‘More Sex Is Safer Sex: The Unconventional Wisdom of Economics’

By STEVEN E. LANDSBURG

MORE SEX IS SAFER SEX

It's true: AIDS is nature's awful retribution for our tolerance of immoderate and socially irresponsible sexual behavior. The epidemic is the price of our permissive attitudes toward monogamy, chastity, and other forms of extreme sexual conservatism.

You've read elsewhere about the sin of promiscuity. Let me tell you about the sin of self-restraint.

Consider Martin, a charming and generally prudent young man with a limited sexual history, who has been gently flirting with his coworker Joan. As last week's office party approached, both Joan and Martin silently and separately entertained the prospect that they just might be going home together. Unfortunately, Fate, through its agents at the Centers for Disease Control, intervened. The morning of the party, Martin happened to notice one of those CDC-sponsored subway ads touting the virtues of abstinence. Chastened, he decided to stay home. In Martin's absence, Joan hooked up with the equally charming but considerably less prudent Maxwell - and Joan got AIDS.

When the cautious Martin withdraws from the mating game, he makes it easier for the reckless Maxwell to prey on the hapless Joan. If those subway ads are more effective against Martin than against Maxwell, they are a threat to Joan's safety. This is especially so when they displace Calvin Klein ads, which might have put Martin in a more socially beneficent mood.

If the Martins of the world would loosen up a little, we could slow the spread of AIDS. Of course, we wouldn't want to push this too far: if Martin loosens up too much, he becomes as dangerous as Maxwell. But when sexual conservatives increase their activity by moderate amounts, they do the rest of us a lot of good. Harvard professor Michael Kremer estimates that the spread of AIDS in England could plausibly be retarded if everyone with fewer than about 2.25 partners per year were to take additional partners more frequently. That would apply to three-fourths of all British heterosexuals between the ages of 18 and 45.

A cautious guy like Martin does the world a favor every time he hits the bars. In fact, he does the world two favors. First he improves the odds for everyone who's out there seeking a safe match. The second favor is more macabre, but probably also more significant: If Martin picks up a new partner tonight, he just might pick up an infection as well. That's great. Because then Martin goes home, wastes away in solitude, and eventually dies - taking the virus with him.

If someone has to get infected tonight, I want it to be Martin rather than Promiscuous Pete, who would probably infect another twenty people before finally dying.

I'm always glad to see guys like Martin in the bars. When he takes home an uninfected partner, he diverts that partner from a potentially more dangerous liaison. When he takes home an infected partner, he diverts that partner from giving the virus to someone who might spread it far and wide. Either way, I sure hope he gets lucky tonight.

Sadly, none of this makes for a good pickup line. You're unlikely to get very far with an approach like "You should sleep with me so you can get infected, die, and take the virus with you." That would be like saying "You should sell your leaf blower so your neighbors' lawns stay cleaner" or "You should stay seated at the ballpark so everyone else can see." The whole point is that what's good for the group can be bad for the individual, and that's why we get bad outcomes.

If multiple partnerships save lives, then monogamy can be deadly. Imagine a country where almost all women are monogamous, while all men demand two female partners per year. Under those circumstances, a few prostitutes end up servicing all the men. Before long, the prostitutes are infected; they pass the disease on to the men; the men bring it home to their monogamous wives. But if each of those monogamous wives were willing to take on one extramarital partner, the market for prostitution would die out, and the virus, unable to spread fast enough to maintain itself, might well die out along with it.

The parable of the monogamous wives has a more profound moral than the legend of Martin and Joan, because it shows that even on a society-wide level, increased promiscuity could retard the epidemic - at least in principle. But what about practice? That's where Professor Kremer's research comes in. With plausibly realistic assumptions about how people choose partners, his work shows that the moral remains essentially the same. When your relatively demure neighbor experiences a rare moment of rakishness, he really is doing his part to combat the deadly scourge.

That's one reason why you should root for Martin to have sex with Joan. Here's another: they'll probably enjoy it.

Enjoyment should never be lightly dismissed. After all, reducing the rate of HIV infection is not the only goal worth pursuing; if it were, we'd outlaw sex entirely. What we really want is to minimize the number of infections resulting from any given number of sexual encounters. That's the same as maximizing the number of (consensual) sexual encounters leading up to any given number of infections. Even if Martin fails to deny Maxwell a conquest, he can at least make someone happy.

