Some blame overpopulation for many of the world’s problems such as poverty, famine and war (which are obviously rights violations). There are supposed to be too many people for peaceful coexistence and sustainable food production. Those who worry about overpopulation are often called (neo-)Malthusians, and either predict a sharp fall in population levels because of the problems caused by overpopulation (a “Malthusian catastrophe”), or/and propose population control as a measure to solve these problems.
For pretty much all of human history, population growth constrained growth in real standards of living. That’s the “Malthusian Trap”: as standards of living improved, population increased, which put a strain on resources and drove down standards of living, which in turn drove down population growth, rinse & repeat. The industrial revolution broke this trap, although it’s worth pointing out the fairly obvious fact that this is not true for the entire world. Conor Clarke (source)
What the figure above shows is that over a roughly 3000 year period, during which there was obviously quite a lot of technological progress — iron plows, horse collars, mastering the cultivation of rice, the importation of potatoes into Europe, etc. — living standards basically went nowhere. Why? Because population growth always ate up the gains, pushing living standards back to roughly subsistence.
The figure [below] helps suggest why: technological change was slow — so slow that by 1600 or so, when England had finally reclaimed its population losses from the Black Death, it found real wages back to more or less 1300 levels again.
And here’s the sense in which Malthus was right: he had a fundamentally valid model of the pre-Industrial Revolution economy, which was one in which technological progress translated into more people, not higher living standards. This homeostasis only broke down when very rapid technological change finally outstripped population pressure for an extended period. Paul Krugman (source)
It’s apparent from this last graph that population growth can go hand in hand with income growth, and that it’s not correct to state that population growth necessarily leads to more poverty, which in turn leads to a reversal of population growth. But these compatible evolutions of population and income seem to require technological advances.
Note: my criticism of Malthusianism and other types of overpopulation hysteria (see here for some examples) is targeted only at deterministic theories which believe in overpopulation as the main if not only cause for the world’s problems, and which see overpopulation as a global problem. I accept that in certain specific areas of the world, population pressures can make things worse. But I don’t agree that these pressures are the sole or even the main cause of problems such as poverty, famine, war etc. And neither do I agree that population control is the main remedy for these problems. For example, we all know that water shortages – even very local ones – aren’t caused by overpopulation and won’t be solved by population control. More intelligent irrigation methods are the answer. And when we leave the local level and take the global point of view, the population problem is even less salient. On a world scale, income has grown systematically faster than the world’s population during the last centuries. Population pressures do not lead us to an inevitable “trap” as Malthus and his followers claim.