Argument: Polygamy subjects children to an environment of rivalry and insecurity
Rabbi Shmuley Boteach. "The Case Against Polygamy". The Huffington Post. April 23, 2008 - "There is good reason to outlaw polygamy. Marriage is the most romantic institution because it establishes the inviolate uniqueness of its participants. A woman is made to feel that she is the one and only to her husband. A husband's devotion confers upon his wife the blessings of primacy and exclusivity. But polygamy subverts that pledge, establishing not a woman's uniqueness, but her ordinariness. Her husband marries her with the express understanding that she alone will not satisfy him. He requires others. She is inadequate.
Likewise, she is forced now to compete for his affections for the rest of her life, thereby immersing in her an unnatural competition for the man who ahs already pledged himself to her. This competition also erodes the natural fraternity and universal sisterhood of women, engaged as they are, even after marriage, for the affections of the same man.
In this sense, polygamy fosters unending rivalry and leads not to peace and harmony but to altercation and strife. How can any polygamous marriage be happy when, by its very nature, it does not bring people together but drives them apart.
Marriage is the very foundation of every civilized society precisely because of its civilizing influences. Marriage takes a man and a woman who are strangers to each other, orchestrates them together into inseparable flesh, and lends children a stable and secure environment within which to be raised.
Polygamy, however, offers children a model not of security but of rivalry, not of confidence but of permanent insecurity, as the members of a single household compete to be favorites. It is a toxic environment in which men are kings and women are courtiers."