Malthus’s Classic “Essay on Population” Revisited

A RETRO REVIEW

“An Essay on the Principle of Population,” by T. R. Malthus; originally published in 1798; Oxford World Classics edition, © 1993, revised edition 2004; 172 pgs., $9.95
By David L. Brown

Anyone who is the least bit clued in about population and environmental issues has heard of Thomas Malthus, the English cleric who published his “Essay on the Principle of Population” in 1798. We all know — or at least we think we know — that Malthus was a doomsayer who predicted that the human race would continue to multiply until the Earth was overwhelmed and destroyed by the press of human numbers. For generations Malthus has been ridiculed for his (supposed) ideas.

Until recently, it had not occurred to me that I didn’t know anyone who had actually read Malthus, nor had I seen any in-depth discussion of his work. I recently saw a book passage describing Malthus as “an English monk,” which I knew was wrong and which seemed to reflect a great deal of ignorance on the part of the writer. My curiosity aroused, I determined to find out what this supposed doomsday character actually said. Going to my nearest bookstore (Amazon.com, located about two keystrokes from my desk), I ordered a copy of Malthus’s book. (Yes, book, for we have been misled by the word “essay” in the title and in fact this is actually a small volume of more than 150 pages.) Reading it and the biographical information it contained was a revelation in more ways than one.

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Editor’s Note: The date of birth on this artwork is incorrect; Malthus was born in Surrey, England, on February 13, 1766.

First, I learned that Malthus was more than just an ordinary country parson (much less a monk). He was a scholar of some note, having graduated with honors in mathematics from Cambridge University in 1788 and completing an MA degree in 1791. He was elected a Fellow of Jesus College, Cambridge, in 1793. He was indeed an Anglican parson in his early years and at the time he wrote his famous essay. However, he went on to become one of the most influential economists of his era. In 1805 he was appointed Professor of History and Political Economy at East India College, a position he held until his death in 1834.

Malthus was well traveled, including an extended trip to Scandinavia and Russia in 1799 and visits to Switzerland and France in 1802. He was a founding member of the Political Economy Club (London, 1821) and was elected a member of the Royal Society. He published many books and articles on economics and was recognized as one of the leading thinkers of his generation.

Malthus left many marks on his age. It was to his work that Thomas Carlyle referred when he dubbed Economics as “the dismal science,” and his friendship with David Ricardo yielded what has been called “the most notable correspondence in the history of economics.” His work also had a significant impact by inspiring the work of Charles Darwin, as reflected in this excerpt from Darwin’s autobiography:

In October, 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for which everywhere goes on … it at once struck me that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of a new species. Here, then, I had at last got a theory by which to work.

So, we have learned that Malthus was far more than just a simple country parson, a characterization that I suspect has been put forth as a way of marginalizing his ideas. But now, what exactly did he say about population? The answer is surprising as well, and while I do not have the time or space in which to address his theories in detail, I will attempt to summarize the broad general outlines.

Initially, Malthus recognized the mathematical fact that human population and the means of support increase by different means, the first geometrically and the latter only arithmetically. He set down his postulates thus:

  • First, that food is necessary to the existence of Man.
  • Secondly, that the passion between the sexes is necessary, and will remain nearly in its present state.

From this he derived that “the power of population is indefinitely greater than the power in the earth to produce subsistence for man.” He continued:

Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will show the immensity of the first power in comparison of the second.

By that law of our nature which makes food necessary to the life of man, the effects of these two unequal powers must be kept equal.

From this it is clear that Malthus believed that there was a balance between population numbers and what the environment can support. To illustrate this, he used a thought experiment based on the assumption that the population of the world, which was about one billion at that time, were to double each 25 years (as had been observed in the recently independent colonies that were now the United States) and that food production would also increase at its own natural rate at 25 year increments. Noting that arithmetical increases in food would follow the series 1, 2, 3, 4, 5, 6… while geometrical increases in population would follow the series 1, 2, 4, 8, 16, 32…, he concluded:

In two centuries and a quarter, the population would be to the means of subsistence as 512 to 10; in three centuries as 4096 to 13; and in two thousand years the difference would be almost incalculable, even though the produce in that time would have increased to an immense extent.

So there is Malthus’s “doomsday scenario,” and yet it was presented only as a thought experiment for the purpose of demonstrating the impossibility of such an event!

In fact, Malthus devotes several chapters to showing how he believes population and the food supply are kept in balance. To briefly summarize, he postulated two kinds of natural force acting to control population:

First a positive one that he labeled “misery,” including hunger, disease and war, which acted to increase death rates;

And second a preventative force, which he termed “vice,” in which he included abortion, birth control, and prostitution, all of which tended to hold down the birth rates.

