“Our numbers are burdensome to the world, which can hardly support us … pestilence, and famine, and wars, and earthquakes have to be regarded as a remedy for nations, as the means of pruning the luxuriance of the human race.”

If you were trying to guess the author of that quotation and you chose the 19th century English economist, parson and misanthrope Robert Malthus, it was a good guess. But wrong. The words were actually those of the second century CE theologian Tertullian (thank you, Wikipedia).

I was moved to look up the history of “overpopulation” in response to efforts to give new legs to the crippled liberal hobby horse that “too many people” are the basic cause of environmental problems, including climate change.

The US liberal website Truthout, which I often visit for informative articles about US and international economic, social and political problems – if not often practical ideas on how to overcome them – recently ran a major article by one of its staff reporters, arguing that “addressing population growth” is “crucial” to combating human-caused climate disruption. I think that would be a disastrous diversion for the movement to save our planet.

The Truthout writer is aware that “Very often, arguments about overpopulation are used in defense of racist, sexist, classist and even genocidal policies ...”, and he of course wants to avoid association with such policies. But good motives don’t end the matter. It isn’t enough to call climate change a “population-related problem”. It is also necessary to have a realistic understanding of where, when and why overpopulation exists.

Changing limits

The human population of the world today is around 7.2 billion. When Tertullian wrote that only wars and earthquakes could restrain the “luxuriance” of human numbers, the total was less than 200 million. When Malthus warned that the population would soon outgrow its food supply, the human race totalled about 1 billion people.

We can assume that Tertullian wasn’t making things up: in his day, the human population was pressing on the resources available to maintain it, at least in the Roman Empire, where Tertullian lived. Malthus, to see overpopulation, had only to look around at England’s impoverished landless peasants and workers who could barely survive on their wages.

This indicates that overpopulation is not a fixed magnitude, like the number of protons in an oxygen atom. The size of the human population that the planet can support changes because it is largely determined by the population’s social and scientific-technological development.

In Tertullian’s day, the main limit that population was pushing up against was the low level of humanity’s ability to produce the things it needed. Sixteen hundred years later, productive capacity had increased considerably, and was about to increase even more, so Malthus was behind the times in saying that population threatened to outstrip food production.

But, when Malthus wrote, a new creator of overpopulation had come into existence: capitalism. Capitalism’s development of science and technology increased productivity, and so made a larger human population possible. But the social arrangements necessary to capitalism also require making people “redundant” – that is, surplus, overpopulated.

Karl Marx, in Volume 1 of his great work Capital (chapter 25, sections 3 and 4), explained the paradox that capitalism both requires a constantly increasing population and just as constantly makes large parts of that increased population “surplus”.

‘Surplus’ in capitalism

In periods of economic expansion, the capitalists need to enlarge their workforce massively and quickly. But in their competition for market share, or when the economy slumps, capitalists are compelled to reduce costs by sacking workers or replacing them with machinery.

These pushes and pulls upon workers create what Marx called the “industrial reserve army”: a section of the population, with many heterogeneous layers, who can supply an increased workforce when capital requires it, but who can be pushed out of sight and out of mind – made surplus – whenever economic downturn or technological progress makes them temporarily unneeded.

The tendency of capitalist development is constantly to increase that surplus population: “… capitalistic accumulation itself … constantly produces … in the direct ratio of its own energy and extent, a relatively redundant population of labourers, i.e., a population of greater extent than suffices for the average needs of the self-expansion of capital, and therefore a surplus-population”.

Marx’s analysis in Capital was based primarily on England, at the time the world’s most developed capitalist country. A century and a half later, it is striking to see how well his explanation of capitalist overpopulation in England fits the world capitalist system today.

While an industrial reserve army certainly exists in Australia and other developed capitalist countries, the international spread of capitalism has concentrated the worst excesses of overpopulation in especially underdeveloped regions, such as sub-Saharan Africa and parts of Asia. Parts of the world industrial reserve army are pulled into and out of the international workforce in much the same way as, in Marx’s day, they were drawn into and expelled from the English factory system.

This is not a matter of too many people. It is well known that the world produces more than enough food to feed the entire human population adequately. People starve because capitalism treats people who aren’t currently producing profits for it as surplus, as overpopulation.

Overpopulation, Marx pointed out, differs with different social arrangements: “[E]very special historic mode of production has its own special laws of population.” To apply that understanding to a concrete example today: the Truthout article is concerned, as we all should be, with the shrinking of fresh water supplies in many parts of the world. But capitalist plans for fracking oil in Australia, the US and elsewhere, consuming huge quantities of water and threatening to make large areas uninhabitable by polluting underground aquifers, are caused entirely by pursuit of profit; they would be just as powerful and dangerous if the world’s population were only a half or a third of its present level.

Modern overpopulation is caused by capitalism. If the environmental movement were to focus on curbing population rather than curbing capitalism, it would doom itself to defeat. Saving the planet means saving it for people too – all of them.