Malthus and Population Pressure

Thomas Malthus, 1766-1834 (Wikimedia Commons)

-An Essay on the Principle of Population as It Affects the Future Improvement of Society, with Remarks on the Speculation of Mr. Godwin, M. Condorcet, and other Writers (1798)

-An Essay on the Principle of Population, or a View of its Past and Present Effects on Human Happiness, with an Inquiry into our Prospects respecting the Future Removal or Mitigation of the Evils which it occasions (1803; note the change in emphasis from the 1st edition)

-Principles of Political Economy considered with a view to their Practical Application (1820)

Malthus famously holds that while the rate of unchecked population growth is geometrical, the rate of growth in the means of subsistence will only grow at an arithmetical rate. According to him, the checks that keep down the population can be divided into "positive" and "preventive or moral." Positive checks are misery and vice, and the moral check is abstinence from procreation. Hence unless the population can be kept down by abstaining from conceiving children, society is doomed to have a large population of miserably poor people at subsistence level, many of whom will die young of famine or disease, and many who grow to adulthood will die by need-induced violence. All people, he held, are engaged in "the struggle for existence," just as are the animals. And the poor and unfortunate are especially likely to succumb in that struggle, which is worsened by population pressure. In the first (1798) edition of his Essay on the Principle of Population, Malthus took this to show that the society of equals desired by many of his radical friends was impossible.

Interestingly, John Stuart Mill and his fellow utilitarians--political radicals, all--accepted and championed this theory, taking it to be an excellent argument for birth control, which they publicly advocated.

Malthus, then, put into general circulation the idea of the pressures of overpopulation and how they sharpen and intensify the struggle for existence. This idea Charles Darwin took as the tool that unlocked the mystery of the evolution of species. Darwin reasoned as follows. Suppose individual members of species face these pressures of overpopulation, and suppose further that their results an intensifying struggle for existence among them. Then those individuals best able to succeed in the struggle would leave behind surviving progeny who themselves survived and left behind surviving progeny. These individuals best adapted to the struggle would thus see their particular traits reproduced and handed down. Gradually,

these changes would lead to extinctions of whole species, as well as changes from one species to another. From this mechanism and its fit with the evidence and other accepted theories, he inferred that the mechanism was real. The mechanism he called "natural selection," and he acknowledged that Malthus's ideas of population pressure and the struggle for existence are key players in the theory of evolution by natural selection. Thus did two key concepts of Malthus--which he initially developed to challenge radical egalitarian social programs--become central to evolutionary theory. Economic ideas had massively influenced the progress of biology.

But the story of Maltus's concepts did not end there. For they almost immediately returned, with Darwin's theory as their vehicle, to transform economic and political theory. On the one hand, they figured centrally in a new justification of laissez-faire capitalism, due to Herbert Spencer and William Graham Sumner. On the other hand, they were central to a new justification for anarchism, due to Peter Kropotkin.

Malthus's Idea of the Causes and Effects of Unchecked Population

http://digitalcollections.library.yale.edu/GroupsView.aspx?qid=5092

Malthus's Principles are also a distinguished contribution to economic theory. Among other things, he famously argues that there can be overproduction in an economy and a continuing shortage of demand. He thus rejects Say's Law, according to which economy-wide demand will always meet economy-wide supply: there cannot be a general and continuing shortage of demand for the goods that have been produced (though of course there can be particular shortages of demand in particular sectors or industries). By the 1860s or so, Say's Law had become a fundamental creed of economics: to reject it was a heresy. Malthus was therefore relegated to the dustbin of economics, remembered only for his contribution to population theory. Then, when the Great Depression hit, John Maynard Keynes rediscovered Malthus's critique of Say's Law and defense of the possibility of underconsumption. Keynes centered the General Theory around a refutation of the Law and the possibility of an equilibrium of underconsumption and unemployment. The refutation succeeded: economists relegated Say's Law to the dustbin, and thus rehabilitated Malthus's reputation as an economic theorist.

Malthus was a friend, correspondent, and debater of David Ricardo, the great founder of classical economics and defender of Say's Law. The two of them had different conceptions of the main tasks of economics. As Ricardo wrote to Malthus in a letter of October 1820, "Political Economy you think is an enquiry into the nature and causes of wealth--I think it should rather be called an enquiry into the laws which determine the division of the product of industry amongst the classes who concur in its formation."