A RESEARCH STATEMENT is available at the bottom of this page
WORKING PAPERS
‣ Doing the right thing (or not) in a lemons-like situation: on the role of social preferences and Kantian moral concerns With José Ignacio Rivero-Wildemauwe.
Non-technical abstract: Experimental evidence from the past decades shows that a sizeable share of participants in laboratory experiments are not always willing to inflict a reduction in others' material payoffs in order to obtain a larger payoff. In this paper we conduct an experiment in which the instructions to participants describe the task as the sale of a "lemon" to a willing buyer: the "seller" gains from selling, while the buyer's payoff is reduced (this is reminiscent of a situation where the good has a defect, which the buyer is unaware of); a decision to "not sell" neither increases nor decreases the payoffs of the "seller" and the "buyer". We compare the participants' decisions in this setting with decisions taken in payoff-equivalent decisions, but described in neutral terms (the decisions are called X and Y). We find that participants are more likely to select the selfish action under the market framing. Furthermore, we seek to disentangle two distinct reasons for why participants would refrain from the selfish action: a pro-social concern, (whereby the individual cares about the other's payoff) and a Kantian moral concern (whereby an individual evaluates each action in light of what their own material payoff would be if, hypothetically, the roles were reversed and the other were to select the same action). By varying the salience of the arbitrariness of the role distribution, we arguably vary the extent to which participants' Kantian moral concerns are triggered. In accordance with this hypothesis, we find that increased salience make the participants less likely to select the selfish action.
‣ Does universalization ethics justify participation in large elections? With Konrad Dierks and Jean-François Laslier.
Non-technical abstract: Why do voters incur costs to participate in large elections? This paper proposes an exploratory analysis of the implications of evolutionary Kantian morality for this classical problem in the economic theory of voting: the costly participation problem.
PUBLISHED AND FORTHCOMING
‣ Estimating social preferences and Kantian morality in strategic interactions. With Boris van Leeuwen. Forthcoming Journal of Political Economy Microeconomics.
Non-technical abstract: Recent theoretical work suggests that a form of Kantian morality has evolutionary foundations. To investigate the relative importance of Kantian morality and social preferences, we run laboratory experiments on strategic interaction in social dilemmas. Using a structural model, we estimate social preferences and morality concerns both at the individual level and the aggregate level. We observe considerable heterogeneity in social preferences and Kantian morality. A finite mixture analysis shows that the subject pool is well described as consisting of two types. One exhibits a combination of inequity aversion and Kantian morality, while the other combines spite and Kantian morality. The value of adding Kantian morality to well-established preference classes is also evaluated.
‣ Evolution of semi-Kantian preferences in two-player assortative interactions with complete and incomplete information and plasticity With Laurent Lehmann. Dynamic Games and Applications, Vol. 13, 2023, 1288-1319.
Non-technical abstract: Previous work (Alger and Weibull, 2013, 2016) shows that Homo moralis preferences with a certain degree of morality are evolutionarily stable, in the sense that once a population consists almost entirely of individuals with such preferences, no other preferences (from with the set of all continuous utility functions) can displace them. This previous work considered populations in which individuals interact without being able to observe each other's preferences (i.e., under incomplete information). Here, we focus on the class of Homo moralis preferences (referred to as semi-Kantian) and examine two notions of evolutionary viability of the value of the degree of morality: evolutionary stability, and convergence stability, where the latter means that a population that has reached a state in which all individuals have a degree of morality close to the evolutionarily stable one, selection pressure will eventually lead to the evolutionarily stable one. We do this in three distinct scenarios: (a) incomplete information; (b) complete information and incomplete plasticity (interacting individuals can observe each other's preferences, but an individual's preferences cannot be conditioned on the other's preferences); and (c) complete information and complete plasticity (interacting individuals can observe each other's preferences, and an individual's preferences may depend on the other's preferences).
‣ The evolution of early hominin food production and sharing With Slimane Dridi, Jonathan Stieglitz, and Michael Wilson. Proceedings of the National Academy of Sciences, Vol. 120 (25), 2023, e2218096120.
