medical scientist or public-health professional might highlight the consequences of flouting the biological side of the human sexual design. By talking with you about women who wake up crying and men who are afraid to grow up or get married, a natural-law philosopher like me highlights the consequences of flouting the other side of the human sexual design.

We can ascertain the purposes of the other features of our design in the same way. The purpose of the eyes is to see, the purpose of the heart is to pump blood, the purpose of the thumb is to oppose the fingers so as to grasp, the purpose of the capacity for anger is to protect endangered goods, and so on. If we can ascertain the purpose of all those other powers, there is no reason to think that we cannot ascertain the purpose or purposes of the sexual powers too.

The second objection is that it doesn't make any difference even if we can ascertain the purpose or purposes of the sexual powers, because an is does not imply an ought. This currently unquestioned dogma, too, is false. If the purpose of eyes is to see, then eyes that see well are good eyes, and eyes that see poorly are poor ones. Given their purpose, this is what it means for eyes to be good.

Moreover, good is to be pursued; the appropriateness of pursuing it is what it means for anything to be good. Therefore, the appropriate thing to do with poor eyes is to try to turn them into good ones. If it really were impossible to derive an ought from the is of the human design, then the practice of medicine would make no sense. Neither would the practice of health education.

Consider the young glue-sniffer again. How should we advise him? Is the purpose of his lungs irrelevant? Should we say to him, "Sniff all you want, because an is does not imply an ought"? Of course not; we should advise him to kick the habit. We ought to respect our design. Nothing in us should be used in a way that flouts its inbuilt purposes.

What Is Sex For?

Now that I have warded off the two inevitable objections, let us return to the question of the purpose or purposes of the sexual powers. Common sense tells us that their main purpose is procreation. Since common sense is no longer trusted these days, I'll give an explanation too. Forgive me for sounding like a philosopher, but the explanation is clearer if I use letters as placeholders.

Two conditions must be satisfied before you can say that the purpose of P is to bring about Q, and our answer satisfies both of them. First, it must be the case that P actually does bring about Q. This condition is satisfied because the sexual powers actually do bring about procreation; that's just birds and bees stuff. Second, it must be the case that the fact that P does bring about Q is necessary to explaining why P has come to be — why P exists in the first place. This condition is also satisfied, because the fact that the sexual powers bring about procreation is a necessary part of explaining why we have such powers.

To put this another way, if it weren't for the birds and bees stuff, then it would be mighty hard to understand why we have sexual powers at all. Even a Darwinist must concede the point. (By the way, if you have been worrying about a population explosion, you can stop. In the developed countries, the net reproduction rate is 0.7 and dropping, which means that the next generation will be only 70 percent as large as this one. Demographers are beginning to realize that the looming threat throughout most of the world is not explosion, but implosion.)

Besides procreation, two other purposes are also commonly proposed as the inbuilt purpose of the sexual powers, so let's consider each one. The first suggestion is that the purpose of the sexual powers is pleasure. That their exercise is pleasurable can hardly be doubted, but to call pleasure their purpose does not follow and is deeply misleading.

To see why, consider an analogy between sex and eating. The purpose of eating is to take in nutrition. But eating is pleasurable too. Suppose we were to say, then, that the purpose of eating, too, is pleasure. Then it would seem that any way of eating that gives pleasure is good, whether it is suitable for nutrition or not. Certain ancient Romans are said to have thought this way. To prolong the pleasure of their feasts, they purged between courses. I hope it is not difficult to recognize that such behavior is disordered.

The more general point I am trying to make is that although pleasure accompanies the exercise of every voluntary power, not just sex, it is never the purpose of the power. It only provides a motive for using it — and a dangerous motive, too, which may often be in conflict with the purpose and steer us wrong.

Unitive Intimacy

The other common suggestion is that the purpose of the sexual powers is union: the production of an intimate bond between the partners. This is a much more interesting suggestion, but only half-true. What I mean is that it makes an intriguing point, but that it is not correctly put.

