Thomas Malthus believed that

Thomas Malthus believed that population growth would eventually exceed the food supply, leading to decreasing living standards, poverty, and war. His theory was based on the fact that populations grow exponentially while food production increases arithmetically. In other words, people's need for food grows rapidly but the resources to provide it can only increase at a much slower rate. This means that the resources necessary to feed people are harder and harder to come by, leading to misery and suffering. Malthus believed that unless population growth was kept in check, either through food shortages, poverty, or war, disaster would befall every society.