Non-technical abstract: Human foragers share plant and animal foods extensively. Influential scenarios for the evolution of hominin food sharing focus on either scavenging, hunting, or cooking. However, evidence of extractive foraging for nutrient-dense plant foods millions of years before the emergence of these activities suggests food sharing potentially emerged earlier. We present a novel conceptual and mathematical model of the evolution of food production and sharing in early hominins across diverse mating systems. Male mate guarding protects females from food theft, permitting females to increase extractive foraging time and efficiency. Increased efficiency motivates females to share food with males when pair bonds exist. Female provisioning of males may have catalyzed the evolution of uniquely hominin traits prior to dietary reliance on meat.
‣ Evolution and Kantian morality: a correction and addendum. With Jörgen W. Weibull. Games and Economic Behavior, Vol. 140, 2023, 585-587.
Non-technical abstract: In this note we correct a mistake found in our earlier paper Alger and Weibull (Games and Economic Behavior, 2016) (the mistake consisted in using a definition that assumed equilibrium existence, while not guaranteeing such existence). As a by-product, we also obtain an extension of a result found in Alger and Weibull (Econometrica, 2013).
‣ Evolutionarily stable preferences Philosophical Transactions of the Royal Society B, Vol. 378, 2023, 20210505.
Non-technical abstract: The 50-year old definition of an evolutionarily stable strategy (ESS) provided a key tool for theorists to model ultimate drivers of behavior in social interactions. For decades economists ignored ultimate drivers and used models in which individuals choose strategies based on their preferences—a proximate mechanism for behavior, taken to be fixed and given. This article summarizes some key findings in the literature on evolutionarily stable preferences, which in the past three decades has proposed models that combine the two approaches: individuals inherit their preferences, the preferences determine their strategy choices, which in turn determines evolutionary success. One objective is to highlight complementarities and potential avenues for future collaboration between biologists and economists.
‣ Do women contribute more than men to a real public good? With Laura Juarez, Miriam Juarez-Torres, and Josepa Miquel-Florensa. World Bank Economic Review, Vol. 37, 2023, 205-220.
Non-technical abstract: We present evidence from a lab-in-the-field experiment, conducted in eight small, rural villages in Mexico, in which subjects choose to exert real effort to fund real health centers in their own and other localities. We find that women are more willing than men to exert effort to fund the health center in another locality, relative to the one in their locality. This gender gap is mostly due to women who have some trust in the way the government spends taxes, and to women who benefit from a government program that targets women and fosters health care use. Our results also suggest that women might be aware of their higher willingness to exert effort for a public good that does not benefit them directly, compared to men, because they seem to reduce their individual effort the more female their environment is.
‣ Homo moralis goes to the voting booth: coordination and information aggregation. With Jean-François Laslier. Journal of Theoretical Politics Vol. 34, 2022, 280-312.
Non-technical abstract: This paper revisits two classical problems in the theory of voting-viz. the divided majority problem and the strategic revelation of information by majority vote-in the light of evolutionarily founded partial Kantian morality. It is shown that, compared to electorates consisting of purely self-interested voters, such Kantian morality helps voters solve coordination problems and improves the information aggregation properties of equilibria, even for modest levels of morality.
‣ On the evolution of male competitiveness. Journal of Economic Behavior and Organization Vol. 190, 2021, 228-254.
Non-technical abstract: Since a man’s reproductive success depends on his ability to outcompete other men, male com- petitiveness may be expected to have been exposed to strong selective pressure throughout hu- man history. Accordingly, the relatively low level of physical violence observed between men has been viewed as a puzzle. What could have limited the eagerness of men to out-compete each other? I study the evolution of male competitiveness in a model where men compete for both reproductive and productive resources. I show that high levels of male competitiveness are then consistent with evolution by natural selection if (a) the ecology is generous enough for men to supply little or no food to their children, (b) competing is not too costly in terms of productive resources, and (c) relatedness among males is low enough.
‣ Paternal provisioning results from ecological change. Proceedings of the National Academy of Sciences Vol.117, 2020, 10746-10754. With Donald Cox, Paul Hooper, Hillard Kaplan, and Jonathan Stieglitz.
