In a 2022 column, The New York Times’ Ezra Klein wrote of the countless people he meets who ruminate about whether to have children ‘given the climate crisis they will face… [and] knowing they will contribute to the climate crisis.’ Klein’s acquaintances are not an anomaly. He cited survey data suggesting that a quarter of childless adults believe climate change is a reason to avoid reproducing. A 2021 BBC report further backs this up, highlighting global survey data indicating ‘climate anxiety’ is a commonly given reason for not having kids.
The people Klein describes remind me of the early 19th-century English cleric Thomas R. Malthus. Malthus remains famous for sounding the alarm on overpopulation. Though his views became considerably milder and more nuanced over time, he is most remembered for his earliest model of population growth.
Malthus claimed that population increases geometrically, but the ‘necessaries of life’, like food, increase only arithmetically. The result: the population level tends to surpass material sustenance, leading to famine, starvation and population decline.
Similar to Malthus’ early views, contemporary anti-natalists believe that additional human beings pose a threat to the environment and to already-existing human beings.
What such views tend to miss is an insight that the father of modern economics Adam Smith already understood in the eighteenth century: the potential for innovation to outpace population growth.
Smith was bullish about the prospects of technological improvement and innovation. He favored economic liberalisation and seems to have seen population growth as an indicator of success. As Maria Pia Paganelli has argued, Smith used population in ‘The Wealth of Nations’ as a proxy for material betterment, analogous to how we now use Gross Domestic Product. When Smith expounded on the negative effects of trade restrictions, he noted their tendency to reduce population.
Anti-natalists past and present have tended to speak as if resources are relatively fixed. In doing so, they overlook the possibility of new discoveries and increasing returns to scale. Malthus, for example, believed that population size would outstrip the food supply because land is limited and farming experiences decreasing returns to scale.
Smith, by contrast, seems to have been of the view that productivity did not face an enduring upper bound, but rather could be expanded upwards through innovation and economic growth.
He was especially bullish about the prospects for agricultural innovation. Smith reflected on the arrival of the potato to Europe. Compared to wheat, potato cultivation meant that ‘[T]he same quantity of cultivated land would maintain a much greater number of people.’ Smith likewise predicted ‘population would increase’ if potato cultivation became at least as common as wheat cultivation. In 2011, economists Nathan Nunn and Nancy Qian estimated that ‘the introduction of the potato explains 25–26 percent of the increase in Old World population between 1700 and 1900.’
In ‘The Wealth of Nations’, Smith argued ‘that the Division of Labour is limited by the Extent of the Market’ and that ‘the extent of [a country’s] market… must for a long time be in proportion to the populousness of that country’. In other words, a larger population enables a greater division of labour. A greater division of labour yields increased specialisation along with new machines and new methods. Productivity rises. Smith saw human beings as not only a consequence of economic growth but as a potential cause.
It is true that more people increase the demand for goods and services – thereby increasing scarcity and provoking price rises. But Smith appears to have believed that the long-run supply curve slopes downwards. In the presence of freedom and the profit motive, more people create an incentive for new discoveries. Consider what Smith says in ‘The Wealth of Nations’:
The increase of demand, besides, though in the beginning it may sometimes raise the price of goods, never fails to lower it in the long run. It encourages production, and thereby increases the competition of the producers, who, in order to undersell one another, have recourse to new divisions of labour and new improvements of art, which might never otherwise have been thought of.
Finding more efficient substitutes and using smaller and smaller units of a given resource to produce greater levels of output are some of the defining developments of the last 300 years. World population in 1700 was about 600 million people. Today, we are more than ten times that, at about 8 billion. Meanwhile, we have both a higher quantity and a higher quality of food than ever before. And contrary to popular belief, in many respects the planet is cleaner than ever before (e.g., sanitation).
Adam Smith foresaw the dynamic ability of free people and free markets. And more specifically, he foresaw the power of human ingenuity within liberalised markets to provide for an increasing population. More human beings are not merely eaters but both an invitation to and a means of raising living standards for all.
In a world of declining fertility, it is remarkable that many still worry about overpopulation. But as the history of the last 250 years suggests, Smith was right all along. We need not fear too many human beings. We can and have found ways to innovate when faced with challenges. Far from being a curse, ‘the multiplication of the species,’ as Smith put it, is a blessing.
This essay is adapted from a longer piece published at AdamSmithWorks.
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