I hope you guys are taking what mcpon says on this subject with a huge grain of salt because that's a massive oversimplification and for the most part not correct, plus there are far more benefits to monogamous behavior than just social ones.
If it works then explain to me the ever increasing divorce rate. https://en.wikipedia.org/wiki/Divorce_demography (UK has 42% divorce-marriage ratio) Clearly the current social construct is becoming obsolete.
I think that both monogamy and polygamy should be not stigmatized, expanding the realm of liberalism.
