Why do economists fail at basic math?

In “Open Borders and the Hive Mind Hypothesis,” economist Nathan Smith writes:

Open borders, in the sense of the abolition of policies restricting migration, would cause billions of people to migrate, and result in almost a doubling of world GDP. Based on a model that stresses human capital as a determinant of the wealth and poverty of nations… two openborders scenarios are constructed. In the first, “pure market clearing” scenario, world GDP rises 91% as 82% of the world’s population migrates, mostly to the West … In the second scenario, with several adjustments made to favor greater realism at the expense of some arbitrariness, world GDP rises 85% as 58% of the world’s population migrates…”

Jesus effin’ Christ. According to Google, there are 7.3 billion people on the planet. About 1 billion of them live in the West/1st world nations. About 6.3 billion of them live in “developing countries.” I’d calculate average population density of the West, but places like Australia (90+% desert) and Russia (Siberia) have big chunks of very difficult to live on land that would render the calculation meaningless. However, it is pretty easy to grok that the population density of Europe and Japan, especially relative to its arable land, is already pretty darn high:

They actually hire people to shove passengers into the trains to make them fit.
Rush hour on the Tokyo Subway


Seriously, where would you even put more people?
Shibuya Station, Japan


There goes the Oxygen
Somewhere near NYC, I believe


Paris has one of the highest poulation densities in Europe.
Parisian apartment complex

So forgive me if I think the idea of cramming 5.17 billion people into the first world actually sounds horrific. Where would you put everyone? How would you feed them? Surely not with crops grown by people on newly freed-up land back in Africa–folks with a TFR of 7 or 8 aren’t going to stop having babies just because they suddenly got the resources to feed more of them. Africa’s population will stay the same.

Even the more modest scenario implies the immigration of 3.65 billion people, resulting in a quadrupling of the West’s current population.

I don’t care what your model shows. This is a recipe for destroying the planet.

Of course, there are factors other than GDP to consider. Like total arable land, crime rates, or having a pleasant community full of people you like and trust–but these are not factors that economists consider valid. We must sacrifice all to the mighty GDP.


Later in the article, he admits that all of his models are based on total assumptions about the way wealth is generated (having dealt with humans, I suspect that assumption is “magic,” but I could be wrong,) and that other models actually show a 25% reduction in global GDP under open borders. This is fine, of course, because someone else might benefit. I mean, not you. You’ll probably starve to death in a smog-ridden hellscape.

For that matter, if you really want to alleviate poverty, you can just give 25% of your income directly to the third world, and then no one has to go through the expense and trauma of moving. I seem to remember a post on Slate Star Codex arguing that it was more effective to just build houses for people in Africa than to ship people to Sweden and then build houses for them there, but now I can’t find it. Maybe it was a different blog? Either way, the point stands: there are probably better ways to raise up the bottom end of society than crashing the whole system.



There’s been talk recently about how Europe (with its negative fertility rates) needs to do more to assist immigrants from countries where women have been having 7 children apiece and are suddenly running out of room. (These countries haven’t had enough food for decades.)

Perhaps I’m missing something, but why should Swedish citizens have their taxes raised to build more housing for non-swedes who chose to come to Sweden? Why should Brits have to send people down to fish boatloads of migrants out of the Mediterranean when their boats collapse? Shouldn’t the people who sent the boats be responsible for the people in them? If I have children, aren’t I responsible for my children? Why does all of this suddenly become Europe’s responsibility?

Ethiopia had 38 million people in 1983, at the beginning of the famine. By the end of the famine, in ’85, they had 41 million people. Today, they have 94 million people. No, they have not simultaneously doubled their ability to feed their people.

Where will those people go? Where will the food come from?

You cannot double the population of Ethiopia without expecting disaster. Yet this is what the Ethiopian people have chosen to do. Who will pay for it? The French?

The usual excuse here for self-destructive behavior is “colonialism.” Ethiopia was never colonized.

Next door, in can-totally-afford-it Somalia, women are having an average of 6 and a half children each. In Nigeria, 7 and a half. The DRC, one of the most dysfunctional, impoverished countries in the world, the kind of place where cannibalism still happens and you can’t even buy Coca Cola,* comes in at a modest 6 children per woman.

*You can buy Coca Cola almost anywhere on the planet except the DRC, because the roads there are just so bad that even capitalism cannot triumph.

Europe is, of course, already massively over-populated. Negative fertility rates are perfectly sensible until Europe, India, China, Japan, and the US populations drop to sustainable levels (unless you really like the idea of living in a post-apocalytic global wasteland.)

The planet cannot handle exponential growth. Even accepting all of the excess people from the places that cannot handle their own current growth levels will not solve the problem in either location. More food will not suddenly appear in Europe anymore than it will suddenly appear in Africa; we will not destroy the planet any slower by shipping people around–this will just speed it up.

We don’t need to stop having children. But we must be sane; countries cannot go having more than 3 per woman. The first step to preventing worldwide famine is birth control. Countries that have not been acting in good faith to not produce more children than they can feed have no basis to ask for international aid or to send out massive numbers of migrants and expect anyone to accept them.

Europe did not create Africa’s overpopulation problem and Europe cannot solve it. At best, Europe might solve Europe’s problems, but I haven’t a ton of hope for that.