To add dimension to this brief outline, here is a pertinent passage from the Essay:

Through the animal and vegetable kingdoms, nature has scattered the seeds of life abroad with the most profuse and liberal hand. She has been comparatively sparing in the room and nourishment necessary to rear them. The germs of existence contained in this spot of earth, with ample food and ample room to expand in, would fill millions of worlds in the course of a few thousand years. Necessity, that imperious all pervading law of nature, restrains them within the prescribed bounds. The race of plants and the race of animals shrink under this great restrictive law. And the race of man cannot, by any efforts of reason, escape from it. Among plants and animals its effects are waste of seed, sickness and premature death. Among mankind, misery and vice.

As an aside: in an expanded second edition of the work (and there were several editions issued during his lifetime; it is the original edition of 1798 that I am reviewing here), Malthus introduced a third kind of force that he called “moral restraint” and in which he included postponement of marriage until couples could support a family, and strict celibacy until that time.

Remembering that Malthus was at heart an economist, the Essay on Population is essentially an economic treatise. He devotes several chapters to the economic limits to population growth, i.e., that when there is a surplus of labor wages will decline, and that when there is a shortage of produce, prices will rise. Thus the poor will bear the brunt of population pressure, being caught in a bind of “misery” when squeezed between low earnings and rising costs of living. Malthus opposed financial assistance to the poor on the grounds that it encouraged early marriage and child bearing by those who could not support their families, thus tending to “create the poor which they maintain.” His thinking had a profound impact on the English Poor Laws, which in 1834 were revised to require workhouse service by those receiving assistance.

Standing back now more than two centuries after Malthus wrote his Essay on Population, we can put his theory into a perspective that he himself could not have foreseen, and that is the fact that while he has been unjustly branded as a doomsayer, the very population catastrophe that he thought could not happen may actually be taking place today.

In his time there were scarcely one billion people on the planet, and there were vast tracts of undeveloped land in the New World to absorb more people. Add to that Malthus’s conviction that the natural effects of misery and vice would work to maintain a balance between population and food and one can understand that it would have been difficult or impossible to conceive of the world as we know it. Today the Earth is groaning under the weight of more than 6.5 billion people and there is virtually no available land to support migration. Not only that, but the impact of humanity is degrading and reducing the planet’s ability to produce food — a possibility that Malthus did foresee when he described in his thought experiment how conversion of grazing lands to cultivation of grain would result in the loss of fertility.

It is interesting to compare Malthus’s ideas with modern day warnings of the dangers of over-population such as raised by the environmental scientist Paul Ehrlich in his book “The Population Bomb” (see my Retro Review “Revisiting a Classic: Ehrlich’s “Population Bomb,” posted here on July 15, 2006). Though Malthus and Ehrlich are often painted with the same brush by those who wish to deny the dangers to our civilization posed by the collision between population and the environment, they actually come from very different points of view.

What Ehrlich and others see is that new understanding of the workings of nature have undermined Malthus’s conviction that misery and vice would work to contain human numbers. How is that possible? It is a result of the ecological phenomenon of “overshoot,” (discussed here in my essay “Overshoot and Collapse: A Model for Our Future?” posted August 6, 2006). Simply stated, overshoot describes the situation when a population of living things exceeds the numbers which its environment can support. If there is no way for the excess numbers to move to new sources of food (the classic example is a herd of reindeer on an isolated island), the eventual result of overshoot is collapse, the catastrophic death of many or even all members of the population due to the complete exhaustion of the food supply.

And what we have today is a species of animal (human beings) caught in that same situation, except that instead of an isolated island we are contained within the limits of the entire planet Earth. And, according to most estimates, humans have already overshot the ability of nature to support us, and are rapidly running down the remaining resources to sustain continued population growth. In fact, there is reason to believe that in its original state the Earth could have sustainably supported no more than about two billion humans. (For more on this, read my article “Humanity’s Heavy Footprint on Mother Earth,” posted October 23, 2006.)

So we have learned something together. First that Malthus was no dimwitted country bumpkin acting in the role of Chicken Little with his “the sky is falling” message. Second, we have learned that Malthus did not predict that overpopulation would destroy civilization, but only used that scenario as a way of demonstrating the impossibility of such a thing actually taking place. And third, ironically we have seen that it is quite possibly true that Malthus, in being unable to take into account the idea of overshoot and collapse, could have unknowingly touched on the real future in his thought experiment. Unfairly criticized for being a doomsayer, he may actually have hit the nail on the head.

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