“Demography is destiny” is a well-known expression. It suggests change is inexorable, somehow unchangeable, subject only to inertia. But demography can be fast.
It is said that demographers have an “easy” job forecasting, especially compared to, say, economists. This is not true, however, especially at the national and sub-national level. Changes in world populations depend only on future births and deaths. At the national level, migration figures in, and crucially so. Take Europe in particular, where fertility and mortality are both low and stable, yet migration – as we have seen – is very hard to predict. The idea of “inertia” does not help us at all.
Not only migrations can change fast. Baby booms (and busts) and sudden policy changes have changed the number of births in the past. Even mortality can change quickly, and not only for the worse like we see in wars.
Yet censuses continue to be spaced ten years apart, meaning they miss many of these fast changes. Monitoring population change requires continuous attention and flows of data. In other words, if we are to capture fast demography, we need data just as fast as the economists.
Francesco C. Billari, Department of Policy Analysis and Public Management, Bocconi University, Milan, Italy.