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A Letter Inspired by Julian Simon's Insights

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."

Donald J. Boudreaux