Today in Science History - Quickie Quiz
Thomas Robert Malthus
(13 Feb 1766 - 23 Dec 1834)
English economist and demographer who published his theories, an early systematic analysis of human society, in An Essay on the Principle of Population. He quantified the rates of increase of population versus food supply, and the consequences.
Short biography of Thomas Robert Malthus >>
Thomas Robert Malthus
“Population…increases in a geometrical ratio”
Illustrated Quote - Large (800 x 400 px)
— Thomas Robert Malthus
From An Essay on the Principle of Population (1798)
More Thomas Robert Malthus quotes on science >>
When Thomas Malthus first published his famous essay in 1798, the book carried the title An Essay on the Principle of Population: As it Affect the Future Improvement of Society with Remarks On the Speculations of Mr. Godwin, M. Condorcet, and Other Writers. It had nineteen chapters.
Chapter I began with Malthus stating the question he wanted address in his essay. The quote above is found toward the end of the chapter. The quote gives his most well-known point: that a matching increase in necessary food supply will at some point not be able to keep up with continuing population growth.
After stating that as a mathematical certainty, Malthus expands its implications, as follows:
“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 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.
This implies a strong and constantly operating check on population from the difficulty of subsistence. This difficulty must fall somewhere; and must necessarily be severely felt by a large portion of mankind.”
In An Essay on the Principle of Population (1798), 14. (source)
Nature bears long with those who wrong her. She is patient under abuse. But when abuse has gone too far, when the time of reckoning finally comes, she is equally slow to be appeased and to turn away her wrath. (1882) -- Nathaniel Egleston, who was writing then about deforestation, but speaks equally well about the danger of climate change today.
Albert Einstein: I used to wonder how it comes about that the electron is negative. Negative-positivethese are perfectly symmetric in physics. There is no reason whatever to prefer one to the other. Then why is the electron negative? I thought about this for a long time and at last all I could think was It won the fight! ...(more by Einstein)
Richard Feynman: It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly. ...(more by Feynman)
Quotations by: Albert Einstein Isaac Newton Lord Kelvin Charles Darwin Srinivasa Ramanujan Carl Sagan Florence Nightingale Thomas Edison Aristotle Marie Curie Benjamin Franklin Winston Churchill Galileo Galilei Sigmund Freud Robert Bunsen Louis Pasteur Theodore Roosevelt Abraham Lincoln Ronald Reagan Leonardo DaVinci Michio Kaku Karl Popper Johann Goethe Robert Oppenheimer Charles Kettering ... (more people)
Quotations about: Atomic Bomb Biology Chemistry Deforestation Engineering Anatomy Astronomy Bacteria Biochemistry Botany Conservation Dinosaur Environment Fractal Genetics Geology History of Science Invention Jupiter Knowledge Love Mathematics Measurement Medicine Natural Resource Organic Chemistry Physics Physician Quantum Theory Research Science and Art Teacher Technology Universe Volcano Virus Wind Power Women Scientists X-Rays Youth Zoology ... (more topics)
Malthus’s Population Principle Explained
By Frank W. Elwell
This essay is a faithful summary of Malthus’s original 1798 “Principle of Population.” While nothing will substitute for reading the original essay with an open mind, I hope this summary will go some way toward rehabilitating this man’s reputation.
Malthus first points out that human nature being what it is, the passion between the sexes appears to be fairly constant and, if unchecked population will double itself every twenty-five years. "Population, when unchecked, increases at 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 with the second." And this leads to Malthus’s principle of population. Because of this unequal power between production and reproduction, "population must always be kept down to the level of the means of subsistence.” While Malthus was not the first one to notice this, he was the first to inquire into the means by which this leveling of population is achieved. The key word in the principle is “always.” Why then do people insist that Malthus predicts a future of population overshoot and collapse?
Here is the key to that riddle: Malthus made the mistake of illustrating the unequal powers of production and reproduction with a mathematical illustration. He supposes that when unchecked, the earth’s human population would double every twenty-five years (a good estimate consistent with current knowledge). Agricultural production at best, he argues, could not possibly keep pace.
But to make the argument more general and less interrupted by the partial views of emigration, let us take the whole earth, instead of one spot, and suppose that the restraints to population were universally removed. If the subsistence for man that the earth affords was to be increased every twenty-five years by a quantity equal to what the whole world at present produces, this would allow the power of production in the earth to be absolutely unlimited, and its ratio of increase much greater than we can conceive that any possible exertions of mankind could make it. Taking the population of the world at any number, a thousand millions, for instance, the human species would increase in the ratio of—1, 2, 4, 8, 16, 32, 64, 128, 256, 512, etc. and subsistence as—1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. 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, though the produce in that time would have increased to an immense extent (8-9, emphasis added).
