Re (from
Vinccenzo):
"It takes effort to build a healthy relationship with even just one partner. The effort involved in building a healthy relationship with more than one partner can cause instability for all involved."
And the effort involved in building a healthy relationship with one partner can also cause instability for all involved.
The argument assumes that for each added partner, the odds are (greatly) increased that the overall relationship structure will topple. And while everyone has some saturation point (of maximum number of partners they can maintain), the fact is that I know many polycules (my own included) that are doing just fine, including many healthy polycules that are (successfully) raising kids. Admittedly I do also know of some cases where poly wasn't good for anyone in the family, kids or adults, but that's why I say polyamory isn't for everyone.
The thing to consider is whether it's best for children to have the least possible saturation in the adults that raise them; that is, as few partners as possible. But if that were true, then single-parent households would do better than dual-partner households because hey, one less partner = more stability = less chance of things going wrong.
Re:
"How can you have children and put them through the potential unheaval all this might reap? It's not fair to them seeing as they have no power to leave the situation should things get ugly."
No child has power to leave the situation should things get ugly, no matter how (few or) many adults are raising them. My childhood sucked, yet my parents were not only monogamous but also hard-working, God-fearing disciplinarians. From what I've seen, there's just as many crappy monogamous families as there are crappy polyamorous families. In my case, my parents made each other miserable which made them ill-equipped (emotionally) to handle their kids. Everyone would have been happier if they would have divorced (much sooner than they did).
The thing to consider is what the parents are gaining by living polyamorously. If polyamory is increasing the happiness of all the adults, then it stands to reason that they'll be better equipped (emotionally) to handle their kids. Since some adults crave a polyamorous life, it stands to reason that the whole family will benefit if they pursue that life -- provided everyone is consenting of course.