Why Malthus makes for bad science policy

If by fiat I had to identify the most consequential ideas in the history of science, good and bad, in the top 10 would be the 1798 treatise An Essay on the Principle of Population by English political economist Thomas Robert Malthus. On the positive side of the ledger, it inspired Charles Darwin and Alfred Russel Wallace to work out the mechanics of natural selection based on Malthus’s observation that populations tend to increase geometrically (2, 4, 8, 16…), whereas food reserves grow arithmetically (2, 3, 4, 5…), leading to competition for scarce resources and differential reproductive success, the driver of evolution.

On the negative side of the ledger are the policies derived from the belief in the inevitability of a Malthusian collapse. “The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race,” Malthus gloomily predicted. His scenario influenced policy makers to embrace social Darwinism and eugenics, resulting in draconian measures to restrict particular populations’ family size, including forced sterilizations.

In his book The Evolution of Everything (Harper, 2015), evolutionary biologist and journalist Matt Ridley sums up the policy succinctly: “Better to be cruel to be kind.” The belief that “those in power knew best what was good for the vulnerable and weak” led directly to legal actions based on questionable Malthusian science. For example, the English Poor Law implemented by Queen Elizabeth I in 1601 to provide food to the poor was severely curtailed by the Poor Law Amendment Act of 1834, based on Malthusian reasoning that helping the poor only encourages them to have more children and thereby exacerbate poverty. The British government had a similar Malthusian attitude during the Irish potato famine of the 1840s, Ridley notes, reasoning that famine, in the words of Assistant Secretary to the Treasury Charles Trevelyan, was an “effective mechanism for reducing surplus population.” A few decades later Francis Galton advocated marriage between the fittest individuals (“What nature does blindly, slowly, and ruthlessly man may do providently, quickly and kindly”), followed by a number of prominent socialists such as Sidney and Beatrice Webb, George Bernard Shaw, Havelock Ellis and H. G. Wells, who openly championed eugenics as a tool of social engineering. (continue reading…)