This week will see the world’s population reach the 7 billion mark. Not surprisingly, the occasion has excited many declarations from population-control advocates, warning of the danger to us all should such growth continue.
Now, the theory of Thomas Malthus has been used as the scientific justification for anti-human policies from his own time down to the present. But is it true? On the surface, the idea that the more people there are, the less there will be to go around appears to make sense. It therefore follows that if we get rid of some people (especially those we don’t like, anyway), we’ll all be better off. Thus, those interested in eliminating Indians, Irish, Jews, Slavs, Africans, or whomever have been able to argue that their policies, while harsh, are simply necessary to make the world a better place.
Few lies told in the course of human history have been as pernicious, or as false. A look at historical data on the relationships between population growth and living standards demonstrates that the theory of Malthus is at complete variance with the facts.
Let’s begin with Fig. 1, which shows data for world population, global gross domestic product (GDP), and GDP per capita from the year 1 AD down to the year 2000.
Fig. 1 Growth of world population, global GDP, and GDP per capita, from 1 AD to 2000. Note the logarithmic scale. Sources: global GDP (1, 2), world population (1, 2)
This first chart shows that, while human population has certainly increased over time, GDP has increased even more, and the key metric of average human well-being, GDP per capita, has gone up as population has increased, rather than down, as Malthusian theory would predict.
The next chart takes a closer look at the most relevant period — that since the unification of the world economy by the development of long-distance sailing ships around the year 1500.
Fig. 2: Comparison of Malthusian predictions with reality, 1500 to present
In Figure 2, the actual per capita GDP is shown by the thick black line marked with squares. The predictions provided by Malthusian theory, at the time of Malthus’s writing circa the year 1800, are shown with the thin line marked with yellow triangles. According to Malthus, the six-fold increase in population after his time should have resulted in a disastrous drop in human living standards. Instead, global per capita GDP actually increased almost forty-fold, from $179 annually in 1800 to $6,757 by 2000. In short, Malthus was wrong.
Well, everyone has the right to be wrong about predicting the future. But the reader will note that I have taken the liberty of extending Malthus’s prediction into his past. The world population in 1500 comprised 500 million people, just half of that prevailing in Malthus’s day. If living standards go down with increased population, they should go up with decreased population. Thus, according to Malthusian theory, the world should have been much richer in 1500 than it was in 1800, with per capita GDP in the range of $360, instead of the $114 it actually was. Thus Malthus was not just wrong about predicting the future, he was wrong about predicting the past, and not by a small variance, but by a factor of three.