Is Pessimism Rational?

Here's a letter to the Washington Post:

Reviewing Matt Ridley's book The Rational Optimist, Wray Herbert isn't convinced that Mr. Ridley's optimism about both the likelihood and the benefits of continued economic growth is justified ("Matt Ridley's 'The Rational Optimist,'" July 18).

I pose today to Mr. Herbert the same question that Thomas Babington Macaulay posed in 1830 to the irrational pessimist Robert Southey – a question that Mr. Ridley wisely quotes as the introduction to Chapter 1 of...