Non-technical abstract: Paternal provisioning is ubiquitous in human subsistence societies and unique among apes. How could paternal provisioning have emerged from promiscuous or polygynous mating systems that characterize other apes? An anomalous provisioning male would encounter a social dilemma: Since this investment in prospective offspring can be expropriated by other males, this investment is unlikely to increase the provisioner’s fitness. We present an ecological theory of the evolution of human paternal investment. Ecological change favoring reliance on energetically rich, difficult-to-acquire resources increases payoffs to paternal provisioning due to female–male and/or male–male complementarities. Paternal provisioning becomes a viable reproductive strategy when complementarities are strong, even under high paternity uncertainty. This model illuminates additional paths for understanding the evolution of fatherhood.
‣ Does informal risk sharing induce lower efforts? Evidence from lab-in-the-field experiments in rural Mexico. Economic Development and Cultural Change Vol. 69, 2020, 107-171. With Laura Juarez, Miriam Juarez-Torres, and Josepa Miquel-Florensa.
Non-technical abstract: There is evidence that informal transfers in developing countries have a negative impact on investment and productive efforts. This article reports results based on experimental data collected in villages of self-subsisting farmers in Mexico. The data allowed us to analyze how the anticipation of giving or receiving transfers affect real effort choices. We find that on average, subjects either make the same or a slightly higher productive effort when they face potential transfers than when no transfers are involved (and the effort thus has an effect only on the subject him- or herself). The study uses a novel experimental design, which presents the advantage of involving no income effects and of enabling study of real effort choices in payoff-equivalent tasks which differ only in whether transfers occur or not.
‣ Evolution of preferences in group-structured populations: genes, guns, and culture. Journal of Economic Theory Vol.185, 2020, 104951. With Jörgen W. Weibull and Laurent Lehmann.
Non-technical abstract: Although moral values have been part of human thinking for thousands of years, economists have tended to disregard this. Our model examines the evolutionary foundations of moral values. It leads to two main results. First, when individuals reflect on the consequences of their actions on fitnesses, a combination of self-interest and a particular kind of Kantian moral (non-consequentialistic) concern is shown to be compatible with natural selection. Second, when individuals reflect on the consequences of their actions on material payoffs, a combination of self-interest, a (non-consequentialistic) Kantian moral concern, and a (consequentialistic) concern about the others' material payoffs is shown to be compatible with natural selection. The (consequentialistic) concern may be either pro-social (altruism) or anti-social (spite). The article builds on our earlier work (see the article published in Evolution in 2015). It combines the “island model”, a classic model used by evolutionary biologists to study the effects of population structure, with game theory and classic models of preference evolution in economics, to examine which preferences cannot be displaced by other strategies once they have become prevalent in a population.
‣ Morality: evolutionary foundations and economic implications. in Basu, K., D. Rosenblatt, and C. Sepulveda, eds., 2020, The State of Economics, the State of the World, Cambridge: MIT Press. With Jörgen W. Weibull.
Non-technical abstract: This book chapter was written for the conference on “The State of Economics, the State of the World,” organized in June 2016 by Kaushik Basu (Chief Economist of the World Bank), to which Jörgen had been invited together with Philippe Aghion, Kenneth Arrow, Guillermo Calvo, Esther Duflo, Amartya Sen, Hyun Song Shin, Nicholas Stern, Joseph Stiglitz, and Cass Sunstein. The chapter summarizes our research on the evolutionary foundations of homo moralis preferences, and discusses some implications of such moral preferences for economic policy.
‣ Evolution of the family: theory and implications for economics. In Oxford Research Encyclopedia of Economics and Finance, November 2019. Oxford University Press. With Donald Cox.
Non-technical abstract: Which parent can be expected to be more altruistic toward their child, the mother or father? All else equal, can we expect older generation members to be more solicitous of younger family members or vice versa? Policy interventions often target recipients by demographic status: more money being put in the hands of mothers, say, or transfers of income from young to old via public pensions. Economics makes predictions about pecuniary incentives and behavior but tends to be agnostic about how, say, a mother might behave, just because she is a mother. Evolutionary theory fills this gap by analyzing how preferences of family members emerge from the Darwinian exigencies of “survive and reproduce.” The article discusses several implications for economics. Moroever, an original case study is provided, which explains the puzzle of diverging marriage rates by education in terms of heterogeneity in preferences for commitment.
‣ Evolutionary models of preference formation. Annual Review of Economics Vol.11, 2019, 329-354. With Jörgen W. Weibull.
Non-technical abstract: This article reviews the theoretical literature on the evolution of preferences that guide behavior in strategic interactions.
