The quadrupling of the global human population during many people’s lifetime has changed the world tremendously. It has given rise to the name Anthropocene for this new era in which a single species irreversibly modifies the entire planet and its climate. In stark contradiction to that recognition, growth of our populations is predominantly perceived as something that happens to us, not by us. Any awareness of agency in population dynamics, personal or collective, is usually suppressed or denied. Most of the time, and in most cultures, we continue to treat the subject as a taboo entirely.

Those diverse ancient cultural taboos and restrictive norms hamper discussions of human agency or gender relations in the context of procreation and perpetuate unsustainable growth. The notion that a woman would voluntarily have a dozen children seems preposterous; if it happens involuntarily, it happens under oppression. The ubiquitous cultural predispositions towards population issues affect gender relations, structures of power and privilege, economic orders, social stratification, individual agency, and valuations of nature.

Nevertheless, the taboo has been perceptibly eroding lately.¹ Conservative organizations and decision-makers are quietly transitioning from denying the Anthropocene polycrisis towards adapting to its consequences. Cornucopian views regarding growth as boundless and inherently good are being challenged by hard evidence indicating the transgression of planetary boundaries and recommending donut economics.²

Throughout almost all of human history, population growth was not worth discussing; it didn’t exist. Populations remained more or less stable as a result of biological control mechanisms (infectious disease, malnutrition, behavioral reactions such as warfare and emigration) and through cultural adaptations (contraception, abstinence, abortion, infanticide).

All that changed with the onset of industrialization, colonization, and organized health care. Now, the scarcity of essential resources, and the ensuing conflict and suffering, are increasing. No progress has been made on the Sustainable Development Goals for the past two years.³ Our collective demand of ecosystem services exceeds 170% of what the biosphere can sustainably deliver.⁴ Waiting in the wings for their chance of a big comeback are famine and disease. I agree with Ian Lowe’s proposition that a Great Transition is proving ever less possible without effective and universal attention to population growth. Many moral arguments for such initiatives are based on anthropocentric considerations of the welfare and security of future generations. Ecocentric arguments point to the injustice behind ecological damage, accelerating species extinction, massive abuse and mistreatment of industrially “harvested” animals, and rampant destruction and displacement of wild nature by our sheer numbers. Fortunately, for once the two ethics do not contradict each other but reinforce the argument for pursuing ecologically defined ends.

ENDS

A Great Transition to a “sustainable, equitable, and desirable future” as advocated by Lowe amounts to “acceptable survival” according to Van Rensselaer Potter’s taxonomy of collective survival modes.⁵ Universally, what counts as acceptable is determined by the four pillars of human security—ensuring that basic sociopolitical, economic, health-related, and environmental needs are met in sustainable ways.⁶ This includes working for the sustainable well-being of all ecosystems that support our security in the future, limiting humanity’s impact on those ecosystems and reducing it where it has transgressed sustainable boundaries, and protecting and conserving the Earth’s remaining biodiversity.

Obviously, those requirements could be met for a population of a few million people in extreme comfort, or several billion in less comfort. As is reflected in the I=PAT equation, the difference manifests as different per capita allotments of affluence A and technological impact T.⁷ The total demand or impact I on the biosphere that humanity can hope to sustainably exert is at best constant. That means that the size of individual allotments that are claimed on average determines what size population P can be sustained. The model boils down to sharing a single pie as fairly as the guests around the table can agree on: admitting more guests means smaller shares, while baking more pies is hardly an option. The challenge lies in the negotiable details and the means: How small a share AT might be acceptable as a minimum claim? On whose authority should exorbitant claims be rejected and additional guests refused?

Our 170% overshoot indicates that the present product of PAT must be reduced, and as quickly as possible to minimize further damage (including climate change). The problem is that all three variables are still increasing. Neither greater equity nor stabilizing the world population will suffice to address the problem. All of the required measures will be unavoidably intrusive; however, they vary by degrees, by their extents of injustice, and by the moral boundaries involved, and they call for moral choices among means.

MEANS

While the ends are defined strictly by ecological models of bodies consuming resources, the means towards those ends are subject to ethical deliberation. The ends present tall challenges for a world order that cannot even seem to agree on a uniform system of shoe sizes in a global market. How could we hope to agree on the means in this much more critical endeavor? Dismantling taboos and discrediting their underlying values seem to be necessary starting points. As Lowe pointed out, although population reduction is an essential means towards sustainability, it is by no means sufficient even for addressing climate change alone; while the emission savings resulting from one fewer child dwarf all other measures, it is not sufficient just to reduce emissions.⁸

The I=PAT relationship also indicates that the size of the challenge to reduce population will be determined by how much we are willing to collectively, equitably, and fairly reduce our individual claims to resources. Much learning and unlearning will be required, at the levels of the individual and of collectives, to move towards greater frugality and to change procreative behavior.⁹ At the heart of that learning lies value change, without which no lasting change of behavior can be achieved.

