A joint project of the UT-Austin Population Research Center and Economics Department.
The Population Wellbeing Initiative at UT-Austin is a network of researchers who conduct foundational research in economics, demography, and social welfare evaluation. We are a global priorities research center that specializes in quantitative social science research. Issue and project areas include: fertility, parenting, and the future of population and economic growth; infant and child welfare; animal welfare, and policy evaluation from a long-term perspective.
Core Research

Fertility, Parenting, and the Future of
Population Growth
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 matter just as much as the welfare of people alive today. 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?
People
Directors
Dean Spears – Director and Founder
Mark Budolfson – Coordinator for Philosophy
Diane Coffey – Coordinator for Demography
Mike Geruso – Coordinator for Economics
Researchers in Residence
Johan Gustafsson
Petra Kosonen
Kevin Kuruc
Narae Park
Christian Tarsney
Pre-doctoral Fellow
Selected Research
With a Whimper: Depopulation and Longtermism. Michael Geruso and Dean Spears. Forthcoming in Essays on Longtermism, Oxford University Press.
Abstract
“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.
Heritable Fertility is Not Sufficient for Long-Term Population Growth. 2021. Samuel Arenberg, Kevin Kuruc, Nathan Franz, Sangita Vyas, Nicholas Lawson, Melissa LoPalo, Mark Budolfson, Michael Geruso, and Dean Spears. Accepted at Demography.
Abstract
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.
Prudential Longtermism. Johan E. Gustafsson and Petra Kosonen.
Abstract
According to Longtermism, our acts’ expected influence on the value of the world is mainly determined by their effects in the far future. Given additive axiologies, such as total utilitarianism, there is a straightforward argument for Longtermism due to the enormous number of people that may exist in the future. This argument, however, does not work on person-affecting views. In this paper, we will argue that these views may, in fact, also lead to Longtermism. The reason they may do so is that Prudential Longtermism may be true. Prudential Longtermism holds for you if and only if our acts’ overall influence on your expected well-being is mainly determined by their effects in the far future. We argue that (due to a combination of anti-ageing, cryonics, uploading, and biological uploading) there could be an enormous amount of prudential value for you in the far future. This potential value may be so large that it dominates your overall expectation of lifetime well-being.
Foundations of Utilitarianism Under Risk and Variable Population. 2021. Dean Spears and Stéphane Zuber
Abstract
Utilitarianism is the most prominent family of social welfare functions. We present three new axiomatic characterizations of utilitarian (that is, additively separable) social welfare functions in a setting where there is risk over both population size and the welfares of individuals. First, we show that, given uncontroversial basic axioms, Blackorby et al.’s (1998) Expected Critical-Level Generalized Utilitarianism (ECLGU) is equivalent to a new axiom holding that it is better to allocate higher utility-conditional-on-existence to possible people who have a higher probability of existence. The other two novel characterizations extend classic axiomatizations of utilitarianism from settings with either social risk or variable-population, considered alone. By considering both social risk and variable population together, we clarify the fundamental normative considerations underlying utilitarian policy evaluation.
Temperature, Humidity, and Human Fertility: Evidence from 58 Developing Countries. 2021. Michael Geruso, Melissa LoPalo, and Dean Spears.
Abstract
A critical open question at the intersection of climate change and demography is the relationship between extreme climatic conditions and human fertility. In this paper, we study how temperature and humidity exposure affects human fertility in the developing world. We combine 142 rounds of Demographic and Health Survey datasets from low and middle income countries around the globe to create the most complete catalogue of fertility patterns linked to weather data to date. Importantly, our analysis separates the direct impacts of weather from other place-specific seasonal factors that may influence fertility. We find that exposure to extreme heat—relative to a village or urban area’s typical seasonal temperature profile—lowers birth rates nine months later. We find that the rebound in fertility in subsequent months is incomplete, suggesting the fertility declines due to extreme weather are not completely reversed with later additional childbearing. These results have significant implications for climate change, both in describing the potential fertility consequences of climate change and because optimal climate policy depends crucially on the expected size of future generations.
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.
Abstract
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.
Abstract
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.
Open Positions
We will be hiring for fall 2023, conditional on successful grant funding. We are recruiting researchers across disciplines with expertise in economics, demography, and social evaluation. We strive to recruit a diverse and inclusive team and offer competitive salaries and benefits to attract outstanding scholars.
Research Scientist
Research Scientists will collaborate actively with our team in the production of independent and coauthored research. Annually renewable while the research is successful and funded, potentially for years to come.
Self-directed Postdoctoral Researcher
Postdocs will conduct 100% self-directed research without teaching obligations, while also participating in program activities. Successful candidates will pair a 1-2 year postdoc with deferring the start of a new assistant professor position.
Predoctoral Fellow and Research Assistant
Predoctoral Fellows will support the research and activities of the program and participate in program activities, during a typically two-year period of preparation for a PhD.