World population stabilisation through Smithian increasing returns to labour: an update

In light of classical political economists’ ideas (especially Smith and Malthus) and more recent theory of demographic transition, Foley (Econ Lett 68:309–317, 2000) constructed a simple integrated population model, which is then used as an alternative tool to project the stabilising level of world population and income level associated with it. This paper is an update of this line of research using more recent empirical evidence. We find the world still exhibits a strong pattern of Smithian increasing returns to scale and most countries’ populations have been stabilising along a convex income–fertility schedule. Our projections suggest that the world population will stabilise at 11.4 billion with per capita income around $12,595 in constant 2005 USD. Unfortunately, the process of world population stabilisation tends to be accompanied with growing global income equality.