Thursday 4 July 2013

A simple argument in favour of polygamy

Will Wilkinson and Scott Adams provide nice arguments in favour of legalising polygamy.

Wilkinson draws a rather useful parallel with drug prohibition: existing observations will necessarily be from the fringe and can't be used to extrapolate to a legal environment:
As a former tour-guide at Mormon historic sites, I have encountered more than one fundamentalist Mormon family in which the strutting husband seems to regard his flock of servile wives like glorified property. We're not wrong to want to discourage this. Moreover, those remote compounds in which exile fundamentalist communities brainwash their girls and discard their surplus boys are intolerable horrors. But this is all the more reason to bring polygamy out from the margins of our society. As with sex work, the horrors here have little to do with anything inherent in the practice and almost everything to do with the fact that we've made it illegal and dishonourable. 
I'll make a different argument.

The division of labour is limited by the extent of the market. We've tended to model families as being machines for home production. The family member with a comparative advantage in market labour does more of that for wages while the one with a comparative advantage in home production does more of that; more wages get earned and more home production gets undertaken.

Marriage has been shifting away from complementarity in production towards complementarity in consumption. Read Wolfers & Stephenson on this point. If a couple are both really good at market labour, they'll wind up outsourcing most of the home production. Nannies, maids, laundry services - all of these take the place of home production for high-ability couples.

Now suppose that individuals are heterogeneous both in abilities and in preferences over home production. Some high ability people simply really enjoy spending lots of time with the kids rather than spending lots of time out of the house. Suppose further that there are non-contractable elements in home production that get nicely sorted out via the implicit contracts in marriage. Marriage requires a whole lot of trust. Once you've sunk all the fixed search costs and decided that you trust someone enough to marry them, you can trust them on a lot of margins. Outsourced home production requires a whole new set of trust evaluations. You have to find a cleaner you can trust with your house. A nanny requires far more trust. Within marriage, love sorts out the non-contractable elements and encourages good outcomes. More marriage partners opens up more scope for the division of labour on household and market production: more people who can spend the day at home if a kid's sick, more people who can take turns covering during school holidays, smaller burdens imposed when one partner needs to head off for a conference. And, more opportunities for complementarity in consumption as well.

The law against polygamy isn't a binding constraint for us as I rather doubt we'd seek to expand were the law changed. But I'm not sure why it should be illegal for others to enjoy the advantages.


  1. Interesting post. It's not obvious that in fact there are household production advantages to polygamous relationships. I suspect there are quite a few woman out there who would be more willing to share their husband than their kitchen. If, in fact, polygamous relationships were legal, I suspect by far the most common arrangement would be wife 1 has house 1, wife 2 has house 2, etc, and husband divides his time between the households. (Or the gender roles could be reversed).

    Does a husband have to ask his wife for permission before marrying a second wife? Does he have to tell his first wife before marrying a second? Are the first wife and the second wife married too?

    Polygamous marriage is a whole lot more straightforward than polygamous divorce, though.

    Imagine a polygamous relationship where the husband was a farmer, producing mostly in-kind income, one wife had a steady job and generated most of the family's cash, and the other wife stayed home and looked after the kids.

    If one wife leaves, what obligations does she have to, and what claims does she have on, the other wife or wives? How would the division of assets work?

    Could the wife with a job owe the at-home wife alimony or child support?

    If the husband dies, what claim does each wife have on his assets?

    How is eligibility for refundable tax credits and other low income supports determined? Does one wife have an obligation to share her income with other wives?

  2. Hi Frances,

    If adding an additional marriage partner requires the consent of all of those currently in the marriage partnership (as it should), then I'd expect the first ones to take up such arrangements would be those who were happy to share a kitchen. There are plenty of wives who are happy to share their kitchen with their husbands already. I have a far harder time seeing the point of the whole thing if it's spread across multiple households.

    Doug Allen raised a lot of similar concerns when he visited here last semester (when are you coming, by the way?). I'd expect that, in your scenario, the wife with the job should owe alimony to the one without, but I'd also expect that the marriage contracts would have reasonably explicit exit clauses because there obviously isn't an extensive body of common law on which to draw. I'd also expect that each would be treated as full partners, so each eligible for equal shares of assets if one partner dies.

    I also expect that the most common arrangement would wind up being one woman in China with two or more husbands.

    Refundable tax credits and the like... I'd expect it would have to depend on household income averaged. So if you have 3 adults and 5 kids on x household income, you'd be treated as though there were 2 adults and 10/3 kids on 3/2x household income, then ratcheted up for the actual number of adults/kids. But it would also likely need to be curved because of the household production opportunites afforded by the additional spouse. Big picture though, I'd expect that whatever obligations husbands and wives owe to each other under the law currently would extend to all additional partners inside the relationship.

  3. My undergraduate take on the issue.