The Vicious Cycle between Demography and War

Brezis, Elise (2025): The Vicious Cycle between Demography and War.

Abstract

This paper highlights a vicious circle between demography and war. Countries face the choice between two possible equilibria. The first equilibrium is characterized by high fertility rates, a predominantly young population with a low median age, and a high risk of conflict. In contrast, the second equilibrium is marked by low fertility rates, higher life expectancy, an aging population, and no youth bulge which increase the probability of conflict and war. The data emphasize that countries with high fertility rates, above five children per woman, face a 75% likelihood of experiencing conflict. In contrast, countries with fertility rates below two exhibit less than an 8% probability of conflict. This paper presents a new framework in which fertility rates and the probability of conflict are endogenously determined, leading to multiple equilibrium outcomes. The core idea is that high fertility rates increase the likelihood of conflict due to the "youth bulge" phenomenon. Conversely, war and conflict—by causing high mortality among soldiers—motivate families to increase their birth rates. This reciprocal dynamic results in multiple possible equilibria. As a result, the world faces regional disparities in conflict and population growth. On the one hand, there are countries characterized by low fertility rates, an aging population, and high capital stock, which experience low conflict probabilities. In contrast, there are regions such as parts of Africa and the Middle East, with high fertility rates and younger populations, which are more prone to conflict.

• Item Type: MPRA Paper
• Language: English
• Keywords: aging population, war, conflicts, median age, fertility rates, youth bulge
• Subjects: D - Microeconomics > D7 - Analysis of Collective Decision-Making > D74 - Conflict ; Conflict Resolution ; Alliances ; Revolutions; J - Labor and Demographic Economics > J1 - Demographic Economics > J13 - Fertility ; Family Planning ; Child Care ; Children ; Youth; J - Labor and Demographic Economics > J1 - Demographic Economics > J14 - Economics of the Elderly ; Economics of the Handicapped ; Non-Labor Market Discrimination; O - Economic Development, Innovation, Technological Change, and Growth > O4 - Economic Growth and Aggregate Productivity > O40 - General

References

Ang, J. B., and Madsen, J. B. 2015. "Imitation versus innovation in an aging society: international evidence since 1870". Journal of Population Economics, 28(2), 299–327.

Baxter Simon 1989. "Gender and violent crimes" in: Violent Crime, Violent Criminals (Wolfgang ME, Weiner NA, eds). London: Sage

Aaby, P. 1988. "Malnutrition and overcrowding/intensive exposure in severe measles infection: Review of community studies". Review of Infectious Diseases 10: 478-491.

Baland, Jean-Marie and James A. Robinson. 2000. "Is child labor inefficient?" Journal of Political Economy 108, 663–679.

Barro, Robert J. and Gary S. Becker. 1989. "Fertility choice in a model of economic growth". Econometrica 57, 481–501.

Becker, G.S., 1968. "Crime and Punishment: An economic approach", Journal of Political Economy, p. 169-217.

Becker, Gary S. 1960. An economic analysis of fertility. In Demographic and Economic Change in Developed Countries, pp. 209–231. Princeton

Becker, Gary S., Kevin M. Murphy, and Robert Tamura 1990. "Human capital, fertility and economic growth". Journal of Political Economy 98, S12–S37.

Bénassy, J-P, and E S. Brezis. 2013. “Brain Drain and Development Traps.” Journal of Development Economics 102: 15–22.

Bloom, David E., David Canning, and Günther Fink. 2011 "Implications of Population Aging for Economic Growth." NBER working paper 16705.

Brezis, E.S. and P. Krugman. 1997. "Technology and Life Cycle of Cities”, Journal of Economic Growth, 369-383.

Brezis, E.S. and P. Krugman. 1993. "Leapfrogging in International Competition: A Theory of Cycles in National Technological Leadership.” American Economic Review, 1211-1219.

Brezis, E. S., and Ferreira, R. D. S. 2016. "Endogenous Fertility With A Sibship Size Effect". Macroeconomic Dynamics, 20(8), 2046–2066.

Brezis, E.S. and W. Young. 2003. "The new views on demographic transition: a reassessment of Malthus's and Marx's approach to population", European Journal of the History of Economic Thought 10: 25-45.

Brezis, E.S., and Thierry Verdier 2012. “Non-Linear Geographics and the Economics of Transition and Democratization” Economics of Transition, (3):1-19.

Brezis, E. 2010. "Can Demographic Transition only be Explained by Altruistic and Neo-Malthusian Models?", Journal of SocioEconomics, (39): 233-240.

Brezis, E. 2001 “Social Classes, Demographic Transition and Economic Growth”, European Economic Review, 45: 707-717.

Brooks, D. B, S. G. Brooks, B. D. Greenhill, and M. L. Haas. 2018. "The Demographic Transition Theory of War: Why Young Societies Are Conflict Prone and Old Societies Are the Most Peaceful", International Security" 43(3), pp. 53-95.

Charbit, Y. 2009. Economic. Social and demographic thought in the XIXth century: the population debate from Malthus to Marx. London and NY: Springer.

Choucri, Nazli. 1974. Population dynamics and international violence: insights and evidence. Lexington, MA: Lexington.

Cincotta, Richard P., Robert Engelman, and Daniele Anastasion. 2003. "The Security Demographic: Population and Civil Conflict After the Cold War." Washington, DC: Population Action International.

