Population Ethics: I. Elements of Population Ethics: C. History of Population Theories

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Ancient and Medieval Theories

Like most general theories of Western civilization, those concerning population evolved first in ancient Greece. Both policies and their conceptual frameworks varied in their details, but there was much consistency from one city-state to another. The typical pronatalist policies were intended not to induce a growth in numbers but to prevent their decline (Stangeland, chap. 1; Hutchinson, chap. 2). In the ideal city-state that Plato pictured in Laws, the population was to be kept stable at 5,040 (the product of 1 × 2 × 3 × 4 × 5 × 6 × 7) by encouraging or inhibiting fertility or by infanticide. If the population grew much beyond this optimum, the community was to establish colonies. To neglect measures that would keep the population more or less fixed, according to Aristotle, would "bring certain poverty on the citizens, and poverty is the cause of sedition and evil" (Politics, 2.9).

Greek thought on population, in sum, was characterized by an overriding concern with policy, and thus a relative indifference to empirical or conceptual analysis. Policy was to be applied, moreover, to aggregates ridiculously small by present-day standards. And whether the meaning of population was in accord with the modern sense is often not clear; in most instances the term may have referred only to citizens, thus omitting females, children, slaves, and aliens.

In its far larger arena, Rome's policy was more consistently pronatalist. As imperial hegemony spread from Italy throughout the Mediterranean basin and beyond, the center was troubled by moral decay, the dissolution of the family, and a slower growth of population. Successive pronatalist measures culminated in three enactments under Augustus (63 b.c.e.–14 c.e.), which punished celibacy and adultery and rewarded prolific couples (Stangeland, pp. 30–38). Since they had little apparent effect, the laws were repeatedly amended and finally repealed under Constantine (ca. 288–337).

As the empire gradually disintegrated, many came to believe that the end of the world was imminent, and various sects offered competing dogmas appropriate to the apocalypse. The early Christian church gradually developed its own doctrine with a compromise between libertine and ascetic, but emphasizing the latter (Noonan). Catholic thought reached its apogee in the Summa Theologica of Thomas Aquinas (ca. 1224–1274). For him, a marriage between Christians is not merely a means of obeying the injunction to replenish the earth but also a spiritual bond, a sacrament. The function of intercourse is procreation (Bourke).

Early Modern Theory

The dominant theme of the early modern period was the view that population growth is precarious and has to be fostered. Just as the mercantilist state hoarded gold, so it hoarded people, and for the same reason—to increase its economic, political, and military power. If rapid population growth resulted in what was termed "overcrowding," the mercantilist solution was to ship the surplus to colonies, where the settlers and their progeny could continue to aggrandize the state's power in another quarter of the globe.

Modern demography began with the efforts of mercantilist states to keep track of their populations (Glass). William Petty (1623–1687) was the first exponent of what he called "political arithmetic." John Graunt (1620–1674) constructed the first crude life table. Gregory King (1648–1712) calculated population estimates based on local enumerations, which he corrected for technical errors. On the Continent, Johann Peter Süssmilch (1707–1767) used Protestant parish records to estimate Prussia's fertility and mortality. Richard Cantillon (ca. 1680–1734) held that internal migration, deaths, and especially marriages (and therefore births) varied according to the prevailing standard of living and the structure of the demand for labor. François Quesnay (1694–1774), who founded what was later called physiocratic thought, analyzed the implicit bounds to population growth.

The philosophes of eighteenth-century France varied greatly on many issues, but most also found reason to favor policies stimulating population growth. Charles-Louis de Secondat, Baron Montesquieu (1689–1755), believed that the entire world had undergone depopulation and recommended pronatalist decrees. According to Voltaire (1694–1778), a nation is fortunate if its population increases by as much as 5 percent per century. Louis de St.-Just (1767–1794) held that one can usually depend on nature "never to have more children than teats," but to keep the balance in the other direction requires the state's assistance. By this notion of an equitable family law, as inspired by Jean-Jacques Rousseau (1712–1778), marriages should be encouraged by state loans, and a couple that remained childless after several years ought to be forcibly separated.

The two utopians that Thomas Robert Malthus opposed in the first edition of his Essay on the Principle of Population, William Godwin (1756–1836) and Marie-Jean Caritat, Marquis de Condorcet (1743–1794), focused their attention on the wholly rational age they discerned just over the horizon. According to them, in a world from which diseases had been wholly eliminated, the span of life would have no assignable upper limit. People would devote themselves to more important tasks than, in Condorcet's words, "the puerile idea of filling the earth with useless and unhappy beings."


