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Society's perfectibility, a prevalent 18th-century notion suggesting human progress and societal improvement, was directly challenged by Thomas Malthus's theory on population. Malthus argued that population growth, if unchecked, would surpass the earth's capacity to provide sustenance, leading to inevitable resource scarcity and societal struggles. This pessimistic view contradicted the optimistic belief in societal advancement and sparked significant debates on economics, politics, and social welfare.