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The Psychology of Denying Overpopulation

Easy math meets bad behavioral economics.

Let’s imagine we were giving an award for the worst social problem in the world today. Do you have any nominations?

International conflict? Racial prejudice? Environmental destruction? Millions of homeless refugees? Exploitation of women? There's one problem that connects all of those, but politicians are often silent about it.

Overpopulation may not be the root of all evil, but it is indeed at the root of many of the world’s other miseries.

Just do the math. As a minimum, every additional person needs a certain quantity of food to eat and clean water to drink. Extra people could, in theory, live without roofs over their heads, but no one wishes for a world with more homeless people. Beyond basic needs for food, water, and shelter, more people need more energy—to light their homes and cook their food, and when that is achieved—to power their refrigerators and washing machines. At higher levels of economic development, people desire cell phones, big screen televisions, and automobiles. At the highest levels, they want second homes and vacations in far-away destinations, reached by flying on gas-guzzling airplanes.

More people means more competition for food and clean water, more demand for places to build homes, and more energy consumed. You don’t need a fancy mathematical model, just the ability to add two and two (or two billion and two billion, still second grade math).

The predictable result of all those extra people satisfying all their increasing energy needs is water and air pollution, garbage floating in the oceans, forests being cut down, longer and longer traffic jams, and increasing urban sprawl. Easy math there, too.

You need to do a little multiplication to understand how the different consequences of overpopulation magnify one another. In a recent blog, I noted how Thomas Homer-Dixon and a team of eminent political scientists linked overpopulation and its consequent resource depletion to intergroup conflict—which follows as people migrate out of blighted areas like Bangladesh into other overpopulated areas, like India, where migrants are unwanted. Homer-Dixon made the case in Scientific American in 1992, when the world population was just over 5 billion. It's now around 7.5 billion and, perhaps predictably, there are now 150 million homeless people in the world, and an estimated 1.5 billion more (that’s billion) living in “inadequate shelter.” The equation works against people living in countries with the least resources, which are growing at faster rates, so there’s less to go around but more people needing it.

After I mentioned this topic recently (an open letter to Samantha Power), one reader referred me to the writings of Philip Cafaro, a philosopher at Colorado State who writes about environmental ethics, overpopulation and the preservation of wild nature. I just finished reading Cafaro’s article on “Climate ethics and population policy,” and recently began his book, “How many is too many: The progressive argument for reducing immigration into the United States.”

In the article on climate ethics and population, Cafaro noted that the continuing failure to deal with overpopulation is not solely the fault of traditional religious groups, like the Catholic church (which has actively worked against birth control). Cafaro points out that his fellow progressives often refuse to talk about the problem, and sometimes attack and insult him when he even brings it up.

Why would progressives refuse to talk about the problem of overpopulation? Well, the reader who pointed me to Cafaro’s work also pointed me to an article by George Monbiot in the Guardian, titled “Population panic lets rich people off the hook for the climate crisis they are fuelling.” Monbiot rails at middle class Americans and Brits, such as Jane Goodall, who dare to publicly express concerns about overpopulation. Here is a central part of Monbiot's case:

Malthusianism slides easily into racism. Most of the world’s population growth is happening in the poorest countries, where most people are black or brown. The colonial powers justified their atrocities by fomenting a moral panic about “barbaric”, “degenerate” people “outbreeding” the “superior races”. These claims have been revived today by the far right, who promote conspiracy theories about “white replacement” and “white genocide”. When affluent white people wrongly transfer the blame for their environmental impacts on to the birthrate of much poorer brown and black people, their finger-pointing reinforces these narratives. It is inherently racist.

That helps explain why people like Cafaro might be reluctant to talk about overpopulation. But Cafaro argues that overpopulation denial is ultimately harmful to the very third-world people Monbiat claims to be defending against the nefarious Jane Goodall.