Sociologists Sara S. McLanahan and Gary Sandefur remark in their book Growing Up with a Single Parent that "if we were asked to design a system for making sure that children's basic needs were met, we would probably come up with something quite similar to the two-parent ideal." Of course — for it is designed, though not by us.

Here's what's intriguing about it. We aren't designed like guppies, who cooperate only for a moment. For us, procreation requires an enduring partnership between two beings, the man and the woman, who are different but in complementary ways. But this implies that union isn't a different purpose, independent of procreation; rather, it arises in the context of procreation and characterizes the way we procreate.

A parent of each sex is necessary to make the child, to raise the child, and to teach the child. To make him, both are needed because the female provides the egg, the male fertilizes it, and the female incubates the resulting zygote. To raise him, both are needed because the male is better designed for protection, the female for nurture. To teach him, both are needed because he needs a model of his own sex, a model of the other, and a model of the relationship between them. Mom and Dad are jointly irreplaceable. Their partnership in procreation continues even after the kids are grown, because then they are needed to help them establish their own new families.

Sociologists Sara S. McLanahan and Gary Sandefur remark in their book Growing Up with a Single Parent that "if we were asked to design a system for making sure that children's basic needs were met, we would probably come up with something quite similar to the two-parent ideal." Of course — for it is designed, though not by us.

Another sociologist, Rene Konig, explains in the International Encyclopedia of Comparative Law that children, young ones especially, thrive less in orphanages than in the average family — even when care is taken to make the institutions homelike, and even when, to sociological eyes, they are better organized than an average family in every respect, hygienically, medically, psychologically, and pedagogically.

All this explains why the longing for unitive intimacy is at the center of our design. Without it, procreative partnerships could hardly be expected to endure in the way that they must endure to generate sound and stable families. So, to repeat, achieving union is a real purpose of the sexual powers, but it isn't a purpose separate from procreation; for humans, it comes as part of the procreative package.

Blessed Incompletion

Let me explain a little more about the nature of spousal union. Unitive intimacy is more than intense sexual desire leading to pleasurable intercourse. The sexes are designed to complement each other. Short of a divine provision for people called to celibacy, there is something missing in the man, which must be provided by the woman, and something missing in the woman, which must be provided by the man. By themselves, each one is incomplete; to be whole, they must be united.

We want to transcend our own nature, like gods. We want to pick and choose among the elements of our sexual design, enjoying just the pieces that we want and not the others. Some people pick and choose one element, others pick and choose another, but they share the illusion that they can pick and choose.

This incompleteness is an incredible blessing because it both makes it possible for them to give themselves to each other, and gives them a motive to do so. The gift of self makes each self to the other self what no other self can be. The fact that they "forsake all others" is not just a sentimental feature of traditional Western marriage vows; it arises from the very nature of the gift. You cannot partly give yourself, because your Self is indivisible; the only way to give yourself is to give yourself entirely. Because the gift is total, it has to exclude all others, and if it doesn't do that, then it hasn't taken place.

We can say even more about this gift, because the union of the spouses' bodies has a more-than-bodily significance; the body emblematizes the person, and the joining of bodies emblematizes the joining of the persons. It is a symbol that participates in, and duplicates the pattern of, the very thing that it symbolizes; one-flesh unity is the body's language for one-life unity. (The next two paragraphs are closely indebted to the Oxford philosopher John Finnis.)

In the case of every other biological function, only one body is required to do the job. A person can digest food by himself, using no other stomach but his own; he can see by himself, using no other eyes but his own; he can walk by himself, using no other legs but his own; and so on with each of the other powers and their corresponding organs. Each of us can perform every vital function by himself, except one. The single exception is procreation.

If we were speaking of respiration, it would be as though the man had the diaphragm, the woman the lungs, and they had to come together to take a single breath. If we were speaking of circulation, it would be as though the man had the right atrium and ventricle, the woman the left atrium and ventricle, and they had to come together to make a single beat.

