For instance, is Haiti, with an annual population growth rate of 1.3 percent, overpopulated? If it is, then was the United States overpopulated in 1790, when the new country was growing at more than 3 percent per year? And if population density is the correct yardstick, then Monaco, with more than 16,000 people per square kilometer, has a far greater problem than, say, Bangladesh and its 1,000 people per square kilometer.
Back in the 1970s, some scholars tried to estimate the “optimum population” for particular countries, but most gave up. There were too many uncertainties (how much food would the world produce with future technologies?) and too many value judgments (how much parkland is ideal?).
Even considering resource scarcity isn’t all that helpful. During the 20th century’s population explosion — when we went from 1.6 billion people to more than 6 billion — real prices for rice, corn and wheat fell radically, and despite recent spikes, real prices for food are lower than 100 years ago. Prices, of course, are meant to reflect scarcity; by such reasoning, the world would be less overpopulated today than a century ago, not more.
2 Rapid population growth keeps poor countries poor.
In 1960, South Korea and Taiwan were poor countries with fast-growing populations. Over the two decades that followed, South Korea’s population surged by about 50 percent, and Taiwan’s by about 65 percent. Yet, income increased in both places, too: Between 1960 and 1980, per capita economic growth averaged 6.2 percent in South Korea and 7 percent in Taiwan.
Clearly, rapid population growth did not preclude an economic boom in those two Asian “tigers” — and their experience underscores that of the world as a whole. Between 1900 and 2000, as the planet’s population was exploding, per capita income grew faster than ever before, rising nearly fivefold, by the reckoning of economic historian Angus Maddison
. And for much of the last century, the countries with faster economic growth tended to be the ones where population was growing most rapidly, too.
Today, the fastest population growth is found in so-called failed states, where poverty is worst. But it’s not clear that population growth is their central problem: With physical security, better policies and greater investments in health and education, there is no reason that fragile states could not enjoy sustained improvements in income.
3 For all its ethical problems, China’s one-child policy boosts its economy.
China’s economic boom has coincided with the promulgation of its one-child policy, which has used state muscle in an effort to limit births. Both this restrictive policy and the Chinese tilt toward pro-market reforms began in the late 1970s, and since then China’s per capita income has risen more than eightfold. But that doesn’t mean the two are linked.