2014 : WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT?

T. Robert Malthus (he used his middle name) thought population must outstrip food supply and "therefore we should facilitate, instead of foolishly and vainly endeavouring to impede," disease, hunger and war. We should "court the return of the plague" and "particularly encourage settlements in all marshy and unwholesome situations". This nasty idea—that you had to be cruel to be kind to prevent population growing too fast for food supply—directly influenced heartless policy in colonial Ireland, British India, imperial Germany, eugenic California, Nazi Europe, Lyndon Johnson's aid to India and Deng Xiaoping's China. It was encountering a Malthusian tract, The Limits to Growth, that led Song Jian to recommend a one-child policy to Deng. The Malthusian misanthropic itch is still around and far too common in science.

Yet Malthus and his followers were wrong, wrong, wrong. Not just because they were unlucky that the world turned out nicer than they thought; that keeping babies alive proved a better way of getting birth rates down than encouraging them to die; not just because technology came to the rescue; but because Malthusians have repeatedly made the mistake of thinking of resources as static, finite things that would "run out". They thought growth meant using up a fixed heap of land, metals, water, nitrogen, phosphate, oil, and so forth. They thought the birth of a calf was a good thing because it added to the world's resources, but the birth of a baby was a bad thing because it added to the mouths to feed.

This completely misunderstood the nature of a resource, which only becomes a resource thanks to human ingenuity. So uranium oxide is not a resource before nuclear power. Shale oil was not a resource till horizontal fracking. Steel was not easily recyclable till the electric-arc furnace. Nitrogen in the air was not a resource till the Haber process. The productivity of land was transformed by fertiliser so globally we now use 65% less land to produce the same amount of food as 50 years ago. And a baby is a resource too: a brain as well as a mouth.

The few economists, such as Julian Simon and Bjorn Lomborg, who tried to point this out to the Malthusian scientists, and who argued that economic growth was not the cumulative use of resources but the increase of productivity—doing more with less—were called imbeciles or had pies thrown in their faces for their trouble. But they were right again and again, as population and prosperity grew together to levels that the Malthusians kept saying were impossible.

"It is unrealistic to suppose that there will be increases in agricultural production adequate to meet forecast demands for food, said a long list of scientific stars in a British book called A Blueprint for Survival in 1972. "Farmers can no longer keep up with rising demand for food and famine is inevitable," said Lester Brown in 1974. (World food production has since doubled and famine is largely history—except where dictators create it).

World population will almost certainly cease to grow before the end of the century; peak farmland is very close if not already past; electric cars driven by nuclear power stations are to all intents and purposes an infinite resource. The world is a dynamic, reflexive place in which change is all. Time to retire the static mistakes of misanthropic, myopic, mathematical Parson Malthus because he never was and never will be right.