‣ Strategic behavior of moralists and altruists. Games Vol. 8(3), 38, 2017. With Jörgen W. Weibull.
Non-technical abstract: In our Econometrica (2013) article (see also the article in Games and Economic Behavior, 2016), we proposed a model of preference evolution in strategic interactions in which the mathematics led to a certain utility function that has hitherto not been studied in economics. Our analysis showed that this utility function is the only one which is evolutionarily stable for the entire set of strategic interactions that we consider. In this article, we study the behavior of such homo moralis preferences in a variety of interactions, such as the one-shot prisoners’ dilemma, a two-player infinitely repeated investment game, and n-player coordination games. We compare behavior of homo moralis to that of individuals equipped with altruistic preferences.
‣ Evolution and Kantian morality. Games and Economic Behavior Vol. 98, 2016, 56-67. With Jörgen W. Weibull.
Non-technical abstract: This article examines extends the analysis of the Econometrica (2013) article (see below) to the case of n-player interactions.
‣ Does evolution lead to maximizing behavior? Evolution Vol. 69, 2015, 1858-1873. With Laurent Lehmann and Jörgen W. Weibull.
Non-technical abstract: This article combines the “island model”, a classic model used by evolutionary biologists to study the effects of population structure, with game theory to examine whether strategies that cannot be displaced by other strategies once they have become prevalent in a population, can be viewed as emanating from individual utility-maximizing behavior.
‣ Homo moralis — preference evolution under incomplete information and assortative matching. Econometrica Vol. 81, 2013, 2269-2302. [Extensive Working Paper version] With Jörgen W. Weibull.
Non-technical abstract: This article examines the evolutionary viability of preferences that guide behavior in strategic interactions involving two individuals (such as public goods games, prisoner’s dilemmas, coordination games, common pool resource games, etc). The mathematical analysis leads to a class of preferences that has not been studied before in economics. We call these preferences homo moralis, since one possible interpretation of this class of preferences is that it induces its carrier to evaluate each strategy not only in light of the material payoff (s)he would obtain from using this strategy, but also in light of the material payoff (s)he would obtain if, hypothetically, the other player were to use this strategy. This Kantian-flavored motive receives a weight that reflects the probability with which rare mutants would get to interact. The intuition is that such preferences induce their carriers to play a strategy that would maximize the fitness of rare mutants; in other words, when most people in a population have homo moralis preferences, equilibrium play preempts entry by other preferences.
‣ The evolution of altruistic preferences: mothers versus fathers. Review of Economics of the Household Vol. 11, 2013, 421-446. With Donald Cox.
Non-technical abstract: This article reviews the theoretical literature on the evolutionary roots of preferences driving parental care, with a focus on factors that may have led these preferences to differ between mothers and fathers.
‣ Experience benefits and firm organization. B.E. Journal of Economic Analysis & Policy Vol. 12: Issue 1 (Contributions), Article 39, 2012. With Ching-to Albert Ma and Régis Renault.
Non-technical abstract: This article examines the trade-offs that a firm faces when it chooses between hiring employees and outsourcing work to independent entrepreneurs. On the one hand, the firm faces less severe information problems with in-house production than with outsourcing, but on the other hand it can extract more of the rent associated with on-the-job experience from under outsourcing than under in-house production.
‣ A generalization of Hamilton's rule — Love others how much? Journal of Theoretical Biology Vol. 299, 2012, 42-54. [Click here for illustrating plots (due to Kristaps Dzonsons)] With Jörgen W. Weibull.
Non-technical abstract: Suppose that the extent to which individuals care for other’s material well-being (as captured by their “degree of altruism”) is a preference trait that is transmitted from parents to children. The article shows that evolution by natural selection may then have led the degree of altruism to depend on the specifics of the interaction. In particular, if the interaction involves strategic complementarities, an evolutionarily stable degree of altruism is higher than if it involves strategic substitutabilities.
‣ Public goods games, altruism, and evolution. Journal of Public Economic Theory Vol. 12, 2010, 789-813.
Non-technical abstract: Suppose that the extent to which individuals care for other’s material well-being (as captured by their “degree of altruism”) is a preference trait that is transmitted from parents to children. The article shows that evolution by natural selection may then have led the degree of altruism to depend on the specifics of the interaction. The model focuses on interactions with strategic substitutabilities between the individuals’ strategies.