If you are a monomaniac whose goal is to minimize the prevalence of AIDS, then you should encourage Martin to have more sex. But if you are a sensible person whose goal is to maximize the difference between the benefits of sex and the costs of AIDS - then you should encourage Martin to have even more sex.

To an economist, it's crystal clear why people with limited sexual pasts choose to supply too little sex in the present: their services are underpriced. If sexual conservatives could effectively advertise their histories, HIV-conscious suitors would compete to lavish them with attention. But that doesn't happen, because conservatives are hard to identify. Insufficiently rewarded for relaxing their standards, they relax their standards insufficiently.

When you take a new sex partner, you bear some costs and you reap some benefits. Those are your business. You also impose costs and benefits on others, and those are everyone else's business. If you have a history of reckless promiscuity, that's a cost. Everyone's fishing for partners in a great communal stream and you've polluted that stream just by entering it.

But if you've always been cautious and selective, you're likely to raise the average quality of the partner pool. Just by jumping into the stream, you make it purer. Thanks to you, everyone who goes fishing for a partner tonight has a better chance of catching a safe one.

Like any other communal stream, the stream of partners has too many polluters and too few volunteers to clean it up. The reason factory owners don't do enough to protect the environment is that they're insufficiently rewarded for environmental protection (or insufficiently punished for neglecting it). They reap some rewards (even factory owners like clean water and clean air), but most of the benefits go to total strangers. Likewise, the reason Martin might not do enough to fight the scourge of AIDS (by sleeping with Joan) is that, while he certainly would reap some rewards (such as sexual pleasure), many of the benefits would go to Joan's future partners, and their future partners.

The flip side of the analogy is that Martin's chastity is a form of pollution - chastity pollutes the sexual environment by reducing the fraction of relatively safe partners in the dating pool. Factory owners pollute too much because they have to breathe only a fraction of their own pollution; Martin stays home alone too much because he bears only a fraction of the consequences.

The pollution analogy is so powerful that it dictates the moral of virtually any story you could tell. To conclude that Martin's coupling with Joan slows the epidemic, you have to make some assumptions about what Joan and Maxwell and all of their potential partners would be doing if Martin stayed home. But to conclude that Martin's coupling with Joan makes the world a better place (where "better" accounts for both the costs of disease and the benefits of sex), you don't need any of those assumptions. It is a quite general principle that when goods (such as Martin's sexual services) are underpriced, they are undersupplied.

Here, then, is what we know:

When sexual conservatives relax their standards, benefits spill over onto their neighbors. That alone is enough to tell us that the world would be a better place if we could loosen these people up a little.

There is, however, more than one way for the world to become a better place. Maybe the epidemic slows down. Maybe people enjoy more sex. Maybe the epidemic speeds up, but people enjoy so much more sex that it's worth it.

Pure theory - in the guise of the communal-stream principle - tells us that at least one of those good things must happen. Professor Kremer's research suggests that both good things happen: we get more sex and less illness.

If all you want to do is slow down the epidemic, Professor Kremer's research says that more sex is a good thing. But if you want to maximize the excess of benefits over costs, then even more sex is an even better thing.

So: how do we encourage Martin (and others like him) to have more sex?

I wish this book could nudge him in the right direction, but sadly, there's no reason why it should - even if he reads and understands it completely. (Don't let that stop you from buying him a copy, though.) Martin has already chosen the activity level that's right for him. He's not likely to adjust that level just because he learns that a bunch of strangers - namely, Joan's future partners and their future partners - would appreciate it.

Martin, being human, tends to concentrate on what's good for Martin, not what's good for the society he lives in. You can make a polluting factory owner understand that he's hurting his neighbors, but that's not the same as convincing him to stop.

So we need something more effective than mere education. Extrapolating from their usual response to environmental issues, I assume that liberals would attack the problem of excessive sexual temperance through coercive legislation. But as a devotee of the price system, I'd prefer to encourage good behavior through a well-designed system of subsidies.

In other words, we could pay people to have more sex with more partners. But that's not ideal, because we don't want everyone to have more sex with more partners. Maxwell, for example, is quite oversexed enough as it is. The problem is to subsidize Martin's sexual awakening without simultaneously subsidizing Maxwell's genuine excess.

So we should pay people for having sex only if they are relatively inexperienced. Unfortunately, that doesn't work very well either - not as long as Maxwell can lie about his past and keep a straight face long enough to collect his handout.

What we need is a reward that Martin values and Maxwell doesn't - like, say, a library card. I'm guessing that Maxwell, with his busy social life, doesn't spend a lot of time at the library.

