The historian Niall Ferguson wishes he could have a free lunch every time he hears "someone declare: 'Malthus was wrong.'" But the converse assertion is equally popular. Throw in some free cocktails every time someone declares that "Malthus was right" and you could be living large for the rest of your natural-born life. (Thanks to Mark Thoma for the link.)

How the World Works' own opinion is that our sample size for determining Malthusian veracity is simply too small. Judged against the history of human civilization, the 200 years or so since the industrial revolution hasn't been long enough to settle whether humanity will survive its own ingenuity. Right now, how you answer the question is more of a personality test than a scientifically provable fact. Glass half-full? We'll figure out a way. Glass half-empty? We're doomed.

Be that as it may, there's a great big goofy hole in Ferguson's dour argument.

Ferguson recapitulates Malthus' basic premise: "'Population, when unchecked, increases in a geometrical ratio,' he observed. but 'subsistence increases only in an arithmetical ratio.'"

Malthus concluded from this inexorable divergence between population and food supply that there must be "a strong and constantly operating check on population."

This would take two forms: "misery" (famines and epidemics) and "vice", by which he meant not only alcohol abuse but also contraception and abortion (he was, after all, an ordained Anglican minister).

Even with the great advances in agricultural yields spawned by the green revolution, argues Ferguson, agricultural yields have indeed only grown linearly. But so too, he suggests, has human population, because Malthusian limits have already been operating.

Meanwhile, vice and misery have been operating just as Malthus foresaw to prevent the human population from exploding geometrically.

On the one hand, contraception and abortion have been employed to reduce family sizes. On the other hand, wars, epidemics, disasters and famines have significantly increased mortality.

Together, vice and misery have ensured that the global population has grown at an arithmetic rather than a geometric rate. Indeed, they've managed to reduce the rate of population growth from 2.2 per cent per annum in the early Sixties to around 1.1 per cent today.

Ferguson has an esteemed reputation as a historian, but if this is an example of his normal intellectual coherency, one wonders on what basis he attained his fame.

Population size has stabilized or is actually declining in most of the economically developed nations of the world -- but to argue that this is due to "vice and misery" requires intellectual sleight-of-hand: defining birth control as "vice." If famine, epidemics or war have been responsible for population declines in Italy or Japan in the last few decades, it's the first I've heard of it. The actual evidence available suggests that people in rich countries have fewer children.

The facts seem pretty clear: Economic affluence checks population growth. And only a disingenuous pessimist could consider that reality to be a dire Malthusian limit.