Wait, so that polygamist ranch raid might have been based on a false police report?

[A Black Falcon]

Right, on that basis they should be shut down and prosecuted to the furthest extent of the law. I guess I wasn't entirely clear before. I was simply arguing that polygamy in itself isn't something I disagree with.

People who enter a relationship with others define for themselves what they believe to be fair, what the relationship consists of, etc. They should be able to practice that without interference from the law. A vast majority of people agree that a relationship should be between only two people, with the responsibilities/roles of each person evenly divided, and will continue to do so. If a woman doesn't mind having the attention from her husband divided between other wives, who are we to say she can't? The same can apply on the inverse, a woman could have multiple husbands if the husbands are okay with it. If they don't like it, they can find someone else.

I really cannot imagine an argument in favor of polygamy.

Most importantly, polygamy in practice virtually always means polygyny (one male, multiple females), not polyandry (one female, multiple males). This makes sense, given the male domination of pretty much all cultures. Polygamy (polygyny) makes that worse.

Should we ignore injustice just because the people being oppressed don't realize that they are being oppressed? Those women in the FLDS don't realize it, because they've been brainwashed from birth. But going in there and stopping that behavior is the right thing to do anyway because, while morals are something that vary between cultures, I'd say that there are things that are pretty clearly unfair, and polygamy is definitely one of them. Forced isolation and brainwashing are more of them, of course. People certainly should be allowed to choose for themselves, but when it's something which is to their own detriment, is inherently unfair, is almost always tied closely to sexism... I don't know if it would be truly possible to make such a relationship fair.

One other question, if you don't accept that, is the issue of how many people are hurt. If the only person hurt is the person doing it, society is likely to let people do things. But once it starts to affect others too in a negative way, society wants to restrict that action. So cigarette smoking is cracked down on, I would say, mostly for the fact that the smoke poisons other people, not because of how it hurts the smokers (though convincing them to stop is a side benefit). Polygamy does cause social problems. The only way it could not is if the gender imbalance was so bad that the loss of women (or in rare cases men) to polygamous relationships wasn't so much so as to affect the possibilities for the rest of the population to marry, because having a large number of people (usually young men) who have no marriage prospects really isn't a good idea.