Malthus summarized or contravened earlier ideas so effectively that, for more than a century and a half, subsequent theorists have generally taken him as a benchmark. Unfortunately, many references to "Malthusian" thought are based, at best, on the first edition of Essay on the Principle of Population rather than on the much enlarged and thoroughly revised later editions—or, at worst, on a total misunderstanding of what he stood for (Petersen, 1979, chap. 4).

Thomas Robert Malthus (1766–1834) was a professor at the newly founded East India College, occupying Britain's first chair in the new discipline of political economy. He spent much of his life collecting data on the relation between population and its social, economic, and natural environments, bringing his theory into accord with these facts and adjusting it to criticism. There were seven editions of the Essay in all.

According to the principle of population as expounded in the Essay, population, "when unchecked," doubles once every generation. Among "irrational animals" this potential is realized, and its "superabundant effects are repressed afterwards by want of room or nourishment." But rational human beings can consider the consequences of their reproductive potential and curb their natural drive. With humans, thus, there are two types of control of population growth: "preventive checks," the chaste postponement of marriage, and "positive checks," the deaths resulting from too large a population relative to its subsistence. Tension between numbers and food can have a beneficial effect: A man who postpones marrying until he is able to support a family is goaded by his sex drive to work hard, thus contributing to social progress. For this reason Malthus opposed contraceptives, for their use permits individual sexual gratification with no benefit to society.

Through the successive editions of the Essay, Malthus increasingly stressed the negative correlation between station in life and size of family. This, in his view, was the principal clue to solving what later became known as "the population problem." In order to bring the lower classes up to the self-control and social responsibility exercised by those with more money and education, Malthus asserted, the poor should be given more money and education. "The principal circumstances" that induce prospective parents to have fewer children are "liberty, security of property, the diffusion of knowledge, and a taste for the comforts of life." Those that tend to increase procreation are "despotism and ignorance." The thesis that upward mobility into the middle class effects a decline in fertility, though it is far less familiar than that relating population growth to food, is in retrospect Malthus's most important contribution.

For many decades Malthus's reputation was far below that of lesser social analysts. Recently it has become apparent that much of present-day demography was at least partly stimulated by Malthus and that those who denounced him as a false prophet had typically begun by misrepresenting his ideas.

Population Optima

Most of the populations that Malthus discussed tended to grow too rapidly relative to the available resources, and he recommended institutional checks to their fertility. But the extraordinarily rapid growth of the American colonies, whose population was doubling every twenty-five years, he held to be of great benefit. In other words, each country has an optimum size and rate of growth, depending on the social and economic conditions. Malthus neither used the term optimum nor developed the concept beyond an implicit statement, but he planted the seed of the theory. Malthus's principle that the population tends to increase by a geometrical ratio and food by an arithmetical ratio can be reformulated as a law of diminishing returns. If to a fixed acreage of land more and more labor is added, return per person may first rise but then will decline as the work force increases beyond its most efficient size. The first definition of "the optimum" was based on this schema: It is that population which under given conditions produces the highest per capita economic return.

Soon, however, the optimum came to mean simply "the best population," with each analyst furnishing a particular yardstick of what is "good." By this route the theory of population optimum could be regarded as a version of social choice theory, with a wide variety of open questions (Dasgupta). Should the population be related to the present institutional structure or to some supposed future ("socialism," for instance)? Should the criterion of "good" be economic welfare, military strength, the conservation of resources, or some combination of these? This conundrum is aggravated by the fact that optima vary greatly, according to the goal that society sets. And should the standard relate exclusively to the number of people or also to their age structure, rate of growth, level of skill, and other characteristics that affect how efficiently the society can operate?

Obviously, no judgment concerning "the optimum" can be very precise. Whether a country of western Europe, say, is underpopulated or overpopulated is less a demographic-economic measurement than a more or less arbitrary opinion. The norm can be applied meaningfully only at the extremes. The colonies that became the United States were definitely underpopulated, as Malthus pointed out. And in some of today's less developed countries, by the judgment of most demographers, the rapidly growing populations impede a rise in the people's well-being.


We are all born and we all die, but only some of us move from one place to another. Unlike fertility and mortality, migration is not a biological process. Indeed, many determinants of migration are political: Movements are subsidized, restricted, or forced, and the status of migrants in their new homeland depends on the state's laws on aliens. If we conceive of migration following the usual definition—as the relatively permanent movement of persons over a significant distance—the specifications "permanent" and "significant" must be set by more or less arbitrary criteria. Partly for this reason, migration statistics are generally imprecise and subject to capricious interpretation.

