She asked him about the alleged link between forced monogamy and democracy.
That's not a link I'd want to make too strongly [good - he shouldn't], but it has been argued by historians that monogamy precedes, and then seems to go along with, the emergence of democratic ideals. In the Western tradition, the earliest we can trace laws about monogamy is actually to Athens when the first notions of democracy began to be instituted. The argument is that it's meant to create equality among citizens so that, essentially, there'll be wives available to all Athenian men, rather than having all the rich men take many wives. Although, men were still allowed to have slave concubines just so as long as they were non-Athenian women.
He is referring to cultures and times in which women were essentially property. Monogamy kept one man from getting more “property” than another. But with full citizenship for women and gender equality, the dynamics are different.
You can think of it as a first kind of effort to level the playing field. By saying that both the king and the peasant can only have one wife each, it's the first step toward saying that all men were created equal.
But it was literally about men, not women.
The core of the argument is that polygyny -- when men marry multiple wives -- takes up all the women and creates an underclass of men that have no access to partners, and those guys cause trouble. They commit crimes and engage in substance abuse.
It’s a bad argument. See below.
Also, if you have one male with lots of wives, there are all sorts of stepmothers and unrelated adults in the same household as children, and that increases the likelihood of violence.
If everyone was kept isolated from everyone else, then sure, there would be less violence. Violent people are violent wherever they are. The important thing is to avoid violent people, and prosecute them when they assault others. It is ideal for a man who commits domestic violence to have no spouses (or children) with him, not one.
This guy sounds like those people who marry abusers thinking that marrying an abuser and loving them the right way will get them to stop being abusers. Marrying an abusive young man will not stop him from being abusive. It can make it worse.
Back to the “problem” of unmarried men…
Should we force men to get married young so as to avoid that problem?
Here in the US, men (and women) have been marrying for the first time at later and later ages, and guess what? Crime rates are down.
Also, there is a mistake in assuming that the second, third, etc. wives in a polygynous marriage would have wanted one of those unmarried men rather than legally sharing the man they did marry, and that the unmarried men would in turn want to marry them. Some of those men may want to marry men, or not marry at all. Why not allow people to marry the person or people of their choice? Why try to force people to settle? Also, the system is not closed. There are billions of people in the world and more and more people are reaching the age and status of eligibility every second.
Married men commit crime, too. Most of the men in prison have been married, were married or had a girlfriend at the time they were convicted.
Poly relationships are not inherently abusive. Abusive people are the cause of abuse, not marriage. There are many monogamous marriages in which someone is abused. We have several examples showing that outlawing consensual behavior correlates to an increase in problems as people try to avoid law enforcement and other authorities. Marriage equality will most certainly reduce abuse, as abuse victims can go to the authorities with much less fear. So the solution isn’t the status quo, it is in making the relationships official, and prosecuting abusers. Victims will be much more forthcoming.
Gender equality and the right to be unmarried or to divorce are necessary components of full marriage equality. Anti-equality people often point to polygyny in certain cultures, past and present, where women do not have equal rights. However, this is not proof that polygyny, much less the larger scope of polygamy, oppresses women. Women would be oppressed in those cultures with or without polygyny. If a woman wants to marry a man who has other wives rather than another man who is unmarried, and the other wives agree, why deny her that choice? If a woman wants to marry two men, or a man and a woman, or two women, she should have that right, too. Some women enjoy polygamy, including polygyny, and they should have the right to consent to the marriage of their choosing.