Malthus – The Principle Of Population

The Principle Of Population In Classical Economics: Thomas Malthus

If the principle of utility was one cornerstone of classical economics, the pop­ulation principle was another. The writer who gave classical population theory its definitive statement was Thomas Robert Malthus (1766-1834). John Maynard Keynes called him the "first of the Cambridge economists," for it was at Cambridge that Malthus distinguished himself as an undergraduate in Jesus College. There Malthus prepared himself for a ministerial career. De­spite a congential cleft palate, he won prizes for his declamations in Greek, Latin, and English. He graduated in 1788 and took holy orders the same year, but he remained at Cambridge as a graduate fellow until 1804, at which time he married and thereby had to resign his fellowship, according to the rules of the

Malthus's father counted Jean-Jacques Rousseau and David Hume among his friends, both of whom are reputed to have been young Thomas's first vis­itors when he was an infant. As he grew older, Malthus was educated privately and learned to be an independent thinker, a trait that he later put to good use in establishing his theory of population. In 1798 Malthus published, anony­mously, An Essay on the Principle of Population as It Affects the Future Im­provement of Society, with Remarks on the Speculations of Mr. Godwin, M. Condorcet, and Other Writers. Anonymity, however, quickly gave way to gen­eral recognition, and in due course, Malthus's name became a household word.

The full title of the Essay hints at the motivation behind it. Malthus reacted against the extreme optimism of the philosophers Godwin and Condorcet. In­spired by the political euphoria of the French Revolution, these two philosophers forecast the elimination of social evils. They described a society devoid of war, crime, government, disease, anguish, melancholy, and resentment, where every man unflinchingly sought the good of all. Malthus's answer to the Godwin-Condorcet vision appears, in retrospect, to be deceptively simple: The biological capacity of man to reproduce will, if left unchecked, outstrip the physical means of subsistence, he stated, and in consequence render the perfectibility of human society impossible.

The first Essay was constructed largely in Malthus's own head. Afterward, and partly because of the furor it created, he began to add some empirical flesh to his bare-bones theory. The Essay went through subsequent editions in 1803, 1806, 1807, 1817, and 1826. Finally, it culminated in A Summary View of the Principle of Population, published in 1830. Despite numerous modifications through its several editions, however, the essential principle of the first Essay remained unchanged.

An Outline of the Theory

Malthus based his population principle on two propositions. The first asserted that "Population, when unchecked, increases in a geometrical progression of such a nature as to double itself every twenty-five years" (A Summary View, p. 238). Malthus attempted to add precision to this principle by basing it on population experience in the United States. Available statistics were unreli­able, however, and provided little real empirical support for Malthus's first postulate. Consequently, he was careful to indicate that this doubling of pop­ulation every twenty-five years was neither the maximum growth rate of pop­ulation nor always necessarily the actual rate. But Malthus clearly asserted the existence of a potential growth rate of population that advanced in geometric progression.

Counterpoised to the first postulate was the second: Under even the most favorable circumstances, the means of subsistenc can not possibly increase faster than in arithmetic progression. The precision that Malthus lent to this second assertion was unfortunate, since the arithmetic progression of the food supply could not be supported by fact, not even as loosely as the first assertion could. Nevertheless, juxtaposition of the first two postulates led to recognition of the obvious discrepancy between the potential growth of population versus the food supply. In Malthus's own words: "The power of population being.. .so much superior, the increase of the human spe­cies can only be kept down to the level of the means of subsistence by the constant operation of the strong law of necessity, acting as a check upon the greater power" (A Summary View, p. 21).

This population dilemma posed both a theoretical and a practical question. The theoretical question centered on identification of the actual checks to pop­ulation growth; the practical question concerned solutions to the problem, namely, which checks should be encouraged over others. Malthus discussed both questions, beginning with the identification problem.

Positive and Preventive Checks

The ultimate check on population growth is limited food supply. But there are others, and Malthus classified them into positive checks and preventive checks. The former, such as disease, increase the death rate, whereas the latter, such as contraception, lower the birthrate. Malthus himself favored neither contraception nor abortion as practical means to circumscribe population growth. In a carefully measured condemnation of the latter, he described abortion as "improper arts to conceal the conse­quences of irregular connection"!

The significance of Malthus's contribution lay in his ability to fashion the procreative tendency and the checks to it into a theoretical structure that fo­cused attention on those forces tending to change the number of people on earth. Table 6-1 presents Malthus's population theory in summary form.

As theory, the population principle tells us that population will increase whenever the cumulative effect of the various checks is less than that of pro­creation, that it will decrease whenever the cumulative effect of the checks is greater than that of procreation, and that it will remain unchanged whenever the combined effects of the checks and of procreation are self-canceling.

Theoretical Limitations

Although the theory outlined in Table 1 is quite general, Malthus himself tended to view the outcome of the population-food supply struggle as inevitably leading to a subsistence economy. This view was unfortunate for two reasons: (1) as prophecy, it has proved to be wrong in many instances, and (2) it is not at all inherent in the theoretical structure de­vised by Malthus.

On the one hand, Malthus's population theory is neutral with respect to as­sumptions and conclusions. Given relevant empirical inputs for Table 1, the theory is capable of explaining all manner of population changes: growth, de­population, or stagnation. On the other hand, Malthus inferred the actual at­tainment of a subsistence economy because the tendency to procreate would in fact dominate the cumulative effect of the checks in force. Malthus asserted that this consequence was inevitable, although, in fact, the advanced econo­mies of the world have so far managed to avoid it.

Table 1

Malthus’s Distinction Between Positive and Preventive Checks

Positive checks (factors increasing deaths) War Famine Pestilence

Preventive checks (factors reducing births) Moral restraint Contraception Abortion

Does this mean as theory, Malthus's population principle is invalid? Not necessarily, for his theoretical structure is quite capable of yielding general conclusions regarding population and subsistence for different economies at different historical periods. What is required to make the theory operational in a predictive sense, however, is reliable information about the magnitude of the tendencies given prominence by the theory.

Malthus may also be faulted for overlooking other checks that might fore­stall his gloomy conclusion. For one thing, he failed to separate, conceptually, sex and procreation. Yet in a world of modern birth control techniques and other arts of family planning, the distinction is often made. Many families limit the number of their offspring for reasons other than financial ones, e.g., a de­sire for personal freedom and mobility or a career. One cannot discount alto­gether the "cosmetic motive" for birth control—too many children may dam­age the appearance, comfort, and well-being of the mother. These additional checks are capable of reducing the disparity between multiplication of the spe­cies and growth of the food supply.

A more serious shortcoming of Malthus's population theory was his ten­dency, shared by other classical writers, to underestimate the advance of ag­ricultural technology. There was already the hint in the Essay that agriculture is subject to diminishing returns, a topic that Malthus later expanded in his theory of rent. As an economic law, however, diminishing returns hold only for a constant state of technology. And in the advanced economies rapid progress in technology has so far succeeded in forestalling the Malthusian specter. This does not, of course, deny the very real threat of subsistence in the underdeveloped world. There the Malthusian specter appears to be a gen­uine threat to the practical objective of economic growth and development.