Migration changes the size of population and the rate of growth in the two areas involved, but usually not in the simple fashion that common sense suggests. Most migrants are young adults, and their movement changes the age structure, and thus the birth and death rates, in both areas. Given a sedentary population and a stimulus to emigrate, typically some leave and some do not. There is self-selection by age, sex, family status, and occupation, as well as possibly by intelligence, mental health, and independence of character. Since migration is not unitary, it cannot be analyzed in supracultural terms but must be differentiated even at the most abstract level with respect to the social conditions obtaining. Generalizations about migration, thus, developed mostly outside of standard population theories.

Demographic Transition

The number of people in the world is increasing at an unprecedented rate to unprecedented totals, and the basic reason is no mystery: Mortality has fallen sharply, and in many areas fertility has not. As originally formulated (e.g., Landry), this so-called demographic transition was conceived as taking place in three broad stages: (1) preindustrial societies, with high fertility more or less balanced by high mortality and a consequent low natural increase; (2) societies in transition, with continuing high fertility but declining mortality and a consequent rapid natural increase; and (3) modern societies, with both fertility and mortality stabilized at low levels and a consequent more or less static population. In its barest form this theory is one of the best-documented generalizations in the social sciences.

Collapsing the whole of human history into these three demographic types means, of course, that not only details but also important distinctions are passed over. When actual populations are reconstituted, so simplistic a theory often proves to be less a guide to research or policy than an invitation to misunderstanding. And this has been so concerning each of the three stages (Chesnais).

It is assumed that the mortality of primitive peoples was high relative to that in advanced societies, but estimates of the longevity in ancient times can hardly be very precise. Whether or not preindustrial peoples were warlike, lived in a favorable climate, developed cultural norms promoting cleanliness, and so on certainly influenced their death rates. And the usual formula—that since the mortality of primitive humans was high, their fertility must have been close to the physiological maximum if the group was to survive—is also questionable. From an early survey of contemporary primitive cultures, Alexander Carr-Saunders (1922) concluded that all of them included customs intended to restrict the increase of population. There is no reason a priori to postulate that all prehistoric peoples reproduced like unthinking animals, incurring the cost of a subsequent unnecessarily high mortality.

In stage two, the first steps toward a modern industrial society bring about a decline in mortality—but also often, contrary to the theory, a rise in fertility. Improved health can result in greater physiological ability to reproduce. Whatever means had been used to reduce population growth, such as infanticide in Tokugawa Japan, may not survive modernization. If the age at marriage had been set well past puberty, as in early modern western Europe, the institutions bolstering this norm often became less effective. Religious practices or taboos unintentionally inhibiting fertility, such as the one prohibiting the remarriage of widows in Hindu India, may dissipate. Most remarkably, family-planning programs can result in a rise in fertility, for if women are able to depend on controls later in their reproductive life, many begin childbearing at an earlier age. In short, the effect of modernization is partly to increase fertility and partly to decrease it (Heer).

Moreover, the early analysts of the demographic transition failed to forecast the decline of mortality in less-developed countries. Over the past two centuries or so, as the main advances were applied in medicine, surgery, public sanitation, agriculture, and nutrition, Western populations gradually improved in health and longevity. During the last several decades, however, some of the most recent techniques have been transferred to areas lacking most prior scientific controls; peoples cared for until recently by witch doctors acquired access to antibiotics. In Ceylon (now Sri Lanka), to take one striking example, the estimated expectation of life at birth increased from forty-three years in 1946 to fifty-two in 1947; the gain achieved in this one year had taken half a century in most Western countries.

Efforts to Reduce Fertility

Because of the continuing high fertility and the sharp decline of mortality in less-developed countries, their populations have grown at rates high enough to stimulate widespread control measures. Some of these programs have been successful, but many have achieved far less than their proponents hoped they would, in part because none has an appropriate theory underlying it.

Is a large and rapidly growing population indeed a problem? Leaders of the independence movements of pre-1940 European colonies held that their countries' poverty derived not from excessive procreation but from imperial misrule, and this view often persisted after independence. The very slow start of India's programs to check its population growth, for instance, was due in part to Jawaharlal Nehru's initial ambivalence. Among those who accept the thesis that too many people can impede modernization, proponents have often advocated either birth control or industrialization, as though one or the other were the sole relevant factor.

