Bryan Caplan, who has a new book out, speaks in praise of his competition, Steve Landsburg. Landsburg’s new book bears the risqué-yet-Freakonomics-esque title, More Sex is Safer Sex, and its title essay demonstrates the power of model-building in an unusual problem domain:
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 these monogamous wives were willing to take on one extramartial 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.