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Tr Malthus An Essay On The Principle Of Population Theory

Thomas Malthus biography
Essay on the Principles of Population

Thomas Malthus was born near Guildford, Surrey, England in 1766 into a well-off family. He was educated from 1784 at Jesus College, Cambridge where he achieved distinguished marks in his mathematical studies. He was subsequently ordained as an Anglican cleric in 1797 despite having an inconvenient speech impediment. He became curate of the parish of Albury in Surrey in 1798 and held this post for a short time.

His main contribution is to Economics where a theory, published anonymously as "An Essay on the Principle of Population" in 1798 has as a central argument that populations tend to increase faster than the supply of food available for their needs.

To quote directly from the essay:-

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

The essay thus anticipated that this propensity could only lead to real distress:-

" The number of labourers also being above the proportion of work in the market, the price of labor must tend towards a decrease; while the price of provisions would at the same time tend to rise".

This theory of the effective inevitability of poverty and distress contradicted the optimistic belief prevailing in the early 19th century, that a society's fertility would lead to economic progress and helped to give Economics, then more frequently known as "Political Economy" the alternative name of "The Dismal Science."

Earlier that year the British statesman William Pitt had proposed that poor relief should give special consideration to the encouragement of large families as "those who, after having enriched their country with a number of children, have a claim upon its assistance for their support." In the event Malthus's theory was often used as an argument against efforts to better the condition of the poor.

Malthus later went so far as to suggest that, for the lessening of the probability of a miserable existence for the poor, it was advisable to seek to cut the birth rate in society. This suggestion was unmistakably outrageous given the moralities of the times (and would doubtless be most controversial today).

The Essay on the Principle of Population and other writings encouraged the first systematic demographic studies and also had a significant influence in several ways:-

In Economics David Ricardo's, "iron law of wages" and theory of distribution of wealth contain some elements of Malthus' theory.

Thomas Malthus' Essay on Population
Charles Darwin and
Alfred Russel Wallace

Of far more dramatic significance is the fact that both Charles Darwin and Alfred Russel Wallace admitted that the food scarcities regarded as being normal by Malthus had been of KEY influence on their seperate development of theories of the evolutionary Origin of Species.

To use Charles Darwin's own words from his Autobiography speaking about a time late in 1838 when Malthus ideas were of the utmost importance in guiding the future direction of his own thinking:-

I happened to read for amusement Malthus on 'Population', and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable 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.

Words from another Autobiography, this time one by Alfred Russel Wallace, are also available to us as evidence of the massively significant influence of Thomas Malthus Essay on the Principle of Population.

It was in 1858 whilst he was laid up with a malarial fever at Ternate, in the Celebes Islands, that a possible solution to the method of evolution flashed into form in Wallace's mind. The outcome being that this burst of inspiration together with his more longstanding ruminations resulted in Alfred Russel Wallace independently framing a theory of the evolutionary origin of species by natural selection.

At the time in question I was suffering from a sharp attack of intermittent fever, and every day during the cold and succeeding hot fits had to lie down for several hours, during which time I had nothing to do but to think over any subjects then particularly interesting me. One day something brought to my recollection Malthus's "Principles of Population", which I had read about twelve years before. I thought of his clear exposition of "the positive checks to increase" - disease, accidents, war, and famine - which keep down the population of savage races to so much lower an average than that of more civilized peoples. It then occurred to me that these causes or their equivalents are continually acting in the case of animals also; and as animals usually breed much more rapidly than does mankind, the destruction every year from these causes must be enormous in order to keep down the numbers of each species, since they evidently do not increase regularly from year to year, as otherwise the world would long ago have been densely crowded with those that breed most quickly. Vaguely thinking over the enormous and constant destruction which this implied, it occurred to me to ask the question, Why do some die and some live? And the answer was clearly, that on the whole the best fitted live. From the effects of disease the most healthy escaped; from enemies, the strongest, the swiftest, or the most cunning; from famine, the best hunters or those with the best digestion; and so on. Then it suddenly flashed upon me that this self-acting process would necessarily improve the race, because in every generation the inferior would inevitably be killed off and the superior would remain - that is, the fittest would survive. Then at once I seemed to see the whole effect of this, that when changes of land and sea, or of climate, or of food-supply, or of enemies occurred - and we know that such changes have always been taking place - and considering the amount of individual variation that my experience as a collector had shown me to exist, then it followed that all the changes necessary for the adaptation of the species to the changing conditions would be brought about; and as great changes in the environment are always slow, there would be ample time for the change to be effected by the survival of the best fitted in every generation. In this way every part of an animal's organization could be modified exactly as required, and in the very process of this modification the unmodified would die out, and thus the definite characters and the clear isolation of each new species would be explained. The more I thought over it the more I became convinced that I had at length found the long-sought-for law of nature that solved the problem of the origin of the species. For the next hour I thought over the deficiencies in the theories of Lamarck and of the author of the "Vestiges," and I saw that my new theory supplemented these views and obviated every important difficulty. I waited anxiously for the termination of my fit so that I might at once make notes for a paper on the subject. The same evening I did this pretty fully, and on the two succeeding evenings wrote it out carefully in order to send it to Darwin by the next post, which would leave in a day or two.

