July 11 marked World Population Day, observed by the United Nations (UN) each year since 1989. It was established after the human population of Earth reached 5 billion on July 11, 1987 to, “…focus attention on the urgency and importance of population issues.” As of July 11, 2019 the human population has reached 7.7 billion and is projected to reach nearly 10 billion by 2050. Continued overall positive population growth, combined with a general upward trend in worldwide human life expectancy, has created concerns about overpopulation: that is, a situation in which the resources of particular regions—or the planet in general—are outstripped by the needs of the human population.
Concerns about human population are not new. Throughout history, legislators and scholars across cultures have been concerned with either depopulation, overpopulation, or population density. In Ancient China, Kongzi (Confucius) advocated government policy to ensure a balanced distribution of people across the arable land of China. Mozi, though a critic of Confucianism, also advocated government policy concerning population. One of the three moral/political criteria for beneficial actions (利, “lì”) in Mozi’s philosophy was that it promoted population growth. In Ancient Greece, Plato fixed the ideal population of a city-state at around 50400 (accounting for 5040 citizens, and then other non-citizens such as women, children, and slaves). Aristotle criticizes Plato’s calculations for not taking into account issues with fertility rates, mortality rates, and the size of territory required to sustain a population. In the Middle Ages, the Islamic philosopher Ibn Khaldun wrote extensively on population dynamics, advocating for denser population centers to facilitate social and economic prosperity.
Much of the contemporary discussion of human overpopulation is traceable to Richard Malthus’ 1798 “An Essay on the Principle of Population.” Malthus provides a mathematical argument as the basis of his thesis that overpopulation was a problem that would steadily grow worse: human population grows exponentially while the food supply only grows linearly. That is, the increase in food production occurs at a rate which remains the same over time whereas the increase in population occurs at a rate which itself increases over time. Malthus’ view of the problem focused on the poor and destitute, whom he viewed as those whose position was more vulnerable to famine and disease. These twin killers are examples of what Malthus referred to as positive checks on population: calamities that arise naturally from overpopulation and serve to check population growth. Allowing population to grow until checked by such natural forces was cruel in Malthus’ view. He argued that the better measures were so-called preventative checks: e.g., abstaining from or delaying procreation.
In the current day, there is significant sympathy with the preventative aspect of the Malthusian position. In light of the growing population, and ever-increasing evidence that human activity is a primary driver of climate change, some people believe that having children is immoral. Or, at least that it is a decision which has to be made in response to the issues facing the world—and not narrower personal or familial ones. Other contemporary scholars have generated their own strands of reasoning to argue against procreation—or at least against the presumption that a decision to have children stands in need of no special justification. In general, arguments to the effect that procreation is immoral are referred to as anti-natalist views. Canadian philosopher Christine Overall and South African philosopher David Benatar both provide their own versions of anti-natalism.
Overall, in her book Why Have Children, canvasses the usual arguments both for and against having children and finds them all lacking. She concludes that the decision to have children always stands in need of justification, and that the justification must be given in terms of the possibility of a healthy relationship developing between parents and children. Benatar, on the other hand, argues that human existence is generally characterized by misery. Because of this he argues that it is always bad to bring new life into the world. In other words, whereas Overall claims that having children can possibly be justified—though not in any of the usual ways—Benatar argues that having children is always unjustified. In his Better Never to Have Been, Benatar claims that life is bad—but so is death and dying. The only way to avoid this double-bind is to never have existed in the first place. (Incidentally, the sort of arguments Benatar gives are among the types of arguments Overall finds lacking.)
In the broad sweep of history, anti-natalist views rise and fall with the population itself. At times when populations have significantly decreased, arguments arose advocating having more children. Barring the success of a general anti-natalist argument like Benatar’s, issues about overpopulation are broadly about resources and climate. Given the dire warnings and predictions about the state of Earth’s climate future, sympathy with anti-natalist positions will likely continue or even increase.