For the Love of Many
The larger majority of human intimate relationships have involved two people, historically a man and a woman (though times have changed): this man and woman live together, have children together, have sex with each other, and don't turn to other people to fulfill any of those needs. However, it is possible to put together intimate relationships that involve more than two people. These situations are what this article is about.
The practice of having more than one spouse is called polygamy; the condition of having more than one husband or wife actually has its own names ("polyandry" and "polygyny" respectively).
The advantages of polyandry, a woman having multiple husbands, in a sexist world where men work and women stay at home, is that her children receive more care and nutrition; the presence of more than one breadwinner increases the likelihood that the little tots will live to adulthood—an important consideration if, as it was throughout history, child mortality rates are in the 50% area. The advantages of polygyny are... Well, think of it this way: if you could contrive it that your child would be fathered by Brad Pitt, or Albert Einstein, or Johann Sebastian Bach, but to do it you had to become that man's second wife, would you? You probably would: the benefits to your child outweigh the inconvenience to you. Besides, these are rich, successful men who can probably provide for you more healthily than their currently-single competitors. This is the impetus behind animal herds involving one alpha male and a bunch of women: he who is best and most fit (as chosen by natural selection) is the one I want my kids to be fathered by, for the sake of their futures. And finally there's the "group marriage", which is a marriage between three or more people of any combination of sexes and genders. These can get complicated, but in theory bring all the advantages listed above under one (very big) roof.
If you're looking at these ideas and thinking that they're all about straight practicality, well, you're right. The idea of marrying for love—a marriage in which your personal happiness is of prime importance over questions of procreation, economics, etc—is much Newer Than They Think; it's only been standard practice since about the 1600s. Before then, marriages had more to do with child-rearing and political alliances than anything else. And even today, would you seriously marry someone who you thought would make a bad parent? Or, for that matter, who couldn't provide for you if push comes to shove? You probably wouldn't.
The next idea down the list (from most commitment to least) is the idea of polyamory, which is when you are in more than one committed relationship at a time, with the consent of everyone involved. Most people will tell you that, even if you can love more than one person at a time, it's hard to be committed to more than one person at a time, due to the selfish aspects of human nature. Polyamorists disagree. They don't reject commitment, but they do reject exclusivity, jealousy, possessiveness and the negative or limiting emotions that seem to come with it so very often. The main difference between this and polygamy is that marriage is not considered a necessary part of a polyamorous relationship—and nor, for that matter, is sex. Polyamory simply means that you want to form committed lifelong bonds—of any manner—with more than one person. In that sense you could argue that we are all polyamorists: even if we don't plan to have romantic relationships with more than one person, most of us intend to have friends and family around.
You also have swinging, which is the belief that you can be in a committed emotional relationship while still having sex with other people—with, of course, the consent of everyone involved. The root of swinging is the understanding that sex and love are not faces of the same coin, and that one does not have to proceed directly from the other. This is of course patently Truth in Television; regardless of what the "Sex Equals Love" trope would have you believe, it's possible to have sex with someone you don't love, and possible to love someone romantically without having sex with them. People who swing simply maintain this idea into their committed relationships: as long as they have permission from their spouse / significant other / etc and are taking all appropriate precautions, they don't see anything wrong with having some casual sex on the side. Obviously, the spouse gets the same rights and priveleges as you do.
And then finally down at the bottom is the idea of the two-person committed monogamous relationship, which is what Western culture (currently) considers the ideal. In this relationship it's against the rules to do anything sexual or romantic with someone besides your spouse/sig.other/etc. If you break the rules, you're cheating. If you change the rules, then you're not in a monogamous relationship anymore; you belong to one of the poly* categories discussed already.
You'll notice that none of these relationships give you the right to just go out and do whatever (or whomever) you want, without the permission or consent of your partners. Generally, that's reserved for being single. All these relationships involve being committed to somebody—sometimes more than one somebody—and if you get together with someone when your partner(s) has told you not to, then you are cheating and that's that. This is where multi-partner relationships get tricky. Say you're in a relationship with Person A and Person B, and you then want to sleep with Person C on the side. Person A is amenable... But Person B says no, and won't budge. (Maybe Person C was mean to them in high school.) It's hard enough to get permission to do anything from one spouse; imagine having to clear your actions with two! This is one of the arguments people bring up when declaring that multi-partner relationships don't work... and, to be fair, they've got a point. But just because something is difficult doesn't mean it's impossible.
This brings us to one last distinction: an open relationship versus a closed one. A closed relationship is just that: whoever you're with, that person / those people are it for you. It's possible to have a closed polygynous marriage, for instance: say you have three wives, and all three of them have you. If the marriage is closed, then that's it as far as sex, intimacy, etc is concerned: you're not allowed to get any more wives (or sleep with anyone else on the side), and your three wives are likewise limited to you (and maybe each other). In an open relationship, partners are allowed or even encouraged to venture outside their current roster of (sexual / romantic / both) partners. If you're a swinger, that line starts to blur a little: sex can be a lot more casual, although it may still involve deep romantic feelings, or great friendships with various sex partners, and all of it can change for individuals over time, of course. But it's still possible to swing with only a specific set of people ("Okay, hon, we're going to sleep with each other and also with the Joneses, but with nobody else"). Long story short, a "closed" relationship is one that is exclusive[1]. The only question remaining is who you're being exclusive with.
Obviously, there is room for a fair amount of personal discomfort in these things. "I don't believe that these things could actually work," you say to yourself. "I mean, sure, they think it works, and they're certainly trying hard, but it'll never hold together." In the end, all you can do is remind yourself that one man's Fetish is another man's Squick. Yes, there are people out there who think that anything besides a commited two-person relationship is preposterous. Likewise, there are people who would laugh at the idea of monogamy! "We all want variety in our sex lives," they would say. They too have a point. Many poly* relationships lasts years, decades, or lifetimes, whereas Britney Spears had a mono* relationship that blew up in a matter of hours. Who's right? No one can tell you; in the end, it's Something You've Got To Do Yourself. (Most decisions are, when it comes to sex.) Assuming, of course, that you want a romantic or sexual relationship of some sort - some people don't. Find out what if anything works for you, and then don't let anybody tell you it doesn't or can't work. And if they tell you that anyway? Prove them wrong.
- ↑ This article, back when it was written solely by someone who is admittedly mono* , used the word "faithful" here. This word can be offensive to poly* individuals, as the word itself strongly implies cheating, which would be nonconsensual to at least one other partner.