Cafe Hayek: A Letter Inspired by Julian Simon's Insights

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September 21, 2008

A Letter Inspired by Julian Simon's Insights

Don Boudreaux

Here's a letter that I sent this past Summer to the Wall Street Journal:

Ashley Mote is worried because "[d]emographers say the U.K.'s sustainable population is about 30 million - a figure we exceeded over a century ago. Today, we already have over 60 million" (Letters, June 11). Fortunately, the "sustainability" of a population is not chiefly a question of demographics; it's one of economics. It's a question of how effectively the economy encourages people to produce greater quantities of useful outputs from given resources - and how well the economy encourages people to discover hitherto unknown resources.

Consider: A century ago, with a population much closer to the maximum that demographers identify as "sustainable," per capita income in the U.K. was about $4,600 (in 2008 dollars). Today it is nearly eight times higher, at $35,300. So even overlooking the oddity of alleging that population has been "unsustainable" for over a century, the fact that real per-capita income in the U.K. today is vastly higher than it was when population was lower is strong evidence that demographers are bloody way off in their estimate of what population level in the U.K. is "sustainable."