Contemporary sociological research provides extensive empirical evidence justifying the claim that polygamy is disadvantageous for society. [John] Witte cites Rose McDermott’s cross-cultural study of polygamy in 170 countries, which showed,
increased levels of physical and sexual abuse against women, increased rates of maternal mortality, shortened female life expectancy, lower levels of education for girls and boys, lower levels of equality for women, higher levels of discrimination against women, increased rates of female genital mutilation, increased rates of trafficking in women and decreased levels of civil and political liberties for all citizens.
At times, the case against polygamy has been made using arguments, often theological, that would not now hold much sway in the contemporary public square. The case against polygamy begins by considering marriage as a public good. The status of being married is not just about the individual persons and their private relationships; the state publicly recognizes marriage because marriage is a central component of the political common good. Legally recognizing polygamy is a matter entirely different from criminalizing three or more people who live together in a sexual relationship. To recognize polygamy in law is to ask for a governmental stamp of approval of such relationships as “marriages.” We may ask, therefore, whether polygamy is to the advantage or disadvantage of the public good.
Witte’s book is not a systematic political or philosophical treatise against polygamy. It rather provides a useful survey of what has been said over more than 2,000 years of discussion of the issue. The truth is that the good of marriage, and through it the good of future generations, is at stake in how we understand marriage and legally define it