Cambridge International as and a level Economics Ebook

Malthusian theory: 
the view that population grows in 
geometric progression whereas the quantity of food grows in 
arithmetic progression.
KEY TERM
235
Chapter 9: The macroeconomy 

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Th
e theory suggests that a country’s population has a 
tendency to grow in geometric progression (i.e., 1, 2, 4, 8, 
16, etc.) over time, while food supplies have a tendency to 
increase only in arithmetic progression (i.e., 1, 2, 3, 4, 5, 
etc.). He thought there was this tendency for population 
growth to outstrip food production because the quantity 
of land was in relatively fi xed supply (the fi xed factor) and, 
as increasing quantities of labour (the variable factor) were 
added in production, diminishing returns would set in. 
Malthus thought there were checks that kept population 
to a level sustainable by the available food supplies. 
He divided these checks into positive and preventative 
checks. Positive checks increase the death rate and 
include epidemics, diseases and war. Preventative checks 
reduce the birth rate and include delaying marriage and 
contraception.
Th
e Malthusian theory has, however, been 
challenged on a number of grounds. Th
e main 
weakness is that it fails to recognise the impact of 
changes in technology upon food production and 
distribution. Malthus could not have foreseen the huge 
changes that were to occur in agricultural production, 
such as mechanisation, the application of more eff ective 
fertilisers and insecticides and the introduction of 
new high-yield seeds and genetically modifi ed crops. 
Th
ese changes mean that food supplies have increased 
to a level capable of supporting a much higher level of 
world population.
Nevertheless, malnourishment and famine remain 
problems in some developing economies. Th
ese 
problems arise from a range of factors, including uneven 
distribution of resources in the world, poor management 
of agricultural sectors, vulnerability to sudden supply 
shocks, such as fl oods and drought, and an inability to 
respond to these.
Th
e higher birth rate of developing economies 
results in a relatively low average age of population. Th
is 
creates a high proportion of dependent, non-productive 
members of the population. Th
ey are said to have very 
high