Indeed, ignoring the consequences of overpopulation is the most immoral thing we can do, whether we are good Catholics or ultra-progressive atheists, and whether we are concerned about people in the first or the third world. The world’s poor are the ones experiencing the worst consequences. It is their forests being obliterated most rapidly, their water being dried up or polluted, their children without enough food to eat, their tribes being driven from their homes by other local tribes who want the same scarcer and scarcer resources.

One temporary solution is to open our borders, allowing more of the world’s desperate people to come to the United States, England, the Netherlands, and Germany. That is the case Samantha Power made in her painful stories of the desperate people she encountered as a journalist and later as U.N. ambassador, which triggered my earlier open letter. The statistics seem to indicate that most immigrants are not criminals or terrorists, but are, compared to those who grow up in first world countries, actually more eager to work long and hard hours. Cafaro acknowledges the obvious -- opportunities in a first world country are substantially greater than those in the third world. And if you are a rich or middle class American, immigrants bring benefits, such as cheaper labor and better bottom lines on stock dividends (large corporations have used the availability of cheaper immigrant labor to break unions, drastically cut salaries and benefits for employees, and produce more net profits for investors).

But Cafaro notes that the benefits to middle and upper-class Americans translate into severe costs for poorer Americans. Middle-class people are generally out of touch with how those economic benefits to them translate into the hefty costs associated with unemployment or underemployment among African-Americans, poor whites, and native Hispanics. Many of these less fortunate groups have lost the union jobs that permitted their parents to live comfortable lives. This in turn leads to loss of health care benefits, and many other unpleasant downstream consequences.

There are other costs to overpopulation, both within and outside the boundaries of first world countries. The destruction of natural habitats to increase farmland and suburbs, combined with overfishing the oceans, has led to the extinction or near extinction of many other species, and diminished the pleasures of finding a quiet natural place to walk and listen to the birds.

To the argument that it is immoral to encourage other people to reduce their family size, Cafaro counters that it is immoral to close our eyes to the environmental destruction, starvation, and future wars that follow from ignoring overpopulation.

Policies to reduce population size don’t need to be coercive. Indeed, Cafaro points to data suggesting millions of people in poorer countries who would be happy to control their family sizes if given access to free or low-cost birth control. Making abortion legal and safe would also help. Some people have reasonable objections to abortion, but if those objections are also accompanied by an opposition to birth control, which could reduce abortions, that is harder to justify given current world population and all the attendant problems of scarcity and desperation facing many children born into the third world. A third solution should be noncontroversial: support education for women, because women who stay in school have fewer children, and those children of educated moms live better lives.

Cafaro also points out that having one less child does more for the environment than all of the other pro-environmental choices you could make: buying a hybrid car, putting in solar panels, improving your insulation, driving and flying less are things we should all consider, of course, but they don’t add up to nearly the same benefits as a little bit of family planning.

There is another obstacle that stems not from religious fundamentalism or misguided political correctness, and I’ve heard it from some of my most educated friends. An ever-increasing population means an ever-increasing market for goods, and is better for “the economy.” But this is using a short-sighted definition of economic utility, which considers dollar signs in the immediate future but ignores the unequal distribution of those dollars into some people’s accounts but not others. The economic utility argument has multiple flaws if we see utility in a world in which fewer people are desperate and miserable, more people live comfortable lives, and more of us get to enjoy the best things in life (that should be free, like a nearby forest or stream).

Back to the math, there is a point at which cramming the world with more people to generate more profits simply can’t go on. That point may already be upon us, and the question is whether we can use our knowledge of human psychology and behavioral economics to rebalance the equation. At the least, we could devote more intellectual and economic resources to getting people to stop denying the problem.


Cafaro, P. (2012). Climate ethics and population policy. Wiley Interdisciplinary Reviews: Climate Change, 3(1), 45-61.

Cafaro, P. (2015). How many is too many? The progressive argument for reducing immigration into the United States. University of Chicago Press.

Homer-Dixon, T. F., Boutwell, J. H., & Rathjens, G. W. (1993). Environmental change and violent conflict. Scientific American, 268(2), 38-45.