More Sex is Safer Sex

The eco­nom­ic case for promiscuity

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 sex­u­al conservatism.

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

Sup­pose you walk into a bar and find four poten­tial sex part­ners. Two are high­ly promis­cu­ous; the oth­ers ven­ture out only once a year. The promis­cu­ous ones are, of course, more like­ly to be HIV-pos­i­tive. That gives you a 50–50 chance of find­ing a rel­a­tive­ly safe match.

But sup­pose all once-a-year rev­el­ers could be trans­formed into twice-a-year rev­el­ers. Then, on any giv­en night, you’d run into twice as many of them. Those two promis­cu­ous bar patrons would be out­num­bered by four of their more cau­tious rivals. Your odds of a rel­a­tive­ly safe match just went up from 50–50 to four out of six.

That’s why increased activ­i­ty by sex­u­al con­ser­v­a­tives can slow down the rate of infec­tion and reduce the preva­lence of AIDS. In fact, accord­ing to Pro­fes­sor Michael Kre­mer of MIT’s eco­nom­ics depart­ment, 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 cov­ers three-quar­ters of British het­ero­sex­u­als between the ages of 18 and 45. (Much of this col­umn is inspired by Pro­fes­sor Kre­mer’s research.

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 con­di­tions, a few pros­ti­tutes end up ser­vic­ing all the men. Before long, the pros­ti­tutes are infect­ed; they pass the dis­ease to the men; and the men bring it home to their monog­a­mous wives. But if each of those monog­a­mous wives was 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 die out along with it.

Or con­sid­er Joan, who attend­ed a par­ty where she ought to have met the charm­ing and healthy Mar­tin. Unfor­tu­nate­ly Fate, through its agents at the Cen­ters for Dis­ease Con­trol, inter­vened. The morn­ing of the par­ty, Mar­tin ran across 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. Absti­nence can be even dead­lier than monogamy.

If those sub­way ads are more effec­tive against the cau­tious Mar­tins than against the reck­less Maxwells, then they are a threat to the hap­less Joans. This is espe­cial­ly so when they dis­place Calvin Klein ads, which might have put Mar­tin in a more social­ly benef­i­cent mood.

You might object that even if Mar­tin had dal­lied with Joan, he would only have freed Maxwell to prey on anoth­er equal­ly inno­cent vic­tim. To this there are two replies. First, we don’t know that Maxwell would have found anoth­er part­ner: With­out Joan, he might have struck out that night. Sec­ond, reduc­ing the rate of HIV trans­mis­sion is in any event not the only social 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; the flip side of this obser­va­tion is that it is desir­able to max­i­mize the num­ber of (con­sen­su­al) sex­u­al encoun­ters lead­ing up to any giv­en num­ber of infec­tions. Even if Mar­tin had failed to deny Maxwell a con­quest that evening, and thus failed to slow the epi­dem­ic, he could at least have made some­one happy.

To an econ­o­mist, it’s 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 such con­ser­v­a­tives are hard to iden­ti­fy. Insuf­fi­cient­ly reward­ed for relax­ing their stan­dards, they relax their stan­dards insufficiently.

So a social­ly valu­able ser­vice is under-reward­ed and there­fore under-sup­plied. This is a prob­lem we’ve expe­ri­enced before. We face it when­ev­er a pro­duc­er fails to safe­guard the environment.

Extrap­o­lat­ing from their usu­al response to envi­ron­men­tal issues, I assume that lib­er­als will want to attack the prob­lem of exces­sive sex­u­al restraint through coer­cive reg­u­la­tion. As a devo­tee of the price sys­tem, I’d pre­fer to encour­age good behav­ior through an appro­pri­ate sys­tem of subsidies.

The ques­tion is: How do we sub­si­dize Mar­t­in’s sex­u­al awak­en­ing with­out simul­ta­ne­ous­ly sub­si­diz­ing Maxwell’s ongo­ing pre­da­tions? Just pay­ing peo­ple to have sex won’t work–not with Maxwell around to reap the bulk of the rewards. The key is to sub­si­dize some­thing that is used in con­junc­tion with sex and that Mar­tin val­ues more than Maxwell.

Quite plau­si­bly, that some­thing is con­doms. Maxwell knows that he is more like­ly than Mar­tin to be infect­ed already, and hence prob­a­bly val­ues con­doms less than Mar­tin does. 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 under-reward­ed. When you use one, you are pro­tect­ing both your­self and your future part­ners, but you are reward­ed (with a low­er chance of infec­tion) only for pro­tect­ing your­self. Your future part­ners don’t know about your past con­dom use and there­fore can’t reward it with extrav­a­gant courtship. That means you fail to cap­ture the ben­e­fits you’re con­fer­ring, and as a result, con­doms are underused.

It is often 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 down­side is that they encour­age more encoun­ters. But it’s plau­si­ble that in real­i­ty, that’s not an upside and a downside–it’s two upsides. With­out the sub­si­dies, peo­ple don’t use enough con­doms, and the sort of peo­ple who most val­ue con­doms don’t have enough sex partners.

All these problems–along with the 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 envi­sion 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.’ ”) But until then, the best we can do is to make con­doms inexpensive–and get rid of those sub­way ads.

Steven E. Lands­burg, the author of The Arm­chair Econ­o­mist: Eco­nom­ics and Every­day Life, is a pro­fes­sor of eco­nom­ics at the Uni­ver­si­ty of Rochester. His “Every­day Eco­nom­ics” column–applying the lessons of Econ 101 to every­day life–will be a reg­u­lar month­ly fea­ture of SLATE. E‑mail to the author may be sent to

Cur­rent Mood: 🙂amused
Cyn is Rick's wife, Katie's Mom, and Esther & Oliver's Mémé. She's also a professional geek, avid reader, fledgling coder, enthusiastic gamer (TTRPGs), occasional singer, and devoted stitcher.
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