Earlier in this chapter we described the views of Thomas Malthus, the early-nineteenth-century economist who warned that the pressure of population growth would tend to limit the standard of living. Malthus was right about the past: for around 58 centuries, from the origins of civilization until his own time, limited land supplies effectively prevented any large rise in real incomes per capita. Since then, however, technological progress and rapid accumulation of physical and human capital have allowed the world to defy Malthusian pessimism.

But will this always be the case? Some skeptics have expressed doubt about whether sustainable long-run economic growth is possible—whether it can continue in the face of the limited supply of natural resources and the impact of growth on the environment.