1- you do realize that marriage laws really only apply once the marriage breaks down.
No, I realize no such thing. Seeing how partners in a marriage have to suppoiert each other, gain rightrs and privlideges the moment they are married I don't see why anyone would claim such a thing? (Oh, and what Darat said.)
So who cares how it would work, how does any marriage work?
By "it" I did not mean the personal relationships between the involved parties but the entire legal framework that exists now and would have to be adopted.
The marital assests get split equally between all parties and custody is decided through mutual agreement or the courts, just like it is with "traditional" marriage.
That assumes that a poly marriage is one entity with several parties, right? It also seems to assume that a divorce would resolve the entire marriage.
There are other possibilites, though, that need to be accounted for. Again, I am not saying it's impossible to do so.
What if in a marriage of 4 people just one of the 4 wants a divorce from 2 of the others, but would be quite happy to stay married to the remaining person, e.g.?
What if there is a marriage between 3 people, and only two of them want to marry a particular fourth person?
2- Nothing changes for any existing marriage. Why would it need to?
Because I was assuming there would be one type of marriage for n people, regardless of wether n would be 2, 3 or 11. I think it is very much possible that changes needed to accomodate 3 or more people would also change how things are handled between just 2 people. (Biological parentage and the required DNA testing being one possible example.)
For me to support poly marriage, i would like ot be shown that there is a proposed framework that simply accomodates these issues.
3- Why does there have to be a benefit to society?
Because there is a cost to society. And because I see no intrinsic right being violated when marriages are restricted to precisely 2 spouses and to precisely one marriage per person at a time.
How would the benefit be any less for poly-marriages than it is for "traditional" marriages? You said you could see the benefit there, explain how the benefit would be different.
I don't know if the benefits would be different. I want to be shown that they wouldn't. (Because, again, I think something is asked that is not a right. If it is a right, I wont ask how it benefits society.)
Society benefits, e.g., if two people agree to support each other in times of need, because society would have to step in less often.
Now, it is entirely possible that it could turn out that there's a net loss here for society under some circumstances. And I think that with marriages of 3 or more people it is possible that the dynamics (on average) are going to be very different.
One-on-one couplings do not change the dynamics of the non-married population, they introduce stability. AFAIK China has problems because more boys than girls are being born (quite artifically). What effects would poly-marriages have in that regard?
It might be a good thing - maybe China should consider it, too ... But: I don't know that it is a good thing, therfore I am not just going to support it.