The fundamental premise of Malthus’s essay is that population grows in a geometrical ratio while production of food only follows an arithmetic ratio. In other words, population multiplies exponentially, whereas agricultural yields can only increase in a linear fashion. To justify this point, Malthus uses the example of the United States, where population is seen to double every 25 years due to an abundance of fertile land.

However, given there is a limit to the quantity of land in any country, agricultural production, once all land is used up, can only increase to the extent that technology advances. According to Malthus, even if yields can double with new technology, it is not realistic that this type of growth can be sustained. While the same plot of land may be optimized in 25 years to double its production, it is unfathomable that it would once again double in 50 years, and again in 75 years, yielding eight times the original amount. Unlike population growth, which has been observed to increase exponentially in America, agricultural yields can never increase so fast according to historical data. These two forces considered together means the number of people will always tend to exceed their capacity to sustain themselves.