Thomas Robert Malthus has had a very long run. Issuing his first essay on population in 1798, he has persuaded millions of people that the world is threatened by overpopulation.
“The effect of Malthusianism was immediate and dramatic,” writes historian Gertrude Himmelfarb. “For half a century social attitudes and policies were decisively shaped by the new turn of thought.”[1] And the impact continues.
Until November I had never read Malthus’s essay.[2] To my surprise, it is a delightful essay—-clearly written, easy to read, a relatively short book. (Subsequent editions were more ponderous, I understand.)
Malthus is thoughtful and civil—deferential toward Adam Smith in spite of a disagreement and polite toward the two men whose arguments he demolished, William Godwin and Nicolas de Condorcet. The essay is full of plain-spoken metaphors (using examples such as watches and telescopes)[3] and full of common sense.
The strange thing is this: Not only was his claim about population vs. food production wrong, as we now know from 120 years of experience, his argument for it was just armchair theorizing.
Malthus wrote:
Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison with the second.[4]
For those who didn’t have that acquaintance, he spells it out further. Population would grow this way: 1, 2, 4, 8, 16, 32, 64, etc. Subsistence would grow this way: 1, 2, 3, 4, 5, 6, 7. Eventually, population would exceed food production by a ratio of 512 to 10.
Geometrical vs. arithmetical. This is a marvelously succinct and vivid way of arousing concern about overpopulation. But it’s marketing, not science.
Where did his specific numbers come from? Mostly, he made them up.
On population growth, Malthus starts with one supposedly firm figure—information that the population of the United States doubles every 25 years. Since the United States has more freedom and more food and thus allows population to grow more than elsewhere, “we will take this as our rule,” he says: If unchecked, population will double every 25 years.[5]
As for food production, “the very utmost that we can conceive, is, that the increase in the second twenty-five years might equal the present produce. . . . The most enthusiastic speculator cannot suppose a greater increase than this.”[6] In other words, no one in his or her right mind could imagine food production multiplying like population. At best, it will grow by the same amount every 25 years. Case closed.
So, he applies his ratios to a hypothetical island with 7 million people (about the population of Great Britain at the time). After 100 years the island would have 112 million people. But food production, even assuming it was adequate at the beginning, could only support 35 million people. Seventy-seven million people would go hungry.
Obviously, what Malthus describes would be such a disaster that long before the 100 years were over, the population would have been reduced by famine, disease, or immigration. (By the way, today the island of Great Britain—England, Scotland, and Wales— has about 66 million people.)
I know that there is much to be said in favor of Malthus’s theorizing. Part of his goal was to avoid “positive” checks like famine by encouraging “preventive checks” like late marriage.
But his argument was based on numbers plucked out of thin air. Don’t take just my word for it. As historian J. R. Poynter has written, Malthus “gave a misleadingly precise form to a thesis which did not need to be precise at all, the thesis that even a moderate estimate of the power of increase of human population was greater than even an optimistic estimate of the possible increase in subsistence.”[7]
And, fortunately, his thesis proved wrong in any case.
[1] Gertrude Himmelfarb, The Idea of Poverty (New York: Alfred A. Knopf, 1984),
[2] Thomas Robert Malthus, First Essay on Population 1798. Reprints of Economic Classics. (New York: Augustus M. Kelly, 1965).
[3] Malthus, 234.
[4] Malthus, 14.
[5] Malthus, 21.
[6] Malthus, 22.
[7] J.R. Poynter, Society and Pauperism: English Ideas on Poor Relief. (London: Routledge and Kegan Paul, 1969), 148.