Now, one might think that self-described skeptics and rationalists might be more open to the notion of unconventional relationship arrangements than the population as a whole; at the very least, they're unlikely to fall back on "God said it, I believe it, that settles it" as an argument.
Surprisingly, though, things like polyamory and BDSM sometimes get a great deal of very angry pushback from self-described rationalists and skeptics, who will argue as passionately as any socially conservative or religious person that heterosexual monogamy is the only "right" way to be.
Of course, to be fair, it sometimes works the other way as well; I've encountered at least one person who believes himself to be a rationalist who nevertheless carries on at great and tedious length about how polyamory is the only right way to have a relationship, that all monogamous relationships are coercive and manipulative, and even that monogamy is an invention of Christianity unknown to societies not influenced by Christian teaching...it is often true that self-described "rationalists" seem more skilled at the art of rationalizing than at analytical, critical reasoning. But I digress.
Anyway, I was, for the most part, pleasantly surprised by the JREF thread, which was overall supportive of polyamory. I did make a comment, which in typical Franklin fashion got rather lengthy, addressing some of the specific objections to polyamory that popped up. Most of them pop up in any discussion of polyamory, and seem rooted in social tropes more than they are in religious or social objections to polyamory. My reply:
As a person who's been polyamorous for well over twenty years and also a rationalist, I'm still consistently surprised by the reactions polyamory tends to get from self-identified rationalists.
It seems self-evident to me that the only way one could make a moral case against polyamory is by either looking at systems which offer inequality of opportunity to the folks involved based on sex (eg, systems where men are allowed to have multiple female partners but women are forbidden to have multiple partners) or to invoke some kind of god or gods. Barring that, as long as we're talking about voluntary relationships between consenting adults, no, of course it isn't morally corrupt.
The bits that tend to surprise me, though, are in the assumptions that otherwise rational folks seem to make about polyamory.
Some of these assumptions are deeply woven into our culture, and we're inculcated with them almost from the moment we're born, so I suppose it really shouldn't be surprising that folks do tend to subscribe to them. Tropes like "The only problem is that inevitably people have a desire to be "more" than the other person, have a desire to be the "favorite" and "special"." We're told, from a very young age, that specialness is a unique consequence of exclusion, but it still doesn't make sense to me, and it certainly doesn't match my experience.
I have several partners, many of whom I've been with for a long time (over a decade). All of my partners also have other partners. The fact that they have other partners doesn't make me feel less special; I feel valued by every one of my partners, and I don't need to be in some kind of top-dog position in order to feel valued.
I think that specialness is a slippery concept. It's been my observation that people have two very different approaches to feeling special. One is intrinsic ("I am special because in a world of seven billion people, nobody has or has ever had my exact mix of characteristics, skills, and outlook; when I find partners with whom I am compatible, I value the things about them that make them unique and irreplaceable, and they value the things about me that make me unique and irreplaceable") and one of which is extrinsic ("I am special because someone else tells me I am; exclusivity is what validates my specialness; if that external validation is taken away, I am no longer special"). Folks who need external validation in order to feel special probably aren't as well suited to poly relationships, perhaps.
The idea that plural relationships "tend to be hard to keep together" does not jive with my experience at all. Rather, relationships in general are hard to keep together, if the folks involved lack good relationship skills or aren't compatible with each other; and relationships are easy to keep together if the folks involved have good relationships and are compatible. I would expect it to be far, far more difficult to keep a relationship going with one person who didn't have good communication skills or had a worldview radically different from mine, than to keep five relationships going with folks who were compatible with me!
We do, I think, live in a society that seems to teach us that relationships are something that just kinda happen by random chance rather than something we choose. A lot of relationship problems really do seem to come down to partner selection, but we don't tend to learn good partner selection skills, so we end up with relationships that are hard to keep together because the folks involved aren't really terribly compatible.
What happens when a gay man divorces his bisexual husband who is also married to a bisexual woman with a lesbian wife? Um...that relationship ends? As questions go, this one doesn't seem that difficult to me.
The notion that recognizing a marriage between three people would lead inevitably to recognizing a marriage between 35,000 seems...specious to me. Realistically, I just don't see it happening. For one thing, that number of people is outside our monkeysphere. For another, when we look at buisness networks or open polyamorous networks or other sorts of networked interpersonal relationships, we just don't see them extending that far. I don't see 35,000 people signing a marriage contract "for the lulz."
That aside, I'm not sure what the objection to it would be. So what if there are 15 or 27 people involved? As long as mechanisms exist--which they do, just look at corporate law--to manage ownership and responsibilities and assets and so on, what's the problem? Certainly there are examples through history of children reared in group arrangements, and they seem to work pretty well.
Finally, though the part that baffles me the most are the objections like "people are naturally jealous" or "people are naturally possessive." Yes, people are born with the ability to feel a wide range of emotions--happiness, anger, grief, jealousy, elation, possessiveness, and so on, and so on. Often, these emotions say more about the person than about the environment; for example, it has been my experience that a person who feels jealous doesn't necessarily feel jealous because his partner is with someone else (plenty of monogamous people whose partners are not cheating feel jealous), but because that person is feeling a fear of loss, or an insecurity, or a fear of being replaced, something like that. A partner being with someone else might trigger these things, but that doesn't mean it is the "cause" of jealousy, nor that jealousy is inevitable.
More to the point, people seem to give an almost superstitious level of magical powers to emotions. It is possible to feel angry and to choose not to hit someone or to lash out at someone. It is possible to feel jealous and choose not to act out against that person. Emotions do not dictate actions; we still make choices. And we can make choices that tend to reinforce the things we value (trust, love, altruism) rather than the things we don't (hate, anger, fear).
Emotions aren't in the drivers seat unless we put them there; there's nothing magical or supernatural about them, and we can still make choices even if we are feeling things we don't like.