Optimal population and exhaustible resource constraints
A large literature considers the optimal size and growth rate of the human population, trading off the utility value of additional people with the costs of a larger population. In this literature, an important parameter is the social weight placed on population size; a standard result is that a planner with a larger weight on population chooses larger population levels and growth rates. We demonstrate that this result is conditionally overturned when an exhaustible resource constraint is introduced: if the discount rate is small enough, the optimal population today decreases with the welfare weight on population size. That is, a more total-utilitarian social planner could prefer a smaller population today than a more average-utilitarian social planner. We also present a numerical illustration applied to the case of climate change, where we show that under plausible real-world parameter values, our result matters for the direction and magnitude of optimal population policy.
KeywordsOptimal population Climate change Social choice and welfare Exhaustible resources Population ethics and policy Utilitarianism
JEL ClassificationJ10 J19 I31
We would like to thank Raouf Boucekkine, David de la Croix, Giorgio Fabbri, Marc Fleurbaey, and seminar participants at the University of Copenhagen and the Indian Statistical Institute—Delhi for their comments. We are especially grateful for the help and guidance provided by two anonymous referees of this journal and by the editor. Any errors or omissions are the responsibility of the authors.
Compliance with ethical standards
This project received no funding. The authors declare that they have no conflict of interest. Although unrelated to this project, Dean Spears, in his capacity of Executive Director of r.i.c.e. (a 501(c)3 public charity), has received grants from the Bill and Melinda Gates Foundation, the NIH, USAID, and the IGC, and has been a paid consultant for the World Bank.
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