That's a definite improvement, but it's still imperfect. When Martin arrives at the circulation desk looking appropriately smug and disheveled, how can the librarian know whether he's really fulfilled his coital obligations or is just putting on a good show?

Let's try again: We need a reward that's of no value to Martin unless he actually has sex. And as before, it should be something the cautious Martin values more than the promiscuous Maxwell does.

I can think of only one reward that fits both criteria: free (or heavily subsidized) condoms. To reap the benefits of a free condom, Martin has to have sex. And Martin probably values a free condom considerably more than Maxwell does. Here's why: Martin's almost surely not infected yet, so a condom has a good chance to save his life. Maxwell, by contrast, knows he might have the virus already, so a condom at this point is less likely to make a difference. Subsidized condoms could be just the ticket for luring Martin out of his shell without stirring Maxwell to a new frenzy of activity.

As it happens, there is another reason to subsidize condoms. Condom use itself is underrewarded. When you use a condom, you protect both yourself and your future partners (and your future partners' future partners), but you are rewarded (with a lower chance of infection) only for protecting yourself. Your future partners can't observe your past condom use and therefore can't reward it with extravagant courtship. That means you fail to capture all the benefits you're conferring. As a result, condoms are underused.

In other words, people use too few condoms for the same reason they have too little sex. When Martin has sex with Joan, that's good for Joan's future partners. When Martin uses a condom, that's good for Martin's future partners. In neither case do the future partners get a fair opportunity to influence Martin's behavior.

It's frequently argued that subsidized (or free) condoms have an upside and a downside. The upside is that they reduce the risk from a given encounter, and the alleged downside is that they encourage more encounters. But that's not an upside and a downside - it's two upsides. Without the subsidies, people don't use enough condoms, and without the subsidies, the sort of people who most value condoms don't have enough sex partners.

The main drawback to subsidizing condoms is that they're not very expensive to begin with. You can reduce the price of a condom from a dollar all the way down to zero without having much impact on people's sexual choices.

Our goal, then, should be to drive the price of condoms below zero, by rewarding people who use them. In other words, we should pay a bounty for used condoms. The best of all possible bounties would be one that is more valuable to abstemious Martins than to promiscuous Maxwells. With that in mind, the journalist Oliver Morton has made the marvelous suggestion that if at least some abstemiousness is due to shyness and the inability to find partners (while the promiscuous have relatively little trouble in this regard), then the answer might be to establish a government-funded dating service: bring us a used condom and we'll get you a date.

The entire problem - along with the entire case for subsidies - would vanish if our sexual pasts could somehow be made visible, so that future partners could reward past prudence and thereby provide appropriate incentives. Perhaps technology can ultimately make that solution feasible. (I imagine the pornography of the future: "Her skirt slid to the floor and his gaze came to rest on her thigh, where the imbedded monitor read 'This site has been accessed 314 times.'")

Or, as one of my Slate readers suggested, we could have an online service to record negative HIV test results. You'd type in your prospective partner's name and get a response like "Last negative test result 7/4/2006." Or, to protect privacy, you'd type in not a name but an ID number provided by the partner. Your screen could show both a test result and a photo to avoid fake IDs. This strikes me as such a good idea that I can't figure out why nobody's doing it yet. Until then, the best we can probably do is to make condoms inexpensive - and get ride of those subway ads.

Addendum

In 1996, Slate magazine published an abbreviated version of this chapter that generated hundreds of email responses. Quite a few of those responses were both thoughtful and interesting, and helped me to improve the presentation you've just read. Others contained nothing but a line or two of invective. To those, I usually responded with a short note that read "I'm sorry, but from the email you sent me I was not able to ascertain at exactly which point you stopped following the argument. If you can be more precise about where you got lost, I'll do my best to make it clearer." In a remarkable number of cases, I got responses that were both thoughtful and apologetic, and a few of those led to multiround correspondences that taught me something.

Other readers seemed bound and determined to miss the point by miles. One, brandishing his credentials as a medical doctor, termed the column "particularly unfortunate" and - in a letter that was published in a subsequent issue of Slate - explained why:

We are at a stage in the HIV epidemic in which heterosexual spread is becoming increasingly significant. Casual readers . . . may justify increasing their sexual-risk-taking behavior. Unfortunately, failure, lasting in a shortened lifetime, can result from a sexually successful one-night stand. For an appropriate sequel, the editor of Slate might solicit an article . . . defending Russian roulette as statistically OK but cautioning that three loaded chambers is too risky.