2.6 Malthusian Theory

Malthus's core argument

In 1798, Thomas Malthus argued that human population grows geometrically (1, 2, 4, 8...) while food supply grows arithmetically (1, 2, 3, 4...). He predicted population would eventually outpace food production, leading to famine, disease, and war as natural checks that limit population growth back to sustainable levels.

Neo-Malthusians and critics

Neo-Malthusians update the theory, warning about resource depletion, environmental degradation, and climate change limiting carrying capacity. Critics point to the Green Revolution, technology, and agricultural innovation, which massively increased food production beyond what Malthus predicted, showing his model underestimated human ingenuism and technological adaptation.

Checks on population

Malthus identified positive checks (famine, disease, war — factors that increase the death rate) and preventive checks (delayed marriage, abstinence — factors that reduce birth rate). Modern critics also note Malthus didn't foresee contraception, global trade of food, and demographic transition patterns that lower birth rates as societies develop.

Key terms

Malthusian Theory

Thomas Malthus's 1798 theory that population grows geometrically while food supply grows arithmetically, leading to eventual food shortages.

Positive checks

Factors that increase the death rate to limit population, such as famine, disease, and war.

Preventive checks

Factors that reduce the birth rate to limit population, such as delayed marriage and abstinence.

Neo-Malthusians

Modern theorists who apply Malthus's ideas to concerns like resource depletion, overpopulation, and environmental degradation.

Green Revolution (as critique of Malthus)

Agricultural advancements that vastly increased food production, undermining Malthus's prediction of inevitable famine.

Try an AP-style question

Malthus predicted that population grows…

1. geometrically while food grows arithmetically
2. arithmetically while food grows geometrically
3. at the same rate as food
4. only in cities