What is the big idea? The big idea is fundamentally a Malthusian view that there are a fixed amount of resources in the world and hence a larger population must, near by necessity, imply dividing the same pie across a larger population and hence make people worse off. I think this idea is fundamentally wrong as it ignores that human beings make choices and respond to their own life and conditions and hence outcomes are all “endogenous” and hence both the size of the pie and the size of the population are the result of both individual choices and evolving and changing social institutions. The historical fact is that the human population has expanded massively and rapidly–and that same historical period is the period of far and away the most rapid progress in every dimension of material well-being–including the impact of the natural environment on human beings. I strongly suspect the historical (if not current) appeal of Malthusian ideas is strongly tied to racist and “eugenic” ideas–the ideas common to the upper classes and castes that it is not so much how many children are being born but that they are being born to the “wrong sort” of people that is the concern (ideas I strongly reject). I have written a bit on this, but never really had sufficient time to turn this into publications.
“Where in the world is population growth bad?” (with Jeff Kling). In this paper we show that, on average, the correlation between population growth and economic growth per capita is very weak, but look whether population growth is harmful in some places (e.g. places with dense population, low resource endowments) but not in others. We are not successful in showing any particular useful correlations, in part because simple ideas like that “overpopulation” in the sense of a large population on a low natural resource base actually doesn’t make any sense for highly successful places/countries like Singapore and Hong Kong. Moreover, countries like Korea responded to the pressures of population and lack of abundant natural resources in the 1960s by looking to succeed in low-wage export industries which led, in that instance, to sustained rapid growth.
Boom Towns and Ghost Countries: Geography, Agglomeration, and Population Mobility. The key idea of this paper is that in the discussion of a “population crisis,” in the sense of there being too little to sustain a population at a decent standard of living people almost exclusively focused on the growth of population, rather than on the shifts in place specific productivity that shifted the “optimal population” of a place. That is, if there are large, persistent, regional specific shocks to productivity (even after all accommodating policy and “institutional” responses) then if there is mobility of labor then people will move away. But if people are not mobile this will cause declining standards of living–even with a constant population–not because the population grew but because the “optimal population” fell. It is striking that the real wages for workers in Ireland never fell relative to the UK after the potato blight–but population fell to a third its previous level. In the discussion of regional “convergence” in the USA it is notable that Mississippi is a “low initial income, high growth in per capita income” state and California is a “high initial income, low growth in per capita income” state. The post-WWII development model created lots more countries in a global system that sharply limited population mobility across countries and hence turned country specific productivity shocks not into labor mobility but into a “population crisis” of sorts.
Demography and Savings: What is to be Done? This is a paper based on a speech in 1997 in which there was a group trying to promote the idea of a “demographic bonus” of the population transition through the mechanism that during the period of the population transition from high fertility to low fertility there would be more savings because of life-cycle effects (people dis-save and kids and dis-save as elders) so that the changing shape of the demographic pyramid would lead to higher savings and hence to higher economic growth. There is some small amount of truth to this, but, as the speech suggests, I thought this was mostly “demographic bogus” (a term I think I took from Angus Deaton who used it at this same conference as part of this own devastating critique of this argument).
How can many (or few) people support the earth? This speech was as a response to a 1995 book “How Many People Can the Earth Support?” by Joel Cohen, which was an excellent version of estimating the world’s “carrying capacity” for human beings. My response emphasized that part of the reason the Malthusian predictions have been wrong again and again and again for hundreds of years as they don’t take into account human responses to the natural environment. In particular, the social institutions for allocating entitlements to goods are endogenous to scarcity and one version of this is that when resources are abundant the costs of allocating “property” rights (including usufruct) are high relative to benefits but as they become scarce this (with responsive social institutions) this shifts and this shift creates incentives to economize, include ways to innovate to displace the need for the product. The counter-intuitive implication is that over-use is often a symptom of abundance, not scarcity, and the question is really about the speeds of adjustment to scarcity and the costs of resource replenishment (my HKS colleague Richard Zeckhauser has a good paper on this) and predictions about the “carrying capacity” of the Earth that do not endogenize human behavior, including social institutions for managing natural resources, are not very useful.
Environmental degradation and the demand for children: searching for the vicious circle in Pakistan (with Deon Filmer). Environment and Development Economics. Vol. 7, No. 1 (February 2002), pp. 123-146. This paper used time use data to explore a conjecture that there was a “vicious circle” between fertility and certain natural resources. The idea is that because children were used to collect goods like firewood and water and hence increased scarcity would increase the demand for children–but if everyone in an area had more children in response to scarcity, this would increase pressure on the resources and create more scarcity, leading to more demand for children, etc. until some collapse. It was interesting to explore this question using detailed household time use data from Pakistan as we found some parts of this narrative were true, others hard to document.
“Population Growth, Factor Accumulation, and Productivity.” World Bank Policy Research Working Paper, no. 1567, October 1995