How should we respond to the hookup culture? A number of concerned parents, pastors, and professors from all sides of the religious and political spectrum have expressed concern about the sexual culture that today’s young people inhabit. Some scholars, such as sociologists Mark Regnerus, Jeremy Uecker, and Kathleen Bogle, have published value-neutral analyses that aim to assess current trends and save us from common misperceptions. In empirical terms, they tell us how and why the sexual economy hurts its actors. Others, such as Laura Sessions Stepp and Donna Freitas, have offered more personal—and, for Freitas, spiritual—analyses of problems and possible solutions in modern sexual culture. Interestingly enough, these authors don’t write as traditionalists or social conservatives. They aren’t advocating purity rings or “modest is hottest.” Instead, they seek to help young people make more responsible sexual decisions. Not surprisingly, though, their counsel often aligns with a traditional conception of sexuality and monogamy, even if not perfectly. The science shows that more commitment and fewer sexual partners tend to make people happier.

But what about those who think that morality requires a bit more of us? How can they persuade young people that reserving sexual intimacy for marriage is the right thing to do? In his book On the Meaning of Sex, popular author and political philosopher J. Budziszewski attempts to make such an argument on the basis of human nature and natural law. He begins with an anecdote from teaching. During a classroom discussion of Aldous Huxley’s Brave New World, one of his students, Harris, said he found the characters disgusting. When pressed, Harris clarified that he had no problem with their sexual habits: “Sex doesn’t always have to mean something,” he insisted. What he found disgusting was their factory production of human beings.

But, Budziszewski argues, holding those two positions is not logically consistent:

It shouldn’t have bothered Harris unless procreation is something that ought to take place in the loving embrace of the parents. . . . Moreover, since Harris was revolted that the aspiration to children could ever be separated from the aspiration to union, it would seem that he recognized that these two meanings aren’t merely sometimes joined together, but that they are joined whenever we have sex. . . . Apparently sex means something to us even if we don’t admit to ourselves that it does.

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That last sentence conveys Budziszewski’s goal and style of argumentation: He wants to draw attention to the reader’s gut feelings and instincts that may have been trained away by education or social conditioning. He wants to help them see what they know, even if they don’t know that they know it.

After some well-laid-out arguments about function, purpose, and natural law, Budziszewski argues that our bodies and actions have natural purposes. This means that some actions, such as those necessary for sexual union, mean something, whether we want them to or not. To put it another way, they say something, even if that is not what we want them to say: “A bodily action is like a word; we mean things to each other no less by what we do than by what we say. . . . To crush your windpipe with my thumbs is to say to you, ‘Now die,’ even if I tell you with my mouth, ‘Be alive.’ To join in one flesh is to say, ‘I give myself to you in all that this act means,’ even if I tell you with my mouth, ‘This means nothing.’” What sex means is total gift, a union of selves instantiated through bodily union, and it cannot but help mean that. By acting against this nature, which we cannot change, we do damage to ourselves and others.

Budziszewski further argues that human nature entails complementary differences between men and women. He notes that these differences are similar across cultures, both in terms of what people think they are and what they think about them. “Mark it up as another victory of quantitative social science,” he writes: “We can now confirm by counting that what everyone used to know without counting really is true.” He then explores how the particular characteristics of men and women make them attractive—in short, what we mean when we say that someone is sexy. Budziszewski thinks we mean that we find their manliness or womanliness desirable. Womanliness, for instance, “isn’t something she contrives, but something that glows from her. . . . The most compelling and believable signs of being a nice person to marry, make love with, and have children with are the ones that arise spontaneously. They are an outward glory given by an inward and invisible reality. A beautiful woman cannot help giving off such radiance, because it is an effect of what she really is.” Beauty conveys something deeper and more holistic than raw sexual appeal.

