Final answer:
Thomas Malthus observed that populations increase at a faster rate than the food supply and concluded that poverty is unavoidable due to this population growth.
Step-by-step explanation:
Thomas Malthus (1766-1834) was an English economist who observed that populations tend to increase geometrically while food supplies increase only arithmetically. In his book 'An Essay on the Principle of Population,' published in 1798, Malthus concluded that poverty was unavoidable due to the population increasing at a faster rate than the food supply. He believed that war, famine, and disease would control population growth as 'positive checks,' while 'preventive checks' like birth control and celibacy would also work to control population.