One of the earliest critics was
David Ricardo. Malthus immediately and correctly recognised it to be an attack on his theory of wages. Ricardo and Malthus debated this in a lengthy personal correspondence. In
Ireland, where applying his thesis, Malthus proposed that "to give full effect to the natural resources of the country a great part of the population should be swept from the soil", there were early refutations. In
Observations on the population and resources of Ireland (1821)
, Whitley Stokes, invoking the advantages mankind derives from "improved industry, improved conveyance, improvements in morals, government and religion", denied that there was a "law of nature" that procreation must outrun the means of subsistence. Ireland's problem was not her "numbers" but her indifferent government. In ''An Inquiry Concerning the Population of Nations containing a Refutation of Mr. Malthus's Essay on Population'' (1818),
George Ensor had developed a similar broadside against Malthusian political economy, arguing that poverty was sustained not by reckless propensity to propagate, but rather by the state's indulgence of the heedless concentration of private wealth. Following the same line of argument,
William Hazlitt (1819) wrote, "Mr Malthus wishes to confound the necessary limits of the produce of the earth with the arbitrary and artificial distribution of that produce by the institutions of society".
Thomas Carlyle dismissed Malthusianism as pessimistic
sophistry. In
Chartism (1839), he denied the possibility that "twenty-four millions" of English "working people[s]", "scattered over a hundred and eighteen thousand square miles of space", could collectively "take a resolution" to diminish the supply of labourers "and act on it". Even if they could, the ongoing influx of Irish immigrants would render their efforts redundant. Associating Malthusianism with
laissez-faire, he instead advocated proactive legislation. His later essay "Indian Meal" (1849) argued that
maize production would remedy the failure of the potato crop as well as any prospective food shortages.
Karl Marx (who had occasion to cite Ensor) referred to Malthusianism as "nothing more than a school-boyish, superficial plagiary of
Defoe, Sir
James Steuart,
Townsend,
Franklin, Wallace". Marx argued, even more broadly, that the growth of both a human population
in toto and the "
relative surplus population" within it, occurred in direct proportion to
accumulation.
Henry George in
Progress and Poverty (1879) criticised Malthus's view that population growth was a cause of poverty, arguing that poverty was caused by the concentration of ownership of land and natural resources. George noted that humans are distinct from other species, because unlike most species humans can use their minds to leverage the reproductive forces of nature to their advantage. He wrote, "Both the hawk and the man eat chickens; but the more hawks, the fewer chickens, while the more men, the more chickens." supported with and without synthetic nitrogen
fertilizers. D. E. C. Eversley observed that Malthus appeared unaware of the extent of
industrialisation, and either ignored or discredited the possibility that it could improve living conditions of the poorer classes.
Barry Commoner believed in
The Closing Circle (1971) that technological progress will eventually reduce the demographic growth and environmental damage created by civilisation. He also opposed coercive measures postulated by neo-malthusian movements of his time arguing that their cost will fall disproportionately on the low-income population who are struggling already.
Ester Boserup suggested that expanding population leads to agricultural intensification and development of more productive and less labor-intensive methods of farming. Thus, human population levels determines agricultural methods, rather than agricultural methods determining population. Environmentalist founder of
Ecomodernism,
Stewart Brand, summarised how the Malthusian predictions of
The Population Bomb and
The Limits to Growth failed to materialise due to radical changes in fertility that peaked at a growth of 2 percent per year in 1963 globally and has since rapidly declined. Short-term trends, even on the scale of decades or centuries, cannot prove or disprove the existence of mechanisms promoting a Malthusian catastrophe over longer periods. That said, critics have pointed to the prosperity of a large part of the human population at the beginning of the 21st century, and the debatability of the predictions for
ecological collapse made by
Paul R. Ehrlich in the 1960s and 1970s. Economist
Julian L. Simon, in
The Ultimate Resource, contends that technology can prevent a Malthusian catastrophe. Medical statistician
Hans Rosling also questioned its inevitability. . They have been rising largely due to effects of the "green revolution". In developing countries maize yields are also still rapidly rising.
Joseph Tainter asserts that science has diminishing marginal returns and that scientific progress is becoming more difficult, harder to achieve, and more costly, which may reduce efficiency of the factors that prevented the Malthusian scenarios from happening in the past. The view that a "breakout" from the Malthusian trap has led to an era of sustained economic growth is explored by "
unified growth theory". One branch of unified growth theory is devoted to the interaction between human evolution and economic development. In particular, Oded Galor and Omer Moav argue that the forces of natural selection during the Malthusian epoch selected beneficial traits to the growth process and this growth enhancing change in the composition of human traits brought about the escape from the Malthusian trap, the demographic transition, and the take-off to modern growth. == See also ==