There are circumstances in the imperfect condition we know as human existence when polygyny is morally preferable to its alternative. Individually, such a condition might arise if, early in the marriage, the wife were to contract paralysis or another disability that would prevent sexual union. Collectively, a war that decimated the male population could provide an example, forcing (as this would) the option between polygyny and depriving a large population of women of motherhood and a nuclear family of any sort. Idealists may call for the exercise of heroic continence in such circumstances, but heroism is never a mass option.
On polygyny is Islam. - The World's Religions (1991)