This is kinda where the argument gets muddy. Especially when it starts with "a married person should be able to marry other people, too", because it's adding a person into a marriage without the consent of the other person already in the marriage. If two men are married, and then they both marry two women, who are both already married... did both spouses of the two women have full knowledge of all the links in this chain? Did they give consent to each person in the chain to join it? Are they all spouses to each other? What rights do each end of the chain have towards the other end in terms of property, inheritance, or children?
In principal, I see no reason to restrict marriage to pairs. In practice, it strikes me as incredibly muddy and complex. Joining marriages together seems like a terrible way to do it, but allowing a person to only be in one marriage at once, but not limiting that marriage to two people, strikes me as more reasonable.
Either way, it's an entirely different argument than gay marriage, and the attempts by the anti-SSM crowd to link them got old a long time ago.
I'm a bit of a Heinleiner, and he covers the subject of plural marriages at great length.
He was obviously in favor, and his reasoning centers around the raising of children.
In a nutshell, the benefit is distribution of child rearing duties, as well as interpersonal ones. If a child has six parents instead of two, they are literally three times as likely to get the attention they need at any given time. Same with spouses within the marriage.
Its all contractual, and the complexities of this are examined as well.
Sounds great to me.
The rub is that at this point in time, its not really practical.
I've spent a lot of time on the hippy fringe, and "free love" rarely turns out that way.
But I've seen groups many times FUNCTIONING as an extended family, without the sex. Spreading the burdens around really works, and was the model we used prior to adopting a sedentary lifestyle.
For reference, I've also seen polyamory work. But it takes exeptionally self aware individuals.
"One man one woman" was adopted because the rich and powerful men hogging up all the women, which has been common practise at some point in every culture, didn't end well. Hopeless, horny males get very angry.
I think as we mature as a species, and begin to live longer, plural marriage will become a viable lifestyle choice. But we habe to work out jealousy, possessiveness, ego, etc., first.
