Today, when my wife and I argue about who should do the dishes, we start from positions of roughly equal strength. If polygamy were legal, my wife could hint that she's thought about leaving me to many Alan and Cindy down the block—and I might end up with dishpan hands.
. . . Antipolygamy laws are a textbook example of the theory of cartels. Producers, initially competitive, gather together in a conspiracy against the public or, more specifically, against their customers. They agree that each firm will restrict its output in an attempt to keep prices high. But a high price invites cheating, in the sense that each firm seeks to expand its own output beyond what is allowable under the agreement. Eventually, the cartel crumbles unless it is enforced by legal sanctions, and even then violations are legion.
That story, told in every economics textbook, is also the story of male producers in the romance industry. Initially fiercely competitive, they gather together in a conspiracy against their "customers"—the women to whom they offer their hands in marriage. The conspiracy consists of an agreement under which each man restricts his romantic endeavors in an attempt to increase the bargaining position of men in general. But the improved position of men invites cheating, in the sense that each man tries to court more women than allowed under the agreement. The cartel survives only because it is enforced by legal sanctions, and even so violations are legion.
（转摘自Steven Pinker：How The Mind Works）