The theories underlying birth-control programs, often implicit rather than spelled out in papers, reports, or books, can be summed up in the following propositions:

  1. Elements of "traditional" society constitute the principal impediment to the spread of contraception. But, as we have noted, most traditional cultures include antinatalist tendencies and, on the other hand, modern nationalism is often strongly pronatalist.
  2. The most important variable in any program is the contraceptive means to be used. But the history of the West suggests that, given the will to reduce fertility, people will make effective use of whatever means are available to them—coitus interruptus and illegal abortion in France, postponed marriage or nonmarriage in Ireland, and so on.
  3. The agency through which contraception can be most effectively disseminated is the state. But this contradicts, again, the history of the decline of Western fertility, where officialdom typically opposed the private neo-Malthusian leagues and their successors.
  4. Population policy can be equated essentially with family policy: That is, zero population growth can be realized by inducing each pair of parents to have an average of only two children. But the rate of growth depends also on the proportion of the population that is of childbearing age, and in less-developed countries that is generally very high.
  5. It is so important that the population crisis be solved that policy-oriented action and knowledge-oriented research must be collapsed into a single operation. This procedure violates the scientific canon that truth can be effectively sought only in a setting made as value-free as possible. As a consequence, field workers and analysts are encouraged to accept spurious results as valid, for it is very difficult to ascertain the actual sentiments and behavior patterns of respondents.

In sum, the many attempts to reduce fertility in less-developed countries have typically been made with little regard to what had been learned from the prior decline in family size in the industrial West. Perhaps the best link between the two is the wealth-flow theory, so designated by John Caldwell. The crucial factor is whether children are productively useful to their parents and care for them in their old age; if so, as in African cultures he studied, the incentive is to procreate to the maximum feasible. If, however, parents incur net costs for the long-term care and education of their children, who generally contribute little to household finances, the inevitable tendency is to reduce the number brought into the world. By concentrating on the family budget, Caldwell (1982) was able to elucidate both the historical decline of fertility in the West and the partial success of family-planning programs in less-developed countries.

Theories of Population in Totalitarian Countries

A focus on economic or cultural factors can mean that political influences on fertility are bypassed. More generally, theories developed in the democratic West are in many respects ill suited to analyze such past totalitarian societies as the Soviet Union and Nazi Germany. Though their cultures differed greatly, these two countries had certain features in common, many of which related to population theory and its application.

  1. The Nazi party and the Communist party were defined as omnipotent, able to cope with any increase in population. According to the first Soviet delegate to the U.N. Population Commission, "I would consider it barbaric for the Commission to contemplate a limitation of marriages or of legitimate births, and this for any country whatsoever, at any period whatsoever. With an adequate social organization it is possible to face any increase in population" (quoted by Sauvy, vol. 1, p. 174; cf. Petersen, 1988).
  2. Population theory had the same purpose as any other science—to bolster the power of the party in power (Besemeres). In particular, the need of the totalitarian state for labor was reflected in theories on how to maintain a high rate of population growth and in such applications as family subsidies.
  3. Efforts to stimulate the birthrate, however, were hampered by the ruling party's hostility to the family, which by its legal and emotional links between generations helps to maintain a traditional opposition to radically new ideas and practices. Both Nazi Germany and the Soviet Union tried to establish institutions that could replace the family, such as brothels in which SS men could impregnate young women certified as racially pure, or the Soviet children's homes in which the state could convert orphans and the offspring of political dissidents into reliable instruments of the Communist party. But such substitutes never produced a large enough crop, and policy toward the family therefore vacillated in both countries.
  4. The need for a high fertility was enhanced by the recklessness with which sectors of the population designated as hostile or inferior were killed off. The terror most closely associated with the Nazis was the mass slaughter of Jews, based on the outpouring of writings on Rassenkunde (race science). More often Communists defined their victims as class enemies (though antagonism to ethnic minorities was also a constant element of Soviet life), but the difference was not fundamental: The slaughter began in different sectors of the population and was sometimes concentrated there, but in both cases it spread to the whole society (Hilberg; Conquest).
  5. Totalitarian ideology was based on what in German is called Stufenlehre, a doctrine of stages. All analysis, all planning, began not in the empirical present but in the inevitable perfect future, homogenized into a "classless" (Judenfrei, "Jewless") sameness. The road to this paradise could be seen clearly only by the Nazi party and the Communist party, whose function was to move the rest of the population toward its destiny. The ruthless terror that was often needed was warranted, thus, by the glorious community that would ensue.