‣ Kinship, incentives and evolution. American Economic Review Vol. 100, 2010, 1725-1758. With Jörgen W. Weibull.
Non-technical abstract: Suppose that the strength of family ties (as captured by intra-family altruism and the associated amount of helping behaviors within families) is transmitted from parents to children. The article shows that evolution by natural selection may then have led the strength of family ties to differ across different parts of the world in in pre-industrial agricultural societies. In particular, the model predicts that weaker family ties are to be expected in harsher environments.
‣ Family ties, incentives and development: a model of coerced altruism. in Basu, K., and R. Kanbur, eds., 2008, Arguments for a Better World: Essays in Honor of Amartya Sen, Volume II: Society, Institutions and Development, Oxford: Oxford University Press. With Jörgen W. Weibull.
Non-technical abstract: In many countries a social norm requires a relatively wealthy individual to help his/her poorer relatives. The book chapter shows that such “kin taxes” either weaken or strengthen an individual’s incentive to provide productive efforts, depending on whether the norm is in line with the individual’s intrinsic preferences.
‣ Screening ethics when honest agents keep their word. Economic Theory Vol. 30, 2007, 291-311. With Régis Renault.
Non-technical abstract: Some individuals are unwilling to misrepresent their private information. The article formalizes a kind of “honesty” in an otherwise standard principal-agent model, and shows that it provides a rationale for contracts that request the agent to report non-verifiable information.
‣ A theory of fraud and over-consumption in experts markets. Journal of Economics, Management & Strategy Vol. 15, 2006, 853-881. With François Salanié.
Non-technical abstract: Experts (such as mechanics, dentists, physicians, and lawyers) may be tempted to over-treat their customers if the prices they charge give them an incentive to do so; by characterizing equilibrium prices in a competitive experts market, the article identifies conditions that lead to equilibrium over-treatment.
‣ Screening ethics when honest agents care about fairness. International Economic Review Vol. 47, 2006, 59-85. With Régis Renault.
Non-technical abstract: Some individuals are unwilling to misrepresent their private information. The article formalizes several forms of “honesty” in an otherwise standard principal-agent model, and shows that some forms of honesty are more exploitable than others.
‣ Moral hazard, insurance, and some collusion. Journal of Economic Behavior and Organization Vol. 50, 2003, 225-247. With Ching-to Albert Ma.
Non-technical abstract: Fraudulent insurance claims can be deterred with adequate contract design; the article investigates contract design when only some customers would consider defrauding the insurer.
‣ Consumer strategies limiting the monopolist's power: multiple and joint purchases. RAND Journal of Economics Vol. 30, 1999, 736-757.
Non-technical abstract: The classic models of second-degree price discrimination (Maskin and Riley, 1984, Mussa and Rosen, 1978) rely on the assumption that consumers cannot purchase multiple "bundles" or make joint purchases of bundles. This article lifts this assumption. This leads to an original and intuitive rationale for quantity discounts.
DORMANT PAPERS
‣ Liquid assets in banks: theory and practice (with Guillermo Alger) [WP Boston College 446]
‣ Optimal debt contracts when credit managers are (perhaps) corruptible [WP Boston College 648]
WORKING PAPERS
‣ Doing the right thing (or not) in a lemons-like situation: on the role of social preferences and Kantian moral concerns With José Ignacio Rivero-Wildemauwe.
Non-technical abstract: Experimental evidence from the past decades shows that a sizeable share of participants in laboratory experiments are not always willing to inflict a reduction in others' material payoffs in order to obtain a larger payoff. In this paper we conduct an experiment in which the instructions to participants describe the task as the sale of a "lemon" to a willing buyer: the "seller" gains from selling, while the buyer's payoff is reduced (this is reminiscent of a situation where the good has a defect, which the buyer is unaware of); a decision to "not sell" neither increases nor decreases the payoffs of the "seller" and the "buyer". We compare the participants' decisions in this setting with decisions taken in payoff-equivalent decisions, but described in neutral terms (the decisions are called X and Y). We find that participants are more likely to select the selfish action under the market framing. Furthermore, we seek to disentangle two distinct reasons for why participants would refrain from the selfish action: a pro-social concern, (whereby the individual cares about the other's payoff) and a Kantian moral concern (whereby an individual evaluates each action in light of what their own material payoff would be if, hypothetically, the roles were reversed and the other were to select the same action). By varying the salience of the arbitrariness of the role distribution, we arguably vary the extent to which participants' Kantian moral concerns are triggered. In accordance with this hypothesis, we find that increased salience make the participants less likely to select the selfish action.
