Thomas Malthus was an English political economist famous for his Essay on the Principle of Population, published in 1798, in which he argues that unchecked population growth always exceeds the growth of means of subsistence. Actual (checked) population growth is kept in line with food supply growth by "positive checks" (starvation, disease and the like, elevating the death rate) and "preventive checks" (i.e., postponement of marriage, etc., that keep down the birthrate), both of which are characterized by "misery and vice". Malthus was motivated by what he saw as the decline of living conditions in nineteenth century England. He blamed this decline on three elements: the overproduction of young; the inability of resources to keep up with the rising human population; and the irresponsibility of the lower classes. Malthus’ ideas were resurrected in the limits to growth debates of the 1970s in which so-called neo-Malthusians argued that resource depletion and environmental degradation were symptoms of society exceeding its carrying capacity.

Malthus presented to his readers a dystopian, negative view of the world, in contrast to the utopias of writers such as Jean-Jacques Rousseau and William Godwin. Disasters occurring as a consequence of population growth outstripping resources have become known as Malthusian catastrophes.

Malthus became hugely influential, and controversial, in economic, political, social and scientific thought. Many of those whom subsequent centuries sometimes term "evolutionary biologists" read him,  notably Charles Darwin and Alfred Russel Wallace, for each of whom Malthusianism became an intellectual stepping-stone to the idea of natural selection.  Malthus remains a writer of great significance.

Sources

• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2008. "Malthus, Thomas." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth September 15, 2006; Last revised December 1, 2008; Retrieved June 30, 2009]. 
• Wikipedia Contributors, Thomas Robert Malthus, Wikipedia The Free Encyclopedia, Accessed 30 June 2009.