Intellectual history includes few population theories in the narrow sense; most theories were developed as usually minor adjuncts to systematic statements about the society or the economy. Even this thin conceptual framework, however, may have profound ethical implications, for long before anything scientific was known about the determinants and consequences of population growth, statesmen, theologians, and scholars proposed—and their societies sometimes adopted as policies—rules of behavior allegedly suitable to their environment.

Until the modern era, the usual policy orientation was pronatalist, for it was generally assumed both that more people were better than fewer and that realizing a faster growth required state aid. Though not the first to take a contrary position, Malthus was by far the most important. Paradoxically, the greatly increased concern with policy in recent decades has not been accompanied by a more precise definition of goals. The judgment of whether a population is too large or too small obviously depends on a reasonably precise designation of the optimum, which has remained perhaps the most controversial concept in demography.

In past times, tyrants and conquering armies slaughtered many aliens, variously defined, but the combination of ruthless nationalism with scientific means of disposing of "inferior" sectors of the population is an innovation of the twentieth century. Partly because of a reaction against totalitarian genocide, demographers have given less systematic attention than warranted to such population characteristics as health or skill, though in many contexts these may be more important than mere numbers.

In recent decades the most striking characteristic of demography has been the attempt to dispense with theory in the solution of population problems widely recognized as critical. The substitution of "concern" for competence has not led, however, to many successes. In spite of the proliferation of antinatalist programs in less-developed countries and of the numbers of potential parents who accept the contraceptives made available, the world's population continues to grow at a rapid rate.

william petersen (1995)

SEE ALSO: Eugenics; Family and Family Medicine; Fertility Control; Infanticide; International Health; Public Health; Sustainable Development;Women, Historical and Cross-Cultural Perspectives; and other Population Ethics subentries


Besemeres, John F. 1980. Socialist Population Politics: The Political Implications of Demographic Trends in the USSR and Eastern Europe. White Plains, NY: M. E. Sharpe.

Bourke, Vernon J. 1967. "Thomas Aquinas, St." In Encyclopedia of Philosophy, vol. 8, pp. 105–116. New York: Macmillan.

Caldwell, John. 1982. Theory of Fertility Decline. New York: Academic Press.

Carr-Saunders, Alexander Morris. 1922. The Population Problem: A Study in Human Evolution. Oxford: Clarendon Press.

Chesnais, Jean-Claude. 1986. La transition démographique: Étapes, formes, implications économiques: Étude de séries temporelles (1720–1984) relative à 67 pays. Institut national d'études démographiques travaux et documents, cahier no. 113. Paris: Presses universitaires de France.

Conquest, Robert. 1990. The Great Terror: A Reassessment. New York: Oxford University Press.

Dasgupta, Partha. 1987. "The Ethical Foundations of Population Policy." In Population Growth and Economic Development: Issues and Evidence, pp. 631–659, ed. D. Gale Johnson and Ronald D. Lee. Madison: University of Wisconsin Press.

Glass, David V. 1973. Numbering the People: The Eighteenth-Century Population Controversy and the Development of Census and Vital Statistics in Britain. Farnborough, U.K.: Saxon House.

Heer, David M. 1966. "Economic Development and Fertility." Demography 3: 423–444.

Hilberg, Raul. 1973. The Destruction of the European Jews. New York: New Viewpoints.

Hutchinson, Edward Prince. 1967. The Population Debate: The Development of Conflicting Theories up to 1900. New York: Houghton Mifflin.

Landry, Adolphe. 1934. La révolution démographique: Études et essais sur les problèmes de la population. Paris: Librairie du Recueil Sirey.

Noonan, John Thomas, Jr. 1965. Contraception: A History of Its Treatment by the Catholic Theologians and Canonists. Cambridge, MA: Belknap Press.

Petersen, William. 1979. Malthus. Cambridge, MA: Harvard University Press.

Petersen, William. 1988. "Marxism and the Population Question: Theory and Practice." Population and Development Review 14 (supp.): 77–101, ed. Michael S. Teitelbaum and Jay M. Winter. Also published under the title Population in Western Intellectual Traditions. Cambridge, Eng.: Cambridge University Press, 1989.

Sauvy, Alfred. 1952. Théorie générale de la population. 2 vols. Paris: Presses universitaires de France.

Stangeland, Charles Emil. 1904. Pre-Malthusian Doctrines of Population: A Study in the History of Economic Theory. New York: Columbia University Press.

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Population Ethics: I. Elements of Population Ethics: C. History of Population Theories

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Population Ethics: I. Elements of Population Ethics: C. History of Population Theories