Concern about the ongoing decline in birth rates around the world has recently transformed from an arcane demographic preoccupation into a marquee political controversy. Many were indignant when it was revealed that the Trump administration was considering a variety of dubious measures to increase birth rates, from national medals for motherhood to barring Fulbright scholarships to the childless to small subsidies for new mothers (a “pro-family” “Trump accounts” scheme eventually made its way into the Big Beautiful Bill). Alongside the right-wing conferences convened to promote pronatalism, a flurry of articles and books have appeared debating the most efficacious way to reverse the downward trajectory of fertility rates, which are now at their lowest rate ever in the United States.
The latest entry in this genre, After the Spike: Population, Progress, and the Case for People by Dean Spears and Michael Geruso, significantly raises the stakes by insisting that falling fertility rates are a threat to the existence of human civilization itself. “Humanity is on a path to depopulation,” the opening line declares. In a matter of decades, homo sapiens will be on the back end of the “spike” in global human population that accompanied the Industrial Revolution, the authors predict, imperiling the fate of the species.
After the Spike is a provocative book with an epic sweep. Its authors present a plausible — but by no means certain — path for the trajectory of total human population over the course of the next several centuries. They are much less convincing when it comes to explaining why such a downward population trajectory would be disastrous.
Dean Spears and Michael Geruso are both economists affiliated with the Population Wellbeing Initiative (PWI) at the University of Texas at Austin. Geruso also served on the Biden administration’s Council of Economic Advisors. The ideas in the book were previewed in two New York Times op-eds, as well as a number of prior academic articles, one of which — “With a Whimper: Depopulation and Longtermism” — Spears has referred to as a “core PWI document.”
The “With a Whimper” paper is more candid about the authors’ intellectual background and motivations than the book itself. In it, Spears and Geruso state that their impulses for pondering these demographic questions are ultimately motivated by longtermist concerns. The word “longtermism” does not appear in After the Spike but refers to a view in moral philosophy that is intensely focused on the implications of present behavior for the potential long-term futures of humanity. Although this philosophy has many variations — some less objectionable than others — a crucial dilemma it examines is how to weigh the welfare of currently existing people against the welfare of potential future populations of people.
Most would not see anything objectionable in taking some account of the welfare of yet-unborn people — manifested in, for instance, a guideline to preserve the environment for the sake of future generations. More controversial are the extreme forms of longtermism that prioritize the welfare of future people in a manner oblivious to the concerns of, or even to the detriment of, existing people.
Some — including longtermism’s probably most notorious adherent, the cryptocurrency criminal Sam Bankman-Fried — have interpreted longtermism as entailing a mandate for self-enrichment, so that one might (in theory) use these funds for charitable giving in order to improve humanity’s lot. Yet others have viewed longtermism as a spur to avert potential existential risks to the human species. One more eschatological strain of longtermism in Silicon Valley has accelerated a frenzied development of artificial intelligence in order to avert the possibility of a rogue superintelligent computer that destroys humanity.
Spears and Geruso open “With a Whimper” by quoting the longtermist philosopher William MacAskill: “Future people count. There could be a lot of them. We can make their lives go better.” A precondition for making future lives “go better,” Spears and Geruso believe, is to mitigate the potential for human extinction in order to maximize the chance that these future people exist in the first place. The real concern for Spears and Geruso is not that population will fall to zero through fertility decline per se, but rather that population numbers will fall low enough such that the aggregate economic resources for averting some existential calamity would not exist. What catastrophe do they have in mind? An example, used both in the paper and the book, is an enormous asteroid hitting Earth. But they posit that their reasoning generalizes to other existential risks: pandemics, supervolcanos, climate change and rogue AI.
Another term that is not used in the book is “pronatalism.” Spears and Geruso’s argument is unquestionably a pronatalist one, as they are counseling a rise in global fertility rates.
The preoccupations of Spears and Geruso are shared by Elon Musk, the most prominent public figure with a noted concern about existential risk from population collapse. Musk gave a $10 million grant to PWI — clandestinely, until the source of the funding was exposed by a team of Bloomberg reporters. After the Spike might be viewed as elaborating a defense of Musk’s position on demography. (The Musk Foundation is thanked in the book’s acknowledgments.)
