I had to read up on Rawls ahead of this, so take it with a grain of salt. My understanding of his original position is that morality is formed as a social contract between social individuals, not as pre-social individuals.

This means that the contract takes into consideration the other people involved in the moral rules. In the case of the 3, it would depend on each of the individuals feelings. Maybe one of the people doesn't want to share their "marriage" with more than one person. In that case, they would not advocate for polygamy. Polygamy would only be the most "rational" if they considered that each of them would not simply tolerate, but actually like having more than one person in the marriage.

This would be in contrast from a "pre-social" individual, who would have their own personal moral code apart from others. Such a person would dictate a moral code that the others had to follow, regardless of the other's feelings on the issue.

So I don't think that polygamy is the most rational justification according to the original position. Feel free to disagree.

The original position view on marriage would be the that any kind of marriage between any number of consenting individuals is permissible. Including polygamy.

And what do you know, polygamy actually is ethically permissible, so it all works out.

Thanks for the feedback. I can’t look up my references right now or be too detailed on my phone, but I think Rawls would not agree that our sexual preferences should be carried into the original condition (in response to Philosphim), just that we are sexual being and that “marriage” is an important institution in a just society.

Nor does it seem like Rawls would be okay with any concept or definition of marriage (in response to Pfhorrest), since he recognizes that family arrangements can have significant effects on things like wealth and social capital. In fact this is part of what gives rise to my thought.

If entering into a marriage provides certain privileges to those within it and whatever children they have or adopt—then Rawls should say that we should only enter into it if doing so is also to the advantage of the least in our society. But it also seems like in the original condition we have an interest not just for “marriage” however it might be defined but for a definition which is most just: which is to everyone’s advantage. But since we don’t know whether every person will have a mate in a monogamous society, just as we don’t know whether every person will be wealthy or intelligent in a meritocracy, then we should choose open, polygamous marriages as the norm.

Nor does it seem like Rawls would be okay with any concept or definition of marriage (in response to Pfhorrest), since he recognizes that family arrangements can have significant effects on things like wealth and social capital. — JohnRB

Are you sure you're not reading your own domestic preference into his position? Very hard for me to see Rawls arguing against polygamy just as long as all parties consented.

Are you sure you're not reading your own domestic preference into his position? Very hard for me to see Rawls arguing against polygamy just as long as all parties consented — JerseyFlight

My response is a bit long, but I think it's worth it to try and make the case as convincingly as I can... in the space of about an hour of my day.

It's possible that I'm over-reading Rawls as you suggest, but here are some references that I think support my reading of Rawls in regard to marriage (potential objections addressed below).

"For us the primary subject of justice is the basic structure of society, or more exactly, the way in which the major social institutions distribute fundamental rights and duties and determine the division of advantages from social cooperation. By major institutions I understand the political constitution and the principal economic and social arrangements. Thus the legal protection of freedom of thought and liberty of conscience, competitive markets, private property in the means of production, and the monogamous family are examples of major social institutions. Taken together as one scheme, the major institutions define men's rights and duties and influence their life prospects, what they can expect to be and how well they can hope to do." — Rawls, A Theory of Justice (rev. ed.), p. 6

"Furthermore, the principle of fair opportunity can be only imperfectly carried out, at least as long as some form of the family exists. The extent to which natural capacities develop and reach fruition is affected by all kinds of social conditions and class attitudes. Even the willingness to make an effort, to try, and so to be deserving in the ordinary sense is itself dependent upon happy family and social circumstances. It is impossible in practice to secure equal chances of achievement and culture for those similarly endowed, and therefore we may want to adopt a principle which recognizes this fact and also mitigates the arbitrary effects of the natural lottery itself." — p. 64

Let me say a few things about each quote. Regarding the first quote, obviously this quote provides the most potential difficulty as the term "monogamous family" would seem to rule out an open, polygamous marriage. Furthermore, one might also question the link between family and the more specific state of marriage.

Answering this second problem first, it seems obvious that by "monogamous family" Rawls simply means "monogamous marriage." My reasons for this are three-fold. First, the idea of a "monogamous family" (as opposed to marriage) is prima facie nonsensical. Second, let's assume that the concept of a "monogamous family" does make sense if we stipulate a certain definition. This seems unlikely since Rawls never stipulates a definition. But whatever unusual sense we stipulate will likely end up being insignificant to the type of privileges that Rawls has in mind and which social scientists typically think result from stable marriages (just do a google search if you aren't familiar with this data). In other words, it would be strange, not to mention implausible, that Rawls thinks certain privileges result from monogamous families-but-not-marriages where this means brothers and sisters who don't have any adopted brothers or sisters or form close bonds with non-blood relatives that might be considered colloquially "blood brothers." And the third reason follows from this and really just further strengthens it, which is that Rawls later speaks positively of the principle of fraternity (I won't take the time to look up the reference here unless someone wants it).

Now regarding the first and more important objection, my answer has to rely more on considerations more external to the text. First, at the time Rawls was writing (even in the revised edition in 99) I don't think there was enough data from the social science on non-monogamous stable marriage. That is, most of the data for comparison with monogamous marriage would have been of relationships that involved one man and one woman who were unmarried. There wouldn't have been a large enough sample size of same-sex marriages or open, polyamorist marriages (there still is not much for the former, is my understanding, and even less for the latter, since polyamory is still illegal in the U.S.). Furthermore, when Rawls was writing (again this is largely true in 99 as well) non-monogamous, non-heterosexual marriages weren't even on most people's radars. (Recall that Clinton signed DOMA into law and Obama only supported civil unions in his first term.) So most likely Rawls isn't trying to say anything about polyamorous or open marriages or even same-sex marriages. Rawls is probably just thinking something like the following: "when people get married and stay married this has certain privileges over against when people don't get married or don't stay married."

