Fertility, Parenting, and the Future of
In survey research, many women express a desire for two or more children, while citing economic and social constraints that lead them to expect to in fact have fewer. Does this gap represent an opportunity for innovations or policies to improve wellbeing by investing in children and parents and other caregivers? What will be the consequences for the economic and social welfare of future generations if low fertility becomes enduring negative population growth?
Quantitative Social Science of Open Ethical Questions
A range of ethical questions in the areas of environmental depletion, existential risk, global poverty, and depopulation require quantitative inputs for social evaluation. Because of disciplinary silos and historically weak communication between ethicists and social scientists, potentially answerable questions of fact that would serve as important inputs to ethical evaluations have remained unaddressed. Where can the technical toolsets of economists, demographers and other quantitative social scientists be best applied to fill these gaps in knowledge?
Social Welfare Functions and Population Ethics for Policy Evaluation
Important theoretical tools exist to evaluate social welfare in a way that aggregates the wellbeing of everyone equally. And compelling arguments in the social welfare and ethics literature establish that the wellbeing of animals and future generations matters. But public economics and social policy evaluation has not widely adopted these tools and insights. How can population social welfare functions that value the interests of everyone become more widely-used tools in policy evaluation?
New York Times piece (9/23) on the future of population published by Dean Spears.
New NIH grant awarded. 08/23 – 08/24. University of Texas-Austin Center on Aging and Population Sciences (P30AG066614, National Institute on Aging), “The Age Process of Fertility and Fecundity: New Facts and Implications for Population Dynamics.”
With a Whimper: Depopulation and Longtermism. Michael Geruso and Dean Spears. Forthcoming in Essays on Longtermism, Oxford University Press.
“Future people count. There could be a lot of them. We can make their lives go better.” This is Will MacAskill’s elegant and compelling introduction to longtermism for a popular audience in What We Owe the Future . It is the starting point of an argument for prioritizing the wellbeing of the near-endless stream of future people. Or, more specifically, people who may exist if humanity can evade the nearer term existential risks that threaten it. In this chapter, we consider an important other possibility: There might not be a lot of them, after all. The entire population science community predicts the global population to begin shrinking within the lives of children born today. Once this decline begins, it may happen fast. The goal of this chapter is to bring facts from population science and population economics into dialogue with the community of longtermists who are thinking about wellbeing into the far future. To eventually achieve a flourishing far future, it is valuable that over the coming few centuries a complex global economy endures and the number of people does not become small enough to be highly vulnerable to extinction from a threat that a larger population could sustain. We review population projections and other social scientific facts that show that fertility rates that are normal in much of the world today would cause population decline that is faster and to lower levels than is commonly understood, threatening the long term future.
Animal welfare: Methods to improve policy and practice. 2023. Mark Budolfson, Bob Fischer, Noah Scovronick. Published in Science.
There is growing international consensus that animal welfare is a crucial consideration in policy analysis, affecting domains ranging from food systems to biomedical research. Concern for animal welfare also features in many government regulations, certification programs, and institutional ethics codes across the globe and is central to many philanthropic and values-based investment decisions. However, although there are well-developed quantitative tools for incorporating human welfare into policy analysis, comparable tools for animal welfare are in their earliest stages. Without them, it is impossible to assess the net welfare impacts of a policy on humans and nonhumans alike on a common scale, which is crucial for making informed and transparent trade-offs (1). In practice, then, animal welfare is often ignored. Given that animal welfare matters in many cases, there is an urgent need for best-practice methods for integrating animal welfare into decision analyses.
Heritable Fertility is Not Sufficient for Long-Term Population Growth. 2022. Samuel Arenberg, Kevin Kuruc, Nathan Franz, Sangita Vyas, Nicholas Lawson, Melissa LoPalo, Mark Budolfson, Michael Geruso, and Dean Spears. Published in Demography.
All leading long-term global population projections agree on continuing fertility decline, resulting in a rate of population size growth that will continue to decline towards zero and would eventually turn negative. However, a literature inspired by mathematical biology has suggested that because fertility is heritable (i.e., higher-fertility parents tend to have higher-fertility children) and heterogeneous within a population, long-term population growth must eventually be positive. In this research note, we show that heritable fertility is not sufficient for positive long-term population growth, for empirical and theoretical reasons. First, empirically, even higher-fertility sub-populations show declining fertility rates which may eventually be below replacement (and in some populations already are). Second, in a simple Markov model, because heritability is imperfect, the combination of heritability and fertility rates may be quantitatively insufficient: it may be that higher-fertility parents nevertheless produce too few children who retain higher-fertility preferences. These results underscore the importance both of understanding the possible consequences of long-term fertility decline and depopulation and of the causal importance of culture and choice in human populations.
Utilitarian benchmarks for emissions and pledges promote equity, climate and development. 2021. Mark B. Budolfson, David Anthoff, Francis Dennig, Frank Errickson, Kevin Kuruc, Dean Spears, and Navroz K. Dubash. Published in Nature Climate Change.
Tools are needed to benchmark carbon emissions and pledges against criteria of equity and fairness. However, standard economic approaches, which use a transparent optimization framework, ignore equity. Models that do include equity benchmarks exist, but often use opaque methodologies. Here we propose a utilitarian benchmark computed in a transparent optimization framework, which, could usefully inform the equity benchmark debate. Implementing the utilitarian benchmark, which we see as ethically minimal and conceptually parsimonious, in two leading climate-economy models allows calculation of the optimal allocation of future emissions. We compare this optimum with historical emissions and initial Nationally Determined Contributions. Compared with cost-minimization, utilitarian optimization features better outcomes for human development, equity, and the climate. Peak temperature is lower under utilitarianism because it reduces the human development cost of global mitigation. Utilitarianism, therefore, is a promising inclusion to a set of benchmarks for future explorations of climate equity.
Population Ethics and the Prospects for Fertility Policy as Climate Mitigation Policy. 2021. Mark B. Budolfson and Dean Spears.
What are the prospects for using population policy as tool to reduce carbon emissions? In this paper, we review evidence from population science, in order to inform debates in population ethics that, so far, have largely taken place within the academic philosophy literature. In particular, we ask whether fertility policy is likely to have a large effect on carbon emissions, and therefore on temperature change. Our answer is no. Prospects for a policy of fertility-reduction-as-climatemitigation are limited by population momentum, a demographic factor that limits possible variation in the size of the population, even if fertility rates change very quickly. In particular, a hypothetical policy that instantaneously changed fertility and mortality rates to replacement levels would nevertheless result in a population of over 9 billion people in 2060. We use a leading climate-economy model to project the consequence of such a hypothetical policy for climate change. As a standalone mitigation policy, such a hypothetical change in the size of the future population – much too large to be implementable by any foreseeable government program – would reduce peak temperature change only to 6.4°C, relative to 7.1°C under the most likely population path. Therefore, fertility reduction is unlikely to be an adequate core approach to climate mitigation.
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