English economist and social scientist. His fame rested on what was in effect a long pamphlet, An Essay on the Principle of Population, As It Affects the Future Improvement of Society (1798), in which he observed that the growth of population is ultimately limited by the food supply. He supported this common thesis with the metaphor that population, when allowed to increase without limit, increases in a geometrical ratio, while the food supply can at best increase in an arithmetical ratio; so, whatever the plausible rate of increase of the food supply, an unchecked multiplication of human beings could be disastrous. But the powerful impact of the Essay derived as much from its stark implications as from the thesis itself. Poverty had its roots, not in social and political institutions, but in the unequal race between population and the food supply. Nothing could stem the tide of numbers except the voluntary limitation of family size by the poor themselves. Thus, at one stroke, Malthus…