One of history’s more curious encounters occurred in early March 1766 at a country estate in southern England, near Dorking. The estate belonged to Daniel Malthus, a gentleman of independent means and wide intellectual interests. The philosophers David Hume and Jean-Jacques Rousseau were traveling in the neighborhood, seeking a house for Rousseau, who had recently arrived in England under Hume’s patronage after being driven out of Switzerland.

Daniel Malthus was known to both philosophers, at least by correspondence, so they paid him a brief visit, in the course of which they saw his son Thomas, then just three weeks old. So there, presumably in the same room, were Hume, Rousseau, and the infant Thomas Malthus. It was an odd grouping: the serene empiricist, the neurotic social optimist, and the future oracle of demographic doom.

Hume had actually dabbled in demography himself some years earlier. He had been one of the first to argue against the belief, common until his time, that the ancient world had been more populous than the modern world. Demography, along with its cousin discipline of economics, was “in the air” during the later eighteenth century, waiting for the grown-up Malthus to cast his cold eye upon it in his momentous Essay on the Principle of Population (1798).

Of these two cousin disciplines, it is interesting to argue which better deserves to be called “the dismal science.” I would vote for demography. It must be hard to maintain a cheerful composure while scrutinizing