Cincotta R. and Hannes Weber. 2021. "Youthful Age Structures and the Risks of Revolutionary and Separatist Conflicts". in Global Political Demography: The Politics of Population Change edited by Achim Goerres and Pieter Vanhuysse . Palgrave

Cincotta, Richard. 2023. "Population Age Structure and the Vulnerability of States to Coups d’État" The journal Statistics, Politics and Policy.

Collier, Paul. 2000. "Doing well out of war: An economic perspective" . In Greed and grievance: Economic agendas in Civil Wars: edited by Mats Berdal and David M. Malone. Boulder, Co and London

Collier, Paul and Anke Hoeffler. 1998. " On Economic Causes of Civil War ". Oxford Economic Papers, vol. 50, 563–573.

Collier, Paul and Anke Hoeffler. 2004. "Greed and Grievance in Civil War". Oxford Economic Papers, vol. 56, pp. 563–595.

Desai, S. 1995. When are children from large families disadvantaged? Evidence from cross-national analyses”. Population Studies 49: 195-210.

Frosch, K. H. 2011. "Workforce age and innovation: A literature survey". International Journal of Management Reviews, 13(4): 414–430

Fuller G, Pitts FR. 1990. "Youth Cohorts and Political Unrest in South Korea". Political Geography Quarterly 9(1): 9-22.

Fuller G. 1995. "The Demographic Backdrop to Ethnic Conflict: A Geographic Overview", in: The Challenge of Ethnic Conflict to National and International Order

Goldstone, Jack A. 2010. "The New Population Bomb: The Four Megatrends That Will Change the World." Foreign Affairs 89, no. 1: 31-43.

Goldstone, Jack A. 2002. "Population and Security: How Demographic change can lead to violent conflict" Journal of International Affairs

Goldstone, Jack A. 1991. Revolution and Rebellion in the Early Modern World. Berkeley, CA: University of California Press.

Goldstein, Joshua S. 2004. War and gender. New York: Springer US

Huntington, Samuel P. 1996. The clash of civilizations and the remaking of world order. New York: Simon & Schuster.

Heinsohn, Gunnar. 2003 Söhne und Weltmacht: Terror im Aufstieg und Fall der Nationen

Jackson, Richard, and Neil Howe. 2008. The Graying of the Great Powers: Demography and Geopolitics in the 21st Century. Washington, DC: Center for Strategic and International Studies.

Krugman, P., 1991. History vs. expectations. Quarterly Journal of Economics 106, 651–667.

Lee, R. and A. Mason. 2014. "Is Low Fertility Really a Problem? Population Aging, Dependency, and Consumption Science" 346: 229–234.

Malthus, T.R. 1970. An Essay on the Principle of Population. London: Penguin Books.

Marx, K. 1967 and 1976. Capital, Vol. I. Vol II. New York: International Publishers.

Marx, K. and F. Engels. 1955. The Communist Manifesto. New York: Appleton-Century-Crofts.

Mesquida CG, Wiener NI. 1996. "Human Collective Aggression: a Behavioral Ecology Perspective". Ethology and Sociology 17: 247-262

Mesquida CG, Wiener NE. 1999. "Male Age Composition and the Severity of Conflicts". Politics in the Life Sciences 18(2): 181-189

Moller, Herbert. 1968. "Youth as a force in the modern world". Comparative Studies in Society and History, vol. 10, pp. 238–260.

Murphy, Kevin M, Andrei Shleifer, and Robert W Vishny. 1989. “Industrialization and the Big Push.” Journal of Political Economy 97 (5): 1003-1026.

National Intelligence Council. 2012. Global Trends 2030: Alternative Worlds. Office of National Intelligence.

Neumayer, E. 2003. "Good Policy Can Lower Violent Crime: Evidence from a Cross-National Panel of Homicide Rates, 1980–97". Journal of Peace Research, 40(6), 619-640

Ruiu, Gabriel, Marco Breschi and Alessio Fornasin. 2023. "The older, the wiser and also the less innovative? An empirical analysis of the relationship between population aging and innovativeness", International Journal of Population Studies 9.2: 429.

Ruiu, Gabriel, Marco Breschi. 2019. "The effect of aging on the innovative behavior of entrepreneurs", Journal of the Knowledge Economy. 10.4: 1784-1807

Strauss, E. 2007. "Factors effecting health behavior, related to breast cancer screening, among Jewish ultra-orthodox women in comparison to Jewish non ultra-orthodox women" Sackler Faculty of Medicine, Tel Aviv University

Taha, W. et. Al. 2001. "Reduced spinal bone mineral density in adolescents of an ultra-orthodox Jewish community in Brooklyn". Pediatrics 107 (5), e-79.

Urdal, Henrik. 2005. Population and Civil Conflict

Urdal, Henrik. 2006. "A Clash of Generations? Youth Bulges and Political Violence." International Studies Quarterly 50, no. 3: 607-629 . Urdal, Henrik. 2004. The devil in the demographics Social Development paper

Wiltgen, R. 1981. "Marx and Engels on Malthus and population: a reconstruction and reconsideration". Quarterly Review of Economics and Business 21: 107-26.

Wright, C. et. Al. 2010. "Undernutrition in British Haredi infants in the Gateshead millennium cohort study". Archives of Disease in Childhood 95: 630-633.

Zakaria, Fareed. 2001. "The Roots of Rage". Newsweek, vol. 138, No. 16, pp. 14–33.

Zakaria F. 2003. The Future of Freedom. New York: W.W Norton.