At present, any attempt by governments to limit procreation is widely regarded as violating human rights. Some rights are universally grantable, such as human dignity and inviolability; other rights are resource-dependent and therefore cannot be granted under all circumstances.¹⁰ The “right to reproduce” falls into that category at this time. Targeted is the assumption that “want” makes a right, and the expectation of state subsidies for additional children and for reproductive technologies.

Solutions must aim at minimizing injustice when trading present day injustice for future welfare. Deliberations use John Rawls’s concept of reflective equilibrium.¹¹

Extending considerations of justice to other species, ecosystems, and to Gaia is not misanthropic but a long-overdue recourse to numerous indigenous ecocentric ethics.¹² It also turns our attention as stewards of nature to “managing ourselves.”¹³

A complementary requirement on the way towards population reduction is empowerment. It can amplify learning when it is experienced during the learning process. Political empowerment must be extended to individuals, especially women, and other disenfranchised groups, in order to support widespread action on newly adopted value priorities. The challenge is to extend empowerment from the economic into the political realm to destabilize patriarchy. This will in turn facilitate appropriate policy change.

Ethical decision-making and consensus-building can be expedited by urgent circumstances. While the urgency is evidently building, even superficial consensus still seems far out of reach. It might help us to take heed of the alternative, passively endured transition to a small population of survivors, enforced by Mother Nature through the most disagreeable means.

1. Books such as Trevor Hedberg’s on the ethics of procreation would likely not have seen publication even a decade ago: The Environmental Impact of Overpopulation: The Ethics of Procreation (Abington, UK: Routledge, 2020).
2. Environmental boundaries at multiple levels constrain human ambitions for growth: Linn Persson et al., “Outside the Safe Operating Space of the Planetary Boundary for Novel Entities,” Environmental Science & Technology 56, no. 3 (2022): 1510 – 1521. The Donut Model describes how economics can accommodate such restraints with minimum harm: Kate Raworth, Doughnut Economics: Seven Ways to Think like a 21st Century Economist (London: Chelsea Green Publishing, 2017).
3. Jeffrey Sachs, Guillaume Lafortune, Christian Kroll, Grayson Fuller, and Finn Woelm, Sustainable Development Report 2022: From Crisis to Sustainable Development: The SDGs as Roadmap to 2030 and Beyond (London: Cambridge University Press, 2022), https://s3.amazonaws.com/sustainabledevelopment.report/2022/2022-sustainable-development-report.pdf.
4. By 2016, humanity had overshot by 168%, according to the Global Footprint Network. The website (https://www.footprintnetwork.org) also offers calculators for individual and national footprints.
5. Van Rensselaer Potter, Global Bioethics: Building on the Leopold Legacy (East Lansing, MI: Michigan State University Press, 1988).
6. A general introduction to human security can be found in Alexander Lautensach and Sabina Lautensach, Human Security in World Affairs: Problems and Opportunities, 2nd edition (Prince George, Canada: University of Northern British Columbia, 2020), available at opentextbc.ca/humansecurity/. The UN’s SDG program represents the dominant view how sustainable human security can be achieved worldwide: United Nations, Sustainable Development Goals: 17 Goals to Transform Our World (New York: UN Department of Public Information, 2015), https://www.un.org/sustainabledevelopment/sustainable-development-goals/.
7. Richard Grossman, “The Importance of Human Population to Sustainability,” Environment, Development, and Sustainability 14, no. 3 (2012): 973–977.
8. Seth Wynes and Kimberly A. Nicholas, “The Climate Mitigation Gap: Education and Government Recommendations Miss the Most Effective Individual Actions,” Environmental Research Letters 12 (2017), https://iopscience.iop.org/article/10.1088/1748-9326/aa7541/pdf.
9. William E. Rees, “The Fractal Biology of Plague and the Future of Civilization,” Journal of Population & Sustainability 5, no. 1 (2020): 3–18, https://www.researchgate.net/publication/347096273.
10. This argument is presented in Chapter 15 in Lautensach and Lautensach, Human Security in World Affairs; also by Rees, “The Fractal Biology of the Plague,” and by Garrett Hardin, “Living on a Lifeboat,” in Contemporary Moral Problems, ed. James White (New York: West Publishing, 1988): 143-156.
11. Hedberg, The Environmental Impact of Overpopulation, 8.
12. Ted Mosquin and Stan Rowe, "A Manifesto for Earth," Biodiversity 5, no. 1 (2004): 3–9, https://www.ecospherics.net/pages/EarthManifesto.pdf.
13. If it is our responsibility to care for animal populations where humans have hampered nature’s capacity to keep them healthy, then our own species deserves the same consideration, argued Lionel Shriver in Game Control (London: Faber & Faber, 1994).