To their credit, Spears and Geruso keep their distance from many of the more unsavory trends within the pronatalist milieu. In the more recent New York Times op-ed, the authors dissociate themselves politically from the “right’s narrow pronatalist agenda, with its nostalgia for outdated gender roles and its blood-and-soil fixation on American birthrates.” Musk aside, the preoccupations of the motley crew of eugenics enthusiasts, white nationalists, and religious fundamentalists that often suffuse discussions of pronatalism find no place in the book. Rather than an argument about the composition of any population, present or future, Spears and Geruso keep the focus on the population’s overall numbers. In that sense, After the Spike represents a more respectable pronatalism than that often espoused by pronatalism’s usual politically conservative champions.
The main empirical claim of the book regards the trajectory that global population numbers are likely to take over the next several centuries. A familiar property of demographic history is the hockey-stick-shaped growth of global population over the past millennia: human population numbers were relatively modest until approximately the Industrial Revolution, when they exploded. Spears and Geruso’s conjecture that we are, give or take several decades, at the top of this global population “spike.” This apex will be followed, over the next several centuries, by a sharp fall in global population that is the mirror image of its rise in previous centuries. The United Nations predicts the peak of global population will occur in the 2080s, although some other estimates mark maximum global population as transpiring decades earlier.
The dynamic propelling this future population decline is falling fertility rates. Since just about every country in the world is already below replacement-level fertility, or seems to be headed in that direction, the unavoidable mathematical conclusion is that each generation after the spike will be smaller than the previous one. The logic of exponential decay will take over, rapidly (at least, relative to the time scale of human existence) pushing the global population down.
The prospects for a reversal of the downward trend of fertility rates would be unprecedented. Birth rates have been falling for centuries in developed countries, recently in low-income countries, and none of the twenty-six nations which has seen its fertility rate drop below 1.9 average births per woman has managed to push it above two, which the authors use as an approximation of replacement-rate fertility.
Demographers are often hesitant about projecting population too far into the future, but Spears and Geruso feel no restraint on this score. The UN projects population only until the year 2100, but Spears and Geruso blow by that milestone by centuries, even millennia. Depending on what level global fertility actually settles at, they observe, depopulation could come more or less quickly. However, regardless of how sub-replacement-level fertility trends, if one zooms out to the scale of centuries it will matter relatively little. Exponential decay will take over, and the global population will plummet.
The authors are well aware that demographic history over the next several centuries could take a different course from their vision. However, given the downward trend of fertility levels over the past centuries, and given that no country has managed to reverse sub-replacement fertility, Spears and Geruso’s scenario indeed seems like the most likely picture if we project current trends into the far future.
The first part of After the Spike lays out Spears and Geruso’s long-term projections of likely depopulation. The following sections contemplate the question “at the core of our book: Would depopulation be good or bad?” It will not surprise anyone who read their discussion of existential crisis in “With a Whimper” to know that Spears and Geruso think depopulation is bad, and they expand on that discussion in the book. But Spears and Geruso have additional reasons for being against population decline: an economic argument and an ethical one.
The economic argument has two components. The first is that idea generation will be greater with a larger population than a smaller one. “More of us generate more ideas,” Spears and Geruso write, “And that can mean better lives for each of us.” By “ideas” here, the authors seem to mean innovations contributing to productivity improvements that thereby increase aggregate economic output. Essentially, the argument is that everyone is potentially an idea generator, so a larger population will generate a greater number of ideas, thereby raising economic growth by virtue of technological innovation.
The second part of the economic argument centers on fixed costs. Certain economic activities require invariant expenditures, regardless of how many people supply or demand them. More people in the population means that these costs can be evenly spread among the population, lowering the per-capita cost for everyone. So if, say, preventing a civilization-ending asteroid from hitting Earth costs a certain number of dollars, paying that cost will be easier if spread among more contributors than fewer. Spears and Geruso argue that this fixed-costs argument generalizes to other civilization-protecting commodities such as vaccines: “In a world of 1 billion people, would we have been likely to get the mRNA technology we now have? We think the answer is far from a definite yes.”
