William Vogt was an American ecologist and ornithologist, with a strong interest in both the carrying capacity and population control. He was the author of the best-seller Road to Survival (1948), National Director of the Planned Parenthood Federation of America and secretary of the Conservation Foundation.

Malthusianism is the theory that population growth is potentially exponential, according to the Malthusian growth model, while the growth of the food supply or other resources is linear, which eventually reduces living standards to the point of triggering a population decline. This event, called a Malthusian catastrophe occurs when population growth outpaces agricultural production, causing famine or war, resulting in poverty and depopulation. Such a catastrophe inevitably has the effect of forcing the population to "correct" back to a lower, more easily sustainable level. Malthusianism has been linked to a variety of political and social movements, but almost always refers to advocates of population control.