Malthusian Limit

Thomas Malthus was an English economist in the 1700s. He pointed out that there are two critical variables when discussing humankind:

• The current population and its rate of growth, which is exponential (more humans leads to more humans; 1, 2, 4, 8, 16, 32)

• The current rate of food production and its rate of growth, which is linear (1, 2, 3, 4, 5, 6).

Malthus posited that there was therefore a “limit” on the population that the planet could support. As population growth would near the limits of food production, various consequences would occur – famine, poverty, disease, etc. – that would cause the rate population growth to back off.

Population growth was therefore limited by the slower growth of food production, and it would hover around this limit – moving past it, then moving back, etc.

In general terms, “a Malthusian limit” might refer to two variables, one of which is limited by the other.

For example, we would often joke in my household that the family’s happiness was limited by our daughter’s happiness. Everyone could only be as happy as she was – if she wasn’t very happy, no one else would be either. So, it might be said that her level of happiness was a Malthusian limit on the level of happiness of the rest of the family.

(Although, I don’t know that I’ve heard of the phrase being used in a general context. I just feel like I’ve heard it too many times for it to always be referring to the original concept, which is quite specific.)

A critical question is: is the Malthusian limit true? Does it actually exist? Many have said no, because Malthus didn’t take into account technological “leaps” in food production, such as the Haber-Bosch Process, which break the linearity of it. (See The Structure of Scientific Revolutions for more on scientific “lurches.”)