Readers of Matt Ridley’s The Rational Optimist and Ronald Bailey’s columns in the Reason magazine will not be surprised to hear that the rate of population growth is slowing—dramatically—throughout the world. Jeff Wise’s article in the Slate magazine, “About that Overpopulation Problem,” revisits that familiar territory and makes some interesting points. Ultimately, however, Wise fails to appreciate the real reasons for the fall in population growth rate.

First, the good news. As Wise notes, “[The] rate of global population growth has slowed. And it’s expected to keep slowing. Indeed, according to experts’ best estimates, the total population of Earth will stop growing within the lifespan of people alive today. And then it will fall… the long-dreaded resource shortage may turn out not to be a problem at all.”

“For hundreds of thousands of years,” Wise’s article continues, “in order for humanity to survive things like epidemics and wars and famine, birthrates had to be very high. Eventually, thanks to technology, death rates started to fall in Europe and in North America, and the population size soared. In time, though, birthrates fell as well, and the population leveled out.”

Why might that be? “The reason,” Wise avers, “for the implacability of demographic transition can be expressed in one word: education. One of the first things that countries do when they start to develop is educate their young people, including girls. That dramatically improves the size and quality of the workforce. But it also introduces an opportunity cost for having babies.”

True enough, better education is a by-product of development, but where does development come from?

For that we have to look to Ronald Bailey. As he writes, “In 2002, Seth Norton, a business economics professor at Wheaton College in Illinois, published a remarkably interesting study on the inverse relationship between prosperity and fertility. Norton compared fertility rates of over 100 countries with their index rankings for economic freedom and another index for the rule of law. ‘Fertility rate is highest for those countries that have little economic freedom and little respect for the rule of law,’ wrote Norton. ‘The relationship is a powerful one. Fertility rates are more than twice as high in countries with low levels of economic freedom and the rule of law compared to countries with high levels of those measures.’”

And, “Economic freedom and the rule of law produce prosperity which dramatically lowers child mortality which, in turn, reduces the incentive to bear more children. In addition, along with increased prosperity comes more education for women, opening up more productive opportunities for them in the cash economy. This increases the opportunity costs for staying at home to rear children. Educating children to meet the productive challenges of growing economies also becomes more expensive and time consuming.”

So, education is a proximate cause of population growth slowdown. The ultimate cause, however, rests with economic freedom and resulting prosperity.