Too Many Earthlings?

To the Editors:

I was surprised that Joel Cohen’s review [“The Case for More Babies,” NYR, April 24] didn’t take the opportunity to talk about the dangers posed by overpopulation. Is that because Cohen does not share my belief that overpopulation is the greatest danger confronting our species? It seems to me that all our efforts to curb the harm that we do to the planet are meaningless if we halve the consumption rate of individuals and have twice as many individuals. I agree with Jonathan Last in his book What To Expect When No One’s Expecting that the dangers he discusses are real, but I believe the dangers posed by his solutions are greater. I cannot understand the thinking of religious institutions that seem intent on maximizing the number of souls now rather than sustaining viable conditions in which those souls, for millennia to come, can die having lived lives worth having.

Dan Stroock
Professor of Mathematics Emeritus
Massachusetts Institute of Technology
Cambridge, Massachusetts

Joel E. Cohen replies:

For a successful airplane trip, six ingredients are necessary: thrust, lift, control of roll, control of pitch, control of yaw, and a place to land and take off. Lacking any one of these, the airplane will either never get off the ground or end in disaster.

So it is with the human populations of Earth. Human well-being depends on solving simultaneously the problems of population, economics, environment, and culture (including values, institutions, laws, languages, and religions). Solving demographic problems is a necessary, not a sufficient, condition for human well-being: see my “How Many People Can the Earth Support?,” NYR, October 8, 1998, and “Seven Billion,” The New York Times, October 23, 2011.

If I did not think that human population problems were important, I would not have spent much of my life studying them. What I have learned suggests that human population problems arise in a context of other equally significant problems that are also urgent on a wide variety of time scales. Dealing with the problems of human populations can make it easier to deal with the problems of economics, the environment, and culture; and, importantly, vice versa.

Focus on overpopulation narrows attention unproductively to a single number, the number of people. But human population problems are not adequately summarized by any single number. They include problems of spatial distribution, urbanization, age distribution, nutrition, health, and education. These problems vary widely in different regions of the world and, often, within a single country. Population problems wear many faces and require multifaceted responses.