But today we have a much more expanded view of which types of long-term relationships and marriages are possible and permissible. This is why, to my knowledge, marriage doesn't feature as a consideration in his original position. It likely just wouldn't have occurred to Rawls for monogamous marriage to feature in the thought experiment since, in his context, of course society has to have marriage and the only alternative is something like hook-ups or divorce. But there's no reason that we shouldn't consider marriage arrangements that weren't on his radar or hardly anyone else's at the time.

Next, turning to the second quote. The last sentence brought to mind that someone might object to my inclusion of marriage arrangements in the original position because those things which Rawls considers in the thought experiment are already meant to address the sorts of inequalities which result from the basic structure of society. In other words, Pfhorrest's objection might turn out to be correct. Since the principles of justice that Rawls arrives at through his thought experiment balance out the inequities of the basic structure, it doesn't matter what sorts of marriage arrangements we do or do not have.

However, I don't think this is a successful objection because Rawls wants (and his representative people want) to arrive at the most just society and not simply a just society. Thus, connecting with my answer to the first objection of the first quote, that Rawls arrived at a theory of justice which doesn't prefer any arrangement of marriage and which he thought would lead to the most just society doesn't mean that we, with a broader landscape for social and relational arrangements, must limit ourselves to Rawls's arrangement. Rawls would have agreed with this himself, since at one point he mentions that we are allowed to take data about what works or doesn't work, say, economically, into account and (I don't remember if he says this explicitly) that must include new data from future generations or experience. (Will look up the source if someone wants it.)

Finally, I'll reiterate that it's possible that my entire project here is naively off-track since there's an obvious principle or thing Rawls says which renders my argument irrelevant or answered. I've gone through the trouble of writing the above simply on the assumption that I'm on the right track.

P.S. And of course as Pfhorrest brings to our attention, if polygamy is not unjust then my further point about challenging the original position is moot. Right now, I'm more interested in whether the more immediate claim goes through.

I think in that first Rawls quote, he is not endorsing all of the things he lists, but simply listing common well-known examples of “major institutions” the likes of which are the things being decided upon from the Original Position. So he’s not saying that monogamy is a necessary thing for justice, but that questions of justice include questions about things like whether or not to allow/require/etc monogamy.

That seems unlikely since elsewhere in the book Rawls specifically endorses each of the other institutions that are listed. Monogamous family would have to be the only thing he tacks on to that list that he sees as irrelevant. Also, given that he thinks it provides privileges, it wouldn't be listed just because he is thinking of things our society happens to have. The fact that he considers it part of the basic structure itself indicates he does not think it is incidental or of no concern, in addition to the second quote.

The fact that he considers it part of the basic structure — JohnRB

I think this is where you are going too far. If it's part of the basic structure, that doesn't necessarily mean Rawls is trying to advocate for it conservatively, it's just part of what you find in our culture. Also, that it provides privileges should not be read as Rawls giving it an exclusive endorsement. He's just making a statement of fact regarding its utility.

Finally, I'll reiterate that it's possible that my entire project here is naively off-track since there's an obvious principle or thing Rawls says which renders my argument irrelevant or answered. I've gone through the trouble of writing the above simply on the assumption that I'm on the right track. — JohnRB

You have my respect. You come to a public forum to test the cogency of your ideas against other critical minds. This is quite intelligent.

Interesting discussion, guys.

Assume that 3 people are in the original position and they are considering how to create a just institution of marriage. None of them know which, if any, are male or female. — JohnRB

So the idea is that the veil of ignorance obliges one to take an approximately neutral position that favours equality in so far as it is compatible with prosperity, stability. and so on. Now in principle, one is ignorant of one's own position, but cognisant of the consequences of whatever options are being considered. And this is problematic in the case of marriage, or I should more properly say in more neutral terms the fundamental organisation of sexual relations, living arrangements and child-rearing.
What one has to call 'experiments' with other ways of living are so few, so diverse, and so pre-soaked in the conventions of family, that I do not think one can make a judgement.

It is a fairly general problem with the theory, that it tends, even with the good-will to all engendered by the veil, to stay with the known arrangements - 'for fear of something worse'. Not many of us have been brought up with free love in a commune, and one tends to have experienced a (monogamous) family for better, or institutional care for worse. So from the limited knowledge one has, I suspect most people (here) would favour something close to voluntary consenting relationships of any number with means of ending them available, and robust protection for minors. Roughly what we decadent Westerners have.

Anyways, just because Rawls invented the original position as a thought experiment, does not prevent us from conducting the experiment on our own knowledge and experience and reaching different conclusions. Those used to tribal living, or from a Kibbutz, might have other ideas...

Taken together as one scheme, — Rawls, A Theory of Justice (rev. ed.), p. 6

Incidentally, I understand this phrase to acknowledge in principle, that there are other possible schemes, that one might choose if one knew of them.

An interesting critique of Western Society from an external view, can be found here and may be instructive. https://www.channel4.com/programmes/meet-the-natives