1. Between two people who are adults
I'm not intrinsically wedded (pardon the pun) to the idea that it has to be only two people, personally. I appreciate there are practical issues with that in terms of the current structure of the law, but I don't see an inherent ethical problem with the idea.
2. In a loving relationship
This is the bit that I'm sort of wavering on. In principle I think that's what marriage is about, but as a civil structure the benefits don't come from how people feel about each other, but from the stabilising capacity of the relationship within society. On the personal level it's about a loving relationship, ideally, but at the societal level it's about stability: that's why I find it so strange that the gay-marriage equality opponents seem to have gone quiet on divorce, which seems to me to be a much bigger threat to the social benefit of marriage than opening to other people does.
3. Who declare their commitment to each other in a public and legal manner
Depends what you mean by 'public' I guess. It needs to be witnessed by someone independent for the legal niceties, but beyond that...
4. With the intention that that commitment will be for life and excluding all others
Why? Why for life? We know that we grow as we age, and we don't necessarily grow in the same directions - whilst the idea of fixed-term marriages would impact the romance, I wonder what effect it would have on divorces and the like - would not feeling 'trapped' or like the deal was completed encourage people to work to keep it going, would a 'natural' end-point eliminate any of the often acrimonious displays that happen in a break-up?
And 'excluding all others'... in what sense? Sexually - is it about sex? The home? What it is about each other that encourages people to 'bond' themselves differs from couple to couple, and it's for them to decide what - if anything - they are going to keep separate from everyone else, I think.
O.
Isn't that what marriage is all about.
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