I wrote a letter to him in which I said I hoped the idea would be as new to him as it was to me, and that it would supply the missing factor to explain the origin of the species. I asked him if he thought it sufficiently important to show it to Sir Charles Lyell, who had thought so highly of my former paper.

From Alfred Russel Wallace : My Life, pp. 360-363.

And so it was that Wallace sent a memoir about this evolutionary theory to the influential expert naturalist Charles Darwin, arrived in Darwin's hands in June 1858. In a covering letter Wallace asked that Darwin forward the memoir to a famous scientist, Sir Charles Lyell, if Darwin thought the content merited his attention.

Darwin had not intended to publish his own theorisings but this approach by Wallace forced his hand. The unfolding scenario in which these events took place are more fully considered on our page about the development of Evolutionary Theory independently by Charles Darwin and Alfred Russel Wallace.

Darwin and Wallace's independent routes to developing
their similar views of the Evolution of Species

From 1805 until his death Thomas Malthus was Professor of Modern History and Political Economy at the newly established college of the East India Company at Haileybury. This appointment may have been the first professional post in Economics held by anyone in human history.

Other works include An Inquiry into the Nature and Progress of Rent (1815) and Principles of Political Economy (1820).

Malthusian Theory of Population


Thomas Robert Malthus was the first economist to propose a systematic theory of population.  He articulated his views regarding population in his famous book, Essay on the Principle of Population (1798), for which he collected empirical data to support his thesis. Malthus had the second edition of his book published in 1803, in which he modified some of his views from the first edition, but essentially his original thesis did not change.


In Essay on the Principle of Population,Malthus proposes the principle that human populations grow exponentially (i.e., doubling with each cycle) while food production grows at an arithmetic rate (i.e. by the repeated addition of a uniform increment in each uniform interval of time). Thus, while food output was likely to increase in a series of twenty-five year intervals in the arithmetic progression 1, 2, 3, 4, 5, 6, 7, 8, 9, and so on, population was capable of increasing in the geometric progression 1, 2, 4, 8, 16, 32, 64, 128, 256, and so forth.  This scenario of arithmetic food growth with simultaneous geometric human population growth predicted a future when humans would have no resources to survive on.  To avoid such a catastrophe, Malthus urged controls on population growth. (See here for graphs depicting this relationship.)   


On the basis of a hypothetical world population of one billion in the early nineteenth century and an adequate means of subsistence at that time, Malthus suggested that there was a potential for a population increase to 256 billion within 200 years but that the means of subsistence were only capable of being increased enough for nine billion to be fed at the level prevailing at the beginning of the period. He therefore considered that the population increase should be kept down to the level at which it could be supported by the operation of various checks on population growth, which he categorized as "preventive" and "positive" checks.


The chief preventive check envisaged by Malthus was that of "moral restraint", which was seen as a deliberate decision by men to refrain "from pursuing the dictate of nature in an early attachment to one woman", i.e. to marry later in life than had been usual and only at a stage when fully capable of supporting a family. This, it was anticipated, would give rise to smaller families and probably to fewer families, but Malthus was strongly opposed to birth control within marriage and did not suggest that parents should try to restrict the number of children born to them after their marriage. Malthus was clearly aware that problems might arise from the postponement of marriage to a later date, such as an increase in the number of illegitimate births, but considered that these problems were likely to be less serious than those caused by a continuation of rapid population increase.


He saw positive checks to population growth as being any causes that contributed to the shortening of human lifespans. He included in this category poor living and working conditions which might give rise to low resistance to disease, as well as more obvious factors such as disease itself, war, and famine. Some of the conclusions that can be drawn from Malthus's ideas thus have obvious political connotations and this partly accounts for the interest in his writings and possibly also the misrepresentation of some of his ideas by authors such as Cobbett, the famous early English radical.  Some later writers modified his ideas, suggesting, for example, strong government action to ensure later marriages. Others did not accept the view that birth control should be forbidden after marriage, and one group in particular, called the Malthusian League, strongly argued the case for birth control, though this was contrary to the principles of conduct which Malthus himself advocated.


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