An Essay on the Principle of Population

Malthus argued that population grows geometrically while food production grows arithmetically, so population must always press against the limit of subsistence, and that this pressure is checked either by what he called positive checks, meaning famine, disease and war, or by preventive checks, meaning delayed marriage and reduced fertility.

The political purpose of the first edition was to argue against the utopian projections of Godwin and Condorcet, who held that human institutions could be perfected. Malthus argued the population mechanism made this impossible: any improvement in living standards would raise fertility and reduce mortality until subsistence pressure restored the previous condition. He extended this into an argument against the English Poor Laws, contending that relief raised the population of the poor without increasing the food available to them.

The empirical prediction failed. Agricultural productivity grew faster than Malthus allowed, industrialisation raised output per person enormously, and fertility fell as incomes rose rather than rising, which is the demographic transition his model does not contain. The failure is fundamental rather than a matter of timing.

The essay nonetheless matters. It supplied Darwin and Wallace with the mechanism of selection pressure, both of whom credited it directly. It established resource constraint as a category in economics and remains the origin of every subsequent limits-to-growth argument. And the trap it describes did operate for most of human history before the industrial revolution, which economic historians have documented. Read it as a foundational error with enormous consequences.