Now, it isn't like that with the respiratory or circulatory powers, but that is precisely how it is with the procreative powers. The union of complementary opposites is the only possible realization of their procreative potential; unless they come together as "one flesh" — as a single organism, though with two personalities — procreation doesn't occur.

Sexual Landscape

Why do I spend time on these matters? I do so in order to emphasize the tightness with which different strands are woven together by our sexual design.

Children change us in a way we desperately need to be changed. They wake us up, they wet their diapers, they depend on us utterly. Willy-nilly, they knock us out of our selfish habits and force us to live sacrificially for others; they are the necessary and natural continuation of the shock to our selfishness that is initiated by matrimony itself.

Mutual and total self-giving, strong feelings of attachment, intense pleasure, and the procreation of new life are linked by human nature in a single complex of purpose. If it is true that they are linked by human nature, then if we try to split them apart, we split ourselves. Failure to grasp this fact is more ruinous to our lives, and more difficult to correct, than any amount of ignorance about genital warts. It ought to be taught, but it isn't.

The problem is that we don't want to believe that these things are really joined; we don't want the package deal that they represent. We want to transcend our own nature, like gods. We want to pick and choose among the elements of our sexual design, enjoying just the pieces that we want and not the others. Some people pick and choose one element, others pick and choose another, but they share the illusion that they can pick and choose.

Sometimes such picking and choosing is called "having it all." Having it all is precisely what it isn't. A more apt description would be refusing it all, insisting on having only a part, and in the end, not even having that.

Think of our sexual landscape as a square or quadrant with four corners, A, B, C, and D. Over in corner A are people — mostly men — who buy into the fantasy that they can enjoy greater sexual pleasure by instrumentalizing their partners and refusing the gift of self. By doing so, they fall pell-mell into what has been called the "hedonistic paradox": The best way to ruin pleasure is to make it your goal.

Pleasure comes naturally as a byproduct of pursuing something else, like the good of another person. When I talk with students, I illustrate the point with a Mick Jagger song they've all heard, although they think the Rolling Stones are a bunch of geezers. The song is "I Can't Get No Satisfaction." Nobody who has ever listened to the song imagined that Jagger suffered from a shortage of sex. The problem was that all that satisfaction wasn't satisfying anymore.

In corner B of the quadrant are other people — mostly women — who try to substitute feelings of union for union itself. We catch a hint of how common this is in the debasement of the language of intimacy. In today's talk, "I was intimate with him" means "I had sex with him," no more and no less. This euphemism is used more or less interchangeably with another one, "I was physical with him," and that tells you all you need to know.

The parties have engaged in a certain transaction with their bodily parts. There may have been one-flesh unity — in other words, their bodies may have been acting as a single organism for purposes of procreation — but there has not been one-life unity, because that would require mutual and total self-giving. Even so, the bodily transaction produces feelings of union, because that is what it is designed to produce.

For them, too, childlessness is a loss, but the decisive factor is not sterility, but deliberate sterility. In the natural course of things, if we willfully refuse the procreative meaning of union, then union is stunted. We are changed merely from a pair of selfish me's to a single selfish us.

One confuses these feelings with the things that they represent and are meant to encourage, wondering afterward why everything fell apart. After all, you "felt so close." You "seemed so committed." You "had such a good thing going." Yes, you had everything except the substance of which these feelings are designed to be a sign.

In corner C of the quadrant are couples, who imagine that by denying the procreative meaning of sexuality, they can enhance its unitive meaning — that by deliberately avoiding the so-called burden of children, they can enjoy a deeper intimacy. It doesn't work that way. Why should it? The unitive capacities of the spouses don't exist for nothing; they exist for their procreative partnership.

That is their purpose, and that is the matrix in which they develop. Children change us in a way we desperately need to be changed. They wake us up, they wet their diapers, they depend on us utterly. Willy-nilly, they knock us out of our selfish habits and force us to live sacrificially for others; they are the necessary and natural continuation of the shock to our selfishness that is initiated by matrimony itself.