Spears and Geruso’s ethical argument for larger populations derives from the niche field of population ethics. Although they have quite a bit to say about this aspect both in a chapter (“More good is better”) and an appendix, their argument is quite simple. In short: Human life is good. Therefore, more human life is better. Therefore, larger populations are preferable to smaller ones. Therefore, population stabilization (i.e., keeping the population at a constant level) is to be preferred to depopulation. This conclusion holds, they argue, even if additional lives will pull down the average well-being of the entire population.
Each of the arguments that Spears and Geruso make against global population decline has serious problems.
Spears and Geruso’s “more good is better” ethical argument is questionable on multiple fronts. For one thing, from the fact that human life is morally valuable in a familiar and intuitive sense — that it calls for certain kinds of protection and care — it does not obviously follow that we ought to prefer a greater number of human lives to a smaller one. The value of human life may not aggregate in this way, as non-consequentialist philosophers are keen to point out.
Maybe the bigger problem for Spears and Geruso, though, is that the “more good is better” argument doesn’t do the work they need it to do. It is really an argument not for mere stabilization but for unbounded population increase. They attempt to wiggle out of this implication in a number of ways, none of which is convincing.
In a couple places in the book, Spears and Geruso deny that their ethical principle is an argument for population growth, saying advocacy of such a trajectory would be “wildly irresponsible.” In another passage, the authors protest: “Of course it would be worse if everyone had twenty-five kids! . . . It’s a mistake to confuse ‘something would be good’ with ‘something would be the only good thing and should be our only goal to the exclusion of all other goals.’” But population growth only requires a birth rate above the replacement rate — approximately two children per woman — nowhere close to the absurd figure of twenty-five.
Furthermore, while it is almost certainly correct that we ought to have other goals besides that of promoting the existence of more human life, Spears and Geruso never say what these other goals are — nor do they explain why those goals only militate against population growth and not against their preferred population stabilization scenario. Whether one could mount an ethical case for population growth is an interesting question, but one that Spears and Geruso apparently have no inclination to defend. But their argument does lead to that conclusion.
Spears and Geruso’s desire to avoid advocacy of unbounded population growth is understandable, since doing so could leave them vulnerable to a recurrent worry in population ethics. That concern is that many philosophical views that aim at promoting human welfare imply that we ought morally to prefer a scenario where a very large population lives miserable lives to one where a smaller number of people live relatively happy lives — the so-called Repugnant Conclusion. The upshot for Spears and Geruso’s argument is that they have no grounds for objecting to a planet where billions of people newly brought into being will live lives that are nasty, brutish, and short.
Spears and Geruso are aware of this issue; in fact, they devote an appendix to the problem. There they argue that the Repugnant Conclusion cannot help us decide between two different ways of valuing different populations (total well-being vs. average well-being), since in certain conditions both views will imply the Repugnant Conclusion or something like it. Therefore, they say, the Repugnant Conclusion does not speak against their own view in population ethics. But this is a non sequitur: if their favored ethical principle has unacceptable implications, that undermines the principle whether or not it also counts against certain rival views. (Perhaps both sorts of views err in taking the value of human life to be aggregative, as mentioned above.)
Spears and Geruso’s economic arguments fare little better. With regard to the “ideas” component: it certainly is true that one of the wonderful qualities of human beings is that we are idea generators. However, it is quite a leap from that observation to concluding that every addition to a population will make an additional marginal contribution to productivity growth by virtue of their mental prowess. First, many ideas — even many very good ideas — have little to no economic value. Much of the output of the humanities never finds its way into the production process. Second, even for those ideas that do have some economic valence, the appropriate institutional enablements need to be in place for those ideas to eventually manifest themselves in the economic statistics.
This can be illustrated using Spears and Geruso’s chosen example of the development of COVID-19 mNRA vaccines. The vaccinations that people around the world received were the result of a decades-long effort of disconnected research and development efforts in academic and corporate labs. The select group of individuals that helped to advance the science behind the vaccines were highly educated academics and entrepreneurs with the appropriate institutional support and access to financing. A certain demographic reality was required for these scientists and inventors to exist in the first place — but they would not have been able to bring mRNA vaccines to fruition without a network of supportive institutions that no population bulge automatically brings into being. The relationship between population on the one hand and technological progress and living standards on the other falls short of “cause and effect.”
