A century after Malthus lived, another British economist, John Maynard Keynes,
based much of the theory ofKeynesian economics, an approach widely used in
the United States and other developed countries in the 1930s, on Malthusian con-
cepts. The writings of Malthus also had a ready impact on the politics of his own
day, especially regarding the so-called Poor Laws of England, which were
designed to address the poverty generated by the dramatic shifts in employment
and economic development brought about by theagricultural revolution. In addi-
tion, theEssay on the Principle of Populationwas a major stimulus for the imple-
mentation of a regular 10-year census in the United Kingdom, starting in 1801 and
continuing through the present day.
Malthus had many critics in his own time, and his theories remain controversial
today. The periodic Malthusian catastrophes predicted by the theory have failed to
materialize in the economically developed world for the last two centuries. For
example, no country in Western Europe or North America has experienced mas-
sive population losses due to famine, except in isolated cases such as the Irish
Potato Famine of 1847–52, since theEssay on the Principle of Populationwas first
published in 1798. Malthus, writing before the mechanization of agriculture and
accompanying advancements in food production brought about by the Industrial
Revolution, failed to anticipate the massive increases in farm output that would
result from technological innovation. Indeed, in 1800 global population is esti-
mated to have been slightly less than 1 billion people, and by 2008 had reached
almost 7 billion. As modern critics of Malthus point out, according to Malthusian
theory, such an increase would surely trigger a Malthusian catastrophe of global
proportions. In fact, although food shortages occasionally strike many developing
regions, these “positive checks” have had little impact on overall rates of popula-
tion growth. Furthermore, Malthus failed to account for some of the major geo-
graphical and social trends of the 20th century, especially theurbanizationof
populations in North America, Europe, and parts of Asia; and the social advance-
ment of women in education and employment.
In spite of the persistent criticism of Malthusian theory in the 19th and early 20th
centuries, in the 1960s the theory was revived in the form of neo-Malthusianism.
This school of theorists suggested that although the evidence of the cyclical princi-
ple that Malthus had articulated in the early 1800s had not materialized, in fact,
Malthus was accurate in his approach. According to Paul Ehrlich and other leading
proponents of the neo-Malthusian perspective, Malthus had erred only in his timing:
the Industrial Revolution had only postponed the cycle, and humanity was once
again approaching the point where population growth would outstrip food produc-
tion. The benchmark work of the neo-Malthusians was Ehrlich’s 1968 book,The
Population Bomb, which had an immediate effect on social policy and legislation
in the developing world, especially the United States. Ehrlich predicted massive
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