To be sure, the spouses may try to live sacrificially for each other, but by itself, this love turns too easily inward. Let no one think that I am referring to couples who are childless through no fault of their own. For them, too, childlessness is a loss, but the decisive factor is not sterility, but deliberate sterility. In the natural course of things, if we willfully refuse the procreative meaning of union, then union is stunted. We are changed merely from a pair of selfish me's to a single selfish us.

In corner D of the quadrant are people who think in exactly the opposite way. Instead of supposing that they can affirm the unitive meaning of sexuality without the procreative, they imagine that they can affirm the procreative meaning of sexuality without the unitive. The full shock of this way of life is not with us yet, but our technology allows it, and in most jurisdictions, so does our law.

Meet Amber, who lives alone, shares social occasions with Dave, in whom she has no sexual interest, and sleeps occasionally with Robert, in whom she has no social interest. Amber wants a child, but she doesn't want the complications of a relationship, and besides, she doesn't want to be pregnant. Where there's a will, there's a way. She contracts with Paul as sperm donor, Danielle as egg donor, Brooke as incubator, and Brian as visiting father figure to provide the child with "quality time."

Let us set aside our feelings and attend to what has happened here. Among humans, procreation takes place within the context of a unitive relationship. To destroy the unitive meaning of the procreative act is to turn it into a different kind of act. It's no longer procreation, but production; the child is no longer an expression of his parents' love, but a product. In fact, he has no parents. He was orphaned before his conception. His relation to his caretaker is that of a thing bought and paid for to the one who bought and paid for it.

The Counterrevolution

I've developed just four themes in this article; allow me to review them. The first is that we ought to respect the principles of our sexual design. Just as those ways of living that flout the bodily aspects of our design sicken and kill us, so those ways of living that flout the emotional, intellectual, and spiritual aspects of our design ruin us and empty life of meaning.

Let the sexual revolution bury the sexual revolution. Having finished revolving, we arrive back where we started. What your mother — no, what your grandmother — no, what your great-grandmother told you was right all along. These are the natural laws of sex.

The second theme is that the human sexual powers have a purpose. As the purpose of the visual powers is to see and the purpose of the ingestive powers is to take in nourishment, so the purpose of the sexual powers is to procreate. This purpose is not in the eye of the beholder; apart from this purpose, we would have no way to explain why we have them. Moreover, if we try to make use of the sexual powers in ways that thwart and violate this purpose, we thwart and violate ourselves.

The third theme is that the human design for procreation requires marital and family life. For guppies, it doesn't; they manage to procreate without them. For us, however, it does. To put this another way, we are made with a view to marriage and family, and fitness for them is one of our design criteria. No one invented them, no one is indifferent to them, and there was never a time in human history when they did not exist.

Even when disordered, they persist. Spouses and family members who are divided by disaster commonly undertake Herculean efforts to reunite with each other. Marriage and family are not merely apparent goods but real ones, and the rules and habits necessary to their flourishing belong to the natural law.

The final theme is that the spousal bond has its own structure, which both nourishes and is nourished by these institutions. Because it has its own structure, it has its own principles. Among these principles are the following: Happiness cannot be heightened by sexually using the Other; conjugal joy requires a mutual and total gift of Self. Feelings of union are no substitute for union; their purpose is to encourage the reality of which they are merely a foretaste. The procreative and unitive meanings of sexuality are joined by nature; they cannot be severed without distorting or diminishing them both.

These principles are the real reason for the commands and prohibitions contained in traditional sexual morality. Honor your parents. Care for your children. Save sex for marriage. Make marriage fruitful. Be faithful to your spouse.

Let the sexual revolution bury the sexual revolution. Having finished revolving, we arrive back where we started. What your mother — no, what your grandmother — no, what your great-grandmother told you was right all along. These are the natural laws of sex.