Answer:
Inequality.
Step-by-step explanation:
Thomas Malthus was an scholar who developed a theory about population growth. His theory is called the Malthusian theory. This theory states that the population grows faster than the food supply available and therefore, this trend will eventually lead to catastrophe. The catastrophe occurs when the population is greater than the food supply.
Malthus argued that, in order to avoid catastrophe, people were supposed to deliberately go through population control like birth control and celibacy. He said that war, famine, and diseases (and therefore death) keep population under control and make resources still available.
Roman, as an activist, would like a state of sharing and equality that is in contraposition with Malthus theory. If he and his friend read about Thomas Malthus, they would consider the notion that inequality keeps the population in check.