Paul Ehrlich, Estimated Prophet: The modern Malthusian had conviction, if nothing else. (Theodore Dalrymple, Mar 22, 2026, American Conservatism)
Karl Marx detested Malthus, seeing in him an apologist of inescapable mass poverty, but he was much influenced by him nevertheless (as was Darwin), and made precisely the same mistake that Malthus made. Malthus thought that only one variable, the size of population, would change, and did not realize that the productive capacity of the land and industry could more than compensate for the growth in population. Marx did not see this either: He thought the majority of the population was destined for immiseration, leading eventually to a cataclysm, after which everything would be all right.
Ehrlich was a Malthusian; and the problem with Malthusianism is that, however many times you expel it from your thoughts, it returns.
Darwinism, Marxism, Nazism, etc. all flow from the initial nonsense of Malthus.