Malthus and American History

At the end of the eighteenth century, a little over two decades after Americans declared their independence from Great Britain, the Reverend Thomas Malthus published An Essay on the Principle of Population in London.¹ The book was an immediate sensation and Malthus reissued and revised the study for the next several decades.² During Malthus’ lifetime and since, his ideas have been popularized, vilified, praised, and dismissed. In later editions of the work, Malthus himself effectively reversed some of his initial conclusions in the 1798 edition. Thus it is quite challenging to nail down definitively both what Malthus himself actually wrote and what his critics and disciples claimed he said. “Malthusianism” or “Malthusian population theory” is a slippery animal.

Malthus explicated, in accessible form, a theory of the relationship between human population growth and the economic resources required to support human life. As Alan Macfarlane has written in the International Encyclopedia of the Social Sciences (2^nd edition):

Malthus’ theory in brief was that humankind is permanently trapped by the intersection of two “laws.” The first concerned the rate at which populations can grow. He took the “passion between the sexes” to be constant and investigations showed that under conditions of “natural” fertility (with early marriage and no contraception, abortion or infanticide), this would lead to an average of about fifteen live births per woman. . . . Given normal mortality at the time, and taking a less than maximum fertility, this will lead to what Malthus called geometrical growth, namely 1, 2, 4, 8, 16. . . .

The second premise was that food and other resource production will grow much more slowly. It might double for a generation or two, but could not keep on doubling within an agrarian economy. Thus there could, in the long run, only be an arithmetic or linear growth of the order of 1,2,3,4. Incorporated in this later theory was the law of diminishing marginal returns on the further input of resources, especially labour. . . . Populations would grow rapidly for a few generations, and then be savagely cut back. A crisis would occur, manifesting itself in one (or a combination) of what he called the three “positive” checks acting on the death rate, war, famine and disease.³

Figure one illustrates the theory.

Figure 1.

Arithmetic vs Geometric Growth

The increasing gap between population and resources would generate a “Malthusian crisis.” In later editions of the Essay, Malthus moderated this bleak view of the fate of humankind by suggesting that the disasters of overpopulation could be avoided by what he called a “preventive” check on fertility. He proposed that the extreme geometric growth rate slope could be moderated by late marriage and/or celibacy for significant numbers of people (Figure 2), though he remained pessimistic that the gap between resources and population could actually be closed.

Figure 2.

Growth Modified

Malthus’ theories and predictions were primarily aimed at describing British and European demographic realities, and hence influencing British public policy. Rising populations had provoked vigorous debate about whether such population growth was to be encouraged or was a potentially ominous trend likely to lead to catastrophe at some point in the future. Adam Smith had famously commented that “the most decisive mark of the prosperity of any country is the increase of the number of its inhabitants.”⁴ But Malthus’ predictions seemed all too prescient given the turmoil of the French Revolution and the Napoleonic Wars, the obvious misery of the poor, and the historical record of disastrous disease epidemics of the past. The policy question that Malthus’ theories raised was whether a society or humankind as a whole could avoid a Malthusian...