He knows full well that population cannot grow long beyond the means of subsistence (“population must always be kept down to the means of subsistence”), he is simply trying to illustrate to his readers the unequal powers of growth in population and food production and therefore the necessity of checks on population. At one point in the Essay he even states: “I am sufficiently aware that the redundant twenty-eight millions, or seventy-seven millions, that I have mentioned, could never have existed” (63). But for various reasons many critics have taken this mental experiment as the theory of population itself and delight in writing that Malthus was wrong, that overshoot and collapse did not occur. Contrary to popular belief (and the belief of many who should know better), Malthus did not predict a future in which population would outrun food supply and eventually collapse.
Other critics write that Malthus was wrong because he did not take into account the possibility of dramatic increases in the production of food. Many criticize him for not taking into account the revolution in agriculture. But he anticipated this argument as well:
No limits whatever are placed to the productions of the earth; they may increase for ever and be greater than any assignable quantity, yet still the power of population being a power of a superior order, the increase of the human species can only be kept commensurate to the increase of the means of subsistence by the constant operation of the strong law of necessity acting as a check upon the greater power (9-10).
It makes no difference how much productivity increases, Malthus writes, it could not long keep up with unrestrained reproduction. Population must be constantly checked to keep it in line with what the earth can produce. While it has become a commonplace in the literature to claim that increased productivity has disproved Malthus’s main contention of the need for population checks this is simply not the case. Assuming 700 million people at the time of the Essay (an estimate widely reported in the literature, and a 25-year doubling time for unchecked population (what modern demographers call “fecundity”), today’s population would now be close to 48 billion. It is not nearly so high (7 billion as of this writing) because there have been constant checks on population in the last 200 years. While food productivity has increased substantially, it has not (nor could it) increase at the same rate as unchecked population growth. Rather, in accordance with Malthus’s theory, the rise in productivity in the last 200 years has been met by a substantial rise in population a rise that has been truly exponential though far less than potential unchecked growth.
What are these checks that Malthus writes about? They are of two types: “Preventive checks” come into play through the “foresight of the difficulties attending the rearing of a family” (22). They include celibacy, contraception, and various forms of non-procreative sex. “Positive checks,” are the “actual distresses of some of the lower classes, by which they are disabled from giving the proper food and attention to their children” (22). Under this heading Malthus includes extreme poverty, diseases, plague, malnutrition, wars, infanticide, and famine. Positive checks are far more likely to operate within poor populations; preventive checks among the upper classes. In Malthus’s view, both positive and preventive checks—or the ways a people go about controlling their fertility—will greatly impact the rest of the sociocultural system.
Malthus’s principle of population is basically the law of supply and demand applied to the relationships between food production and population growth, which he makes clear time and again throughout the Essay. As the food supply increases, food becomes cheaper, and more children are brought into the world. As there are more mouths to feed, food becomes more expensive, thus causing stress on families, more children dying or steps taken to prevent conception itself. As food prices rise, more land is put under the plow, or greater efforts made in intensifying the production of the land itself.
While Malthus recognized that the relationships among the fertility of people and land are a good deal more complex than this simplified assertion, he maintained there is a recurrent reciprocal relationship between the two. Because of this reciprocal relationship between population and production, over the course of sociocultural evolution, both population and food production have grown in tandem. Periods of increase in food productivity, whether because of the application of technology or the expansion of cultivated land, have been met with expansions of population. Periods of stability in food production, or contraction in productivity, have been marked by the same phenomena in population level.
Because people can reproduce faster than they can increase the production of food, population must always be checked through positive or preventive means. This and nothing more, is Malthus’s “Principle of Population.” Over the course of sociocultural evolution, however, the long-term tendency has been for both productivity and population to intensify. This reciprocal growth, of course, has great effect on other parts of the sociocultural system.
For a more extensive discussion of Malthus’s theories refer to Macro Social Theory by Frank W. Elwell. Also see Sociocultural Systems: Principles of Structure and Change to learn how his insights contribute to a more complete understanding of modern societies.
Elwell, F. (2009), Macrosociology: The Study of Sociocultural Systems. Lewiston: Edwin Mellen Press.
Elwell, F. (2013), Sociocultural Systems: Principles of Structure and Change. Alberta: Athabasca University Press.
Malthus, T. R. (Thomas Robert) (2012-05-12). An Essay on the Principle of Population. Kindle Edition.
Referencing this Site
To reference Malthus'sPopulation Principle Explained you should use the following format:
Elwell, Frank W., 2003, "Malthus's Population Principle Explained," Retrieved August 31, 2013, [use actual date] http://www.faculty.rsu.edu/~felwell/Theorists/Essay/Malthus1.htm
©2013 Frank Elwell, Send comments to felwell at rsu.edu