English economist and professor Thomas R. Malthus (1766-1834) caused great public controversy among the optimistic positivitists of his day when his Essay on the Principle of Population (1798) showed incontrovertibly that population, when unchecked, tends to increase faster than the availability of subsistence therefore preventive checks on population increase are necessary. Malthus, whose work influenced the research of Charles Darwin, admitted he was pessimistic about the future of humankind. He argued, through mathematical proofs and scientific documentation, that without population control the societal result is overcrowding, disease, war, poverty, and vice.