Dasgupta, A., and P. Dasgupta. (2021) “Population Overshoot“, in K. Bykvist and T. Campbell, eds., Oxford Handbook of Population Ethics, Oxford: Oxford University Press, forthcoming.

Externalities are the unaccounted for consequences for others of actions taken by
one or more persons. They are symptoms of institutional failure, which is why they
cannot be eliminated without collective action. When externalities are adverse, the moral
directives flowing from them can clash with the exercise of personal rights. In this paper
we identify a class of environmental externalities in the contemporary world that
accompany procreation. We also identify externalities that are allied to socially embedded
preferences for family size. Those preferences can give rise to a heightened demand for
children, which exacerbates the adverse environmental externalities present people
impose on future generations. Crude but suggestive estimates of the demand humanity
currently makes on the biosphere are used to show that adverse environmental
externalities accompanying new births are significant. We use data on global economic
demography to provide rough estimates of the size of the human population the Earth
system can support at an acceptable standard of living. Our analysis, which is designed
only to raise questions that have been much neglected in economic demography, allows
us to study the sensitivity of sustainable global population to the standard of living.