Yes, you've doubled your income, but you can no longer find any of your stuff. Photographer: David Bazemore/Music Academy of the West via Bloomberg News
Yes, you've doubled your income, but you can no longer find any of your stuff. Photographer: David Bazemore/Music Academy of the West via Bloomberg News

Conservatives are fond of pointing out that if you wait to have kids until you get married, graduate from high school and work full time, you are vanishingly unlikely to be poor. Matthew Yglesias argues that this finding is less exciting than it sounds; it’s basically a combination of arithmetic and the way that the federal poverty line is calculated:

If you look up the Federal Poverty Guidelines you'll see that the way it works is that one person is poor if he or she earns less than $11,490. But due to household economies of scale, the FPG says that for two people to be non-poor they need to make $15,510 not $22,980. Indeed, the poverty line for a family of three is only $19,530 -- less than double the poverty line for one. Basically poverty is $11,490 for the first person plus $4,020 for each additional person.

So imagine a single mom earning the federal minimum wage of $7.25 an hour and working 40 hours a week, 50 weeks a year. She's got $14,500 a year in income which leaves her and her daughter below the poverty line. Now she meets another single mom who's in the exact same financial situation. The two of them fall in love, and since they live in an enlightened state they are able to get married. Now instead of two separate two-person households each earning $14,500 and being poor we have a single four-person household earning $29,000, which is well above the poverty line for four. They could even adopt a fifth child and still not be poor. Which is to say that marriage "lifts" families out of poverty not by increasing their incomes but by reducing what the federal government assumes their expenses to be.

Single people often have roommates for the same reason.

Marriage allows you to pool nonrival goods, such as Netflix accounts, but also what economist Bryan Caplan calls “semi-rival goods,” such as kitchens and cars:

Two childless singles, each earning $50,000 a year, marry. Both keep working, living by the old-school principle of "share and share alike." What happens to their material standard of living? If all depends on how rivalrous their consumption bundle is.

If all their goods are rival (like food), the answer is "Their standard of living stays the same." $50,000 times two divided by two equals $50,000.

If all their goods are non-rival (like Internet access), the answer is "Their standard of living doubles." They pool their money and buy a $100,000 lifestyle for both of them.

In the real world, of course, couples are rarely at either pole Most goods are in fact semi-rival. Consider housing. If you share your home with a spouse, you don't have as much space for yourself as a solitary occupant of the same property. But both of you probably enjoy the benefits of more than half a house. If a couple owns one car, similarly, both have more than half a car. Even food is semi-rival, as the classic "You gonna eat that?" question proves.

But this is not the only benefit of marriage. Marriage also enables specialization. Which can be illustrated by a piece of wisdom I have developed in my brief three and a half years of marital bliss and now pass onto my friends who are getting married: “Marriage makes you stupid.”

I mean, I used to know where I kept my batteries and old documents. But when we got married, my husband, who is much tidier than I am, took over organizing the house. Now, unless it’s a piece of my clothing or kitchen equipment, I have no idea where we keep anything. And while I’m pretty sure I used to be able to put up shelves, now all I know how to do is ask my husband to do it.

On the other hand, he has no idea how much money we have, or in what accounts. And he can’t do the grocery shopping, because he doesn’t know what we consume. Individually, we are less competent to survive on our own. But collectively, we eat better, and we have a tidier house and better-managed finances. And our shelves don’t fall down so often.

Obviously, child-rearing is a major area of specialization. One interesting thing I’ve heard from gay parents is that they find themselves falling into roles that you might describe as “Mom” and “Dad,” even though this is obviously not some pre-programmed gender destiny. It just doesn’t make sense to try to jointly manage a kid 50-50; one parent keeps the social calendar and decides what kids Junior can play with, because two parents trying to do it actually makes the task take a lot more time, as both people have to learn about all the friends and the birthdays and the parents, and then negotiate what Junior does with her time. I’m not saying this happens with every gay parent. I’m just saying that gay parents I know report considerable benefits to specialization.

Specialization also allows for external income gains -- perhaps one reason that married men make a lot more than single ones do and married households are richer than single ones. Some of that is selection effect, of course -- stable, responsible men are probably more likely to get married, especially in this day and age.

So while pooling nonrival and semi-rival goods is an excellent benefit of marriage, it is far from the only one. And it doesn’t stop with economics: There’s also better health, less depression, and happier and healthier children to consider. At the end of his piece, Caplan calls being single a “luxury" good.” But it’s not exactly an aspirational one.