Similarly, spousal love is not a matter of feelings but an act of the will. Enchantment is a feeling of emotional infatuation, the moment of “wow” when she enters the room. Love, by contrast, is really about charity, which Budziszewski defines as “a permanent commitment of the will to the true good of the other person.” Erotic charity is a mode of charity bound to one person, and sexual intercourse is a particular act of this charity that fuses two selves together in the union of their flesh. Because love is not about enchantment, but charity, it is an act of the will, not a feeling. Therefore, Budziszewski argues, “it is something that one decides to do, and it can be promised.” To the many young people who claim that permanent, exclusive marriage is impossible because you can’t promise feelings, he would say yes—but marriage is not a promise of feelings.

Not surprisingly, Budziszewski calls for embracing sexual purity, which, he makes clear, is a matter of pursuing goods—goods that will be useful and helpful for marriage—not fleeing from them. Its temporary “no’s” enable one to give a full “yes” at the right time. He sees sexual purity as coming in both masculine and feminine flavors: “One awakens the feminine intuition of something that must be guarded; the other, the masculine sense of something that must be mastered.” And he extols the virtues of purity: decorum, “the conduct befitting the dignity of man as a rational being”; modesty, which “expresses respect for the fragility of this dignity . . . [and avoids] provoking appetites that people should be trying to moderate”; and temperance, finding order and the mean in one’s actions.

Throughout the book, Budziszewski resists invoking God or anything beyond rationally accessible premises. More accurately, he hints at such ideas without developing his hints, nor has he explained why every chapter begins with a quotation from John of the Cross. In the conclusion, though, he argues that sex points to and is ultimately about God: “Nature points beyond herself. She has a face, and it looks up. . . . ultimately, human love makes sense only in the light of divine love. The point is not that divine love means something and that human love doesn’t. Human love means so much, because divine love means still more.” In a variation on C.S. Lewis’s argument for the existence of God based on desire, he notes that even when we love well, mortal love is not enough. Since no human longing is made in vain, this unfulfilled natural desire must point toward a supernatural lover.

But taking this argument into religious waters poses the question of which audience Budziszewski hopes to reach. And that poses the larger question of how effective his efforts—not to mention the broader efforts of like-minded religious believers—actually are. If he wants to strengthen the faithful as they navigate young adulthood, he might well succeed. To be sure, far too many young religious men and women have followed the cultural lead and abandoned chastity. If On the Meaning of Sex gave them better reasons for it, that alone would be a great feat. But how is he to persuade students who press with further questions or actively oppose his views on principle? Budziszewski’s occasionally chivalric language might go over well with young Chestertonians, but many young adults would balk at passages like this one:

When we do attempt the journey back to the commonwealth of sense, we will meet trolls and enchanters on the way. They will obstruct passage, demand tribute, and try to lure us into byways and bogs. But why should that discourage us? We are already begrimed and bewitched. The first thing to do is open our eyes, grasp hold of the nearest branches, and pull ourselves out of the ooze. Odd knights we! Having made ourselves muddy and ridiculous, we may as well journey with a smile.

Likewise, the Arthurian metaphor of the Siege Perilous for a woman, her sexuality, or her reproductive organs is not going to fly outside more traditional Christian circles, and even there it might receive tenuous support.

Inquisitive students will desire more proof that sex has to mean what Budziszewski thinks it means—and why it cannot mean what they might want it to mean. His passages about sexual beauty offer an attractive vision of what it means to be human, but can they pierce the carapace of wounded, ironic disdain? He discusses sexual differences with nuance and care, and many young adults would no doubt find resonances of his words in their lives, but, albeit unfairly, a good number will dismiss it as patriarchal and outmoded.

How then can those who agree with Budziszewski try to show young adults a more excellent way? There are few easy answers, but On the Meaning of Sex’s strengths show where to begin: by offering an eloquent, engaging description of the beauty of men, women, and sexuality. Moreover, it seeks to show young people the wisdom of their desires and repugnance. It tries to preserve good intuitions and gently check misunderstandings, to show them what their hearts know, even if unwittingly. It also hands on the wisdom of our forebears with care and winsomeness. Of course, those who believe that chastity leads to flourishing must also demonstrate it with their lives. But arguments are necessary as well, and both the style and the content of On the Meaning of Sex offer a good place to find them.