Pursuit of Truthiness

my gut tells me I know economics

Malthus was right, but he would want you to have kids

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Mr. Malthus- central Propositions correct, indeed obviously so- Misinterpretations by modern critics and supporters- The importance of certain technological developments

Thomas Malthus is famous for his 1798 Essay on the Principle of Population, which argued that population will always quickly rise to the limit that the food supply allows, meaning many people will always live in poverty and near-starvation.  Ever since its publication, people of all kinds have been eager to attack the ideas and their author.  I have to admit I always found it hard to take Malthus seriously- mostly because the last 200 years of increasing population without world famine seem to prove him wrong; also because of the silliness of the “arithmetic vs. geometric growth” thing.  However, when you look closely at what Malthus said, he was mostly correct, and when wrong it was not for the reasons most people came up with.

Malthus’ main ideas can be summarized: 1) people need food to live  2) there is only so much land to grow food on 3) Given that the “passion between the sexes” is a part of human nature, people just keep having kids 4) given 1-3, population will increase until it hits the food-limit imposed by nature and is kept in check by starvation

He notes that when people encounter “new” land, as in America, their population will double as quickly as every 25 years and quickly fill it up; people everywhere would like to have enough kids that population increases in this way.  It is hard to imagine agricultural productivity doubling every 25 years to enable the same population growth on a set amount of land.  Certainly adding more workers to a given farm quickly hits diminishing returns.  Further, it is hard to imagine even now- and must have been very hard in 1798- to imagine that new techniques, crops and machines could double output every 25 years.

Malthus describes many ways in which population is kept in check short of famine.  There are other ways the death rate is increased- war, disease, infanticide- and he argues these become more common when food is short.  There are ways the birth rate is decreased- abstinence and late marriage.  His economic analysis is excellent for its time.  He describes how price signals enable individuals to make decisions that avoid famine.  As population gets close to the food limit, food prices increase, so kids become more expensive to feed, and people try to have fewer of them.  When many people are nearing the subsistence level, the price of labor will be low.  When labor is cheap and food expensive, farmers will have a bigger incentive to produce more food.  Prices enable population to fluctuate less violently around the equilibrium level.

Malthus’ main descriptive proposition, that population will quickly catch up to any increase in potential food production, was true for essentially all human history until about 1880, when the demographic transition began in earnest and children per woman began its long decline while agricultural productivity expanded rapidly.  But what policy conclusions did Malthus draw from his idea?  This is where things get weird.

Malthus’ idea has been adopted by leftist environmentalists to argue that people in general should have fewer kids.  This is probably why I thought Malthus must be wrong when I heard about him as a college freshman.  But Malthus himself didn’t argue this at all.  In fact, Malthus thinks that having kids is great as long as you can afford to feed them with your own money.  He likes kids; he doesn’t like it when they starve; he doesn’t like it when people have to turn to welfare or adoption to get their kids fed.  He really didn’t like welfare:

“The poor-laws of England tend to depress the general condition of the poor…. increase the population without increasing the food for its support…. create the poor which they maintain…. diminishes the shares that would otherwise belong to more industrious and worthy members… dependent poverty ought to be held disgraceful.” p 38-9 Norton 2nd ed

Malthus’ main policy conclusion is that the poor laws (the welfare of his day) should be abolished.  His secondary conclusion is to support agricultural productivity, by encouraging “tillage above grazing” (thus producing more calories per acre), opening new farmland, and encouraging agriculture above manufacturing and cities.  This will increase the number of people the land of England can support.

His main advice to individuals is not to have kids if they are likely to starve or have to go on the public dole.  If welfare is abolished as he would like, this is simplified to: don’t have kids if they are likely to starve.  This is why I feel confident that Malthus wouldn’t mind if you (I assume those likely to read this could afford to feed kids) have kids.

So what did Malthus get wrong?  He didn’t foresee effective birth control or the explosive, endogenous growth of agricultural technology.  He assumed that having fewer kids would always mean misery (abstinence) or vice (infanticide), both of which are hard to do.  If he had known about condoms or the pill, he may have called them “vice”, but he would recognize them to be easier than abstinence and more moral than infanticide.  Birth control, when people are rich and educated enough to use it, is itself enough to evade the Malthusian trap, as below-replacement birthrates in many countries now attest.  Malthus saw technology as something that developed slowly and randomly, so he didn’t consider that it could avoid the trap, and didn’t include research as a way to encourage agriculture.  In fact, agricultural technology has grown “geometrically” (exponentially).  It has not done so randomly, but instead is largely due to factors Malthus ignored- like government-sponsored research- or spurned as pulling workers away from agriculture, such as cities (where most inventions and discoveries take place, even in agriculture) and manufacturing (which makes tractors, et c).

On the whole, though, I was surprised by how rational Malthus’ writing is and how much modern economics he knew in 1798.  His work has not been rendered completely irrelevant by technology and birth control; much of the world does still live on or near the Malthusian frontier.  It is unclear to me whether it is helpful to give food aid to such regions, either through private charity or government food subsidies as with Indian rice.  Personally I think giving to education in poor countries is a better bet, and the fact that it does not aggravate a potential Malthusian trap is one reason why.

To get back to kids though, there are lots of good reasons you may not want them, but one reason you shouldn’t have is that “the world is overpopulated and Thomas Malthus would be sad”.


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Written by James Bailey

June 2, 2011 at 5:23 pm

2 Responses

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  1. […] Pursuit of Truthiness my gut tells me I know economics « Malthus was right, but he would want you to have kids […]

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