We live in an age of all-pervasive cultural pessimism. In one sense, this is understandable. The 18th century, the Age of Enlightenment, produced an explosion of scientific discovery as men’s minds escaped from the shackles of subservience to authority, both political and ecclesiastical. The 19th century was the great age of optimism, as technological development exploited the achievements of science, bringing inventions like the locomotive, the electric light and the telephone.

That optimism dissipated in the 20th century,...