growing population remained a necessary factor in the continuing "progress of society", generally. Modern neo-Malthusians are generally more concerned than Malthus with environmental degradation and catastrophic famine than with poverty. Malthusianism has attracted criticism from diverse schools of thought, including Georgists, Marxists and socialists, libertarians and free market enthusiasts, feminists and human rights advocates, characterising it as excessively pessimistic, misanthropic or inhuman. Many critics believe Malthusianism has been discredited since the publication of Principle of Population, often citing advances in agricultural techniques and modern reductions in human fertility. Some modern proponents believe that the basic concept of population growth eventually outstripping resources is still fundamentally valid, and that positive checks are still likely to occur in humanity's future if no action is taken to intentionally curb population growth. In spite of the variety of criticisms against it, the Malthusian argument remains a major discourse based on which national and international environmental regulations are promoted. History Malthus' theoretical argument In 1798, Thomas Malthus proposed his hypothesis in An Essay on the Principle of Population. He argued that although human populations tend to increase, the happiness of a nation requires a like increase in food production. "The happiness of a country does not depend, absolutely, upon its poverty, or its riches, upon its youth, or its age, upon its being thinly, or fully inhabited, but upon the rapidity with which it is increasing, upon the degree in which the yearly increase of food approaches to the yearly increase of an unrestricted population." However, the propensity for population increase also leads to a natural cycle of abundance and shortages: Malthus faced opposition from economists both during his life and since. A vocal critic several decades later was Friedrich Engels. Early history Malthus was not the first to outline the problems he perceived. The original essay was part of an ongoing intellectual discussion at the end of the 18th century regarding the origins of poverty. Principle of Population was specifically written as a rebuttal to thinkers like William Godwin and the Marquis de Condorcet, and Malthus's own father who believed in the perfectibility of humanity. Malthus believed humanity's ability to reproduce too rapidly doomed efforts at perfection and caused various other problems. His criticism of the working class's tendency to reproduce rapidly, and his belief that this, rather than exploitation by capitalists, led to their poverty, brought widespread criticism of his theory. Malthusians perceived