This is something I've been thinking about for a while, and isn't motivated by any particular current events. As much as anything else, I've now got round to writing it up after reading "Ex Machina: Tag", which has a storyline about gay marriage. The basic question is: "what should count as marriage?" Specifically, there are four possibilities.
1. The traditional male/female union that's (theoretically) a lifelong commitment.
2. Gay couples.
4. Fixed term contracts, e.g. "we're going off to university together, so we'll commit to stay together for the next three years, but then we'll reconsider what happens after graduation, in case we want to go our separate ways".
There's some overlap between the last three, but I'll treat them separately here, and then it should follow logically about which combinations work out.
I used to be in the church choir, so I attended many weddings. More recently, I've been along to a few when people I know have been getting married. Anyway, the central part of the ceremony seems to be this:
"Do you take this [man|woman] to be your lawfully wedded [husband|wife], to have and to hold, for richer, for poorer, in sickness and in health, forsaking all others, until death parts you?"
The precise wording may be slightly different, but those are the key concepts that define marriage for me. I remember something that Neil Gaiman said (although it was in a completely different context): "as a writer, whenever a word with a precise meaning loses it, I lose a tool."
That's my concern here - how far can you stretch the definition before you destroy it? E.g. if you wind up saying "We will stay together for as long as we feel like it, and we may get involved with other people too", then in what sense is that a marriage? One solution is to use marriage as a generic term (like "relationship"), and then have new words for the more specific forms of it (e.g. triad). However, I think it makes more sense to keep the existing term for the narrower definition, and then make up a new word for the generic concept (e.g. "shazbot").
So, with that in mind, on with the possibilities.
1. Male/female couples.
This is an easy one - it definitely counts. I'm not saying that this is the ideal state for everyone to aspire to, but if you change the definition to exclude this then you may as well just choose a different word.
2. Gay couples.
There's some dialogue from a "Friends" episode ("The One With The Lesbian Wedding") that's stuck in my mind:
ROSS: I don't get it. They already live together, why do they need to get married?
MONICA: They love each other, and they wanna celebrate that love with the people that are close with them.
ROSS: If you wanna call that a reason.
I think that makes a lot of sense, and I'd say it applies equally to same-sex/mixed-sex couples, so I'm in favour of gay marriage as a concept.
One side-note; it strikes me as odd that the poly community refers to people being "monogamous" or "polyamorous", rather than "monoamorous" or "polygamous" to get the symmetry.
Anyway, this is where things start to get more blurry. My view on poly stuff is that I think it's a perfectly valid lifestyle, but it's not the right path for me. Personally, I'd like to get married one day, so that I can make a lifelong commitment to the [hypothetical] woman I love, where we can promise to stay together and be faithful to each other. I think the same description could apply to a closed group (e.g. if one woman has two husbands), but not when it gets more open-ended (e.g. if those husbands are free to go off and get extra wives in the future). So, I'd count this as "sometimes yes, sometimes no".
4. Fixed term contracts.
This is something I came across in a Star Trek novel a while back, and it's probably shown up in other science fiction stories, but I haven't heard anyone suggesting it in a real world context. I think there are advantages to this scheme, primarily so that it could reduce the divorce rate and also enable people to get out of a relationship that isn't working without having to break their word. However, I don't know whether it's realistic in practice - when I discussed this with a friend, he said that nobody who gets married actually thinks that it's going to fail. So, this would probably have a similar stigma to pre-nuptial legal agreements. As a side note, I'm reluctant to use Pamela Anderson as a role model here, but I think she and her husband had an interesting idea by getting each other's names tattoed on their fingers - the tattoo really is something that you're going to be stuck with for the rest of your life. I'm not sure how effective laser surgery is on this, but it's strange to think that it would be easier to get rid of the marriage.
Anyway, this is another case where I vote "no"; while it may be a valid thing to do, I just think that it's too far away from the central marriage concept.
Having said all that, I think there are some extra issues. Basically, my views here relate to the law, and I'll support any religion's right to impose further restrictions on this. For instance, if a Christian wants to marry an atheist, I have no objection to that, and I think it should be legal, but I'll support any church that says "if you don't believe the words you're saying then you shouldn't be here". I'd also like to separate out some of the legal issues that are currently tied to marriage. Specifically, I think that anyone should be able to nominate a next-of-kin who isn't a relative.
A related question to all of this is whether I support divorce. Whenever I think about this, I remember a line from a Supergirl comic ("It's 'until death do us part', not 'until I get fed up'!"), and I also remember an excerpt from Terry Wogan's autobiography where he basically said "I got married, and we made it work, because we never considered that there was any alternative". On the other hand, I've also seen couples who never should have got married in the first place (particularly when it's wound up with one of them physically abusing the other), and I don't necessarily think it's fair to keep punishing them for that mistake.
As I've written elsewhere, telling the truth is important to me, and so is keeping my word; it comes down to my sense of honour. But I also think about this quote:
"In my experience, the trouble with oaths of the form, death before dishonour, is that eventually, given enough time and abrasion, they separate the world into just two sorts of people: the dead and the foresworn."
(Miles Vorkosigan, "A Civil Campaign", p325)
So, I don't know. I hope that I'll never get divorced, but I'm not going to make any generalisations about whether it's a good or bad thing overall.
Anyway, I'll climb down off my soapbox now. Hopefully I've been able to pull this into a vaguely coherent form; I knew everything that I wanted to say, but it's taken me a couple of hours to do this.