As for the argument about fixed costs, Spears and Geruso’s discussion of civilization-imperiling threats is too unmoored from any real scenario to have much weight. For the possibility of an asteroid hitting the earth, the authors give a figure of $10 trillion to avert this disaster. Where does this figure come from? Out of thin air.
To be persuasive, a discussion advocating a larger population to avert existential threats to humanity needs to be more specific. What existential threats are we as a species likely to face? What is a well-grounded estimate of the cost to avert them? How does the choice of which existential threat(s) to prioritize averting get made? And could a population stabilized at any level manage to pay the costs? It is one thing to observe that per-capita costs for any fixed amount reduce the more people are harnessed to the cause — assuming everyone successfully works together — and quite another to make an argument about these issues that isn’t wildly speculative.
But if we are to engage in ambitious speculation, it is worth acknowledging that existential threats to humanity might come from within the species rather than without (see the Vulnerable World Hypothesis). Spears and Geruso are aware of this issue — “The next child born might become the grand villain,” they write, and invent a “doomsday machine” — but quickly pass over it to focus exclusively on exogenous threats. But the potential of a civilization-ending threat coming from humanity’s own inventiveness belies the view advanced by the book that technological development and larger populations are unalloyed goods.
Just as with the ethical argument, Spears and Geruso’s economic arguments also seem to be arguments for population growth rather than just population stabilization. It is unclear why Spears and Geruso frame the book to rule out consideration of population growth. Perhaps the idea is that raising fertility rates to stabilization levels will be difficult enough, and the authors felt that it was better to focus on a more achievable goal. Or maybe it is a strategic move to reduce their vulnerability to critics who might be troubled by the Repugnant Conclusion; this way Spears and Geruso are less likely to be accused of wanting to introduce billions of (potentially miserable) people into the population. Or perhaps it is even an implicit concession to their environmentalist interlocutors — Paul Ehrlich and Bill McKibben are both mentioned in the book — who associate population growth with planetary despoliation.
Even within their stated goal of population stabilization, Spears and Geruso refuse to indicate what level of population they believe would be best. “This book makes the case to stabilize somewhere,” they say. “Exactly where will have to be a question for public and scientific debate.” Given the arguments in the rest of the book, it would seem they think that stabilization at a higher level is preferable.
After the Spike is relentlessly optimistic in tone: the past is a history of continuous progress, and the future is a horizon of — Spears and Geruso often invoke the au courant term — abundance. So it might come as a jolt to some readers when Spears and Geruso concede at the end of the book that they have no theory explaining why fertility rates continue to decline and no plan to avert this possibility. Instead, they implore the reader to “join the conversation” about how humanity can raise its birth rates.
In fairness to Spears and Geruso, no one has yet articulated a convincing explanation of the contemporary continual plunge of fertility rates worldwide. The authors entertain the idea that the root cause might be due to the rising opportunity costs of raising children — that is, the increasing attractiveness of alternatives to raising children like career, leisure, education, and entertainment — before ultimately rejecting this hypothesis. Regardless of the causes, Spears and Geruso observe that coercive government interventions (which, to their credit, they oppose) have proven unable to change their populations’ long-term fertility outcomes.
Spears and Geruso insist that they are “not declaring a crisis,” at least not yet. But if their predictions come to pass, and humanity finds itself on the back end of the population spike, it will be the first time in the history of humanity when the species has found itself experiencing rapid and prolonged population decline. We would be entering a truly unique demographic epoch, with few certainties about what such population changes might bring.
After the Spike’s contribution, despite its shortcomings, is to challenge its readers to ponder the possibility and implications of this unexampled potential demographic future. Insofar as declining birth rates are due to people being unable to have as many children as they would like, that is a problem for which the Left should have a serious response. And if fertility decline does end up reducing economic growth, that will mean a sharpening of conflicts over the distribution of society’s wealth. But insofar as these and other considerations give us well-founded reasons to worry about birth rates, Spears and Geruso’s focus is strangely elsewhere.
Great Job Daniel Colligan & the Team @ Jacobin Source link for sharing this story.