‣ Does universalization ethics justify participation in large elections? With Konrad Dierks and Jean-François Laslier.
Non-technical abstract: Why do voters incur costs to participate in large elections? This paper proposes an exploratory analysis of the implications of evolutionary Kantian morality for this classical problem in the economic theory of voting: the costly participation problem.
PUBLISHED AND FORTHCOMING
‣ Estimating social preferences and Kantian morality in strategic interactions. With Boris van Leeuwen. Forthcoming Journal of Political Economy Microeconomics.
Non-technical abstract: Recent theoretical work suggests that a form of Kantian morality has evolutionary foundations. To investigate the relative importance of Kantian morality and social preferences, we run laboratory experiments on strategic interaction in social dilemmas. Using a structural model, we estimate social preferences and morality concerns both at the individual level and the aggregate level. We observe considerable heterogeneity in social preferences and Kantian morality. A finite mixture analysis shows that the subject pool is well described as consisting of two types. One exhibits a combination of inequity aversion and Kantian morality, while the other combines spite and Kantian morality. The value of adding Kantian morality to well-established preference classes is also evaluated.
‣ Evolution of semi-Kantian preferences in two-player assortative interactions with complete and incomplete information and plasticity With Laurent Lehmann. Dynamic Games and Applications, Vol. 13, 2023, 1288-1319.
Non-technical abstract: Previous work (Alger and Weibull, 2013, 2016) shows that Homo moralis preferences with a certain degree of morality are evolutionarily stable, in the sense that once a population consists almost entirely of individuals with such preferences, no other preferences (from with the set of all continuous utility functions) can displace them. This previous work considered populations in which individuals interact without being able to observe each other's preferences (i.e., under incomplete information). Here, we focus on the class of Homo moralis preferences (referred to as semi-Kantian) and examine two notions of evolutionary viability of the value of the degree of morality: evolutionary stability, and convergence stability, where the latter means that a population that has reached a state in which all individuals have a degree of morality close to the evolutionarily stable one, selection pressure will eventually lead to the evolutionarily stable one. We do this in three distinct scenarios: (a) incomplete information; (b) complete information and incomplete plasticity (interacting individuals can observe each other's preferences, but an individual's preferences cannot be conditioned on the other's preferences); and (c) complete information and complete plasticity (interacting individuals can observe each other's preferences, and an individual's preferences may depend on the other's preferences).
‣ The evolution of early hominin food production and sharing With Slimane Dridi, Jonathan Stieglitz, and Michael Wilson. Proceedings of the National Academy of Sciences, Vol. 120 (25), 2023, e2218096120.
Non-technical abstract: Human foragers share plant and animal foods extensively. Influential scenarios for the evolution of hominin food sharing focus on either scavenging, hunting, or cooking. However, evidence of extractive foraging for nutrient-dense plant foods millions of years before the emergence of these activities suggests food sharing potentially emerged earlier. We present a novel conceptual and mathematical model of the evolution of food production and sharing in early hominins across diverse mating systems. Male mate guarding protects females from food theft, permitting females to increase extractive foraging time and efficiency. Increased efficiency motivates females to share food with males when pair bonds exist. Female provisioning of males may have catalyzed the evolution of uniquely hominin traits prior to dietary reliance on meat.
‣ Evolution and Kantian morality: a correction and addendum. With Jörgen W. Weibull. Games and Economic Behavior, Vol. 140, 2023, 585-587.
Non-technical abstract: In this note we correct a mistake found in our earlier paper Alger and Weibull (Games and Economic Behavior, 2016) (the mistake consisted in using a definition that assumed equilibrium existence, while not guaranteeing such existence). As a by-product, we also obtain an extension of a result found in Alger and Weibull (Econometrica, 2013).
‣ Evolutionarily stable preferences Philosophical Transactions of the Royal Society B, Vol. 378, 2023, 20210505.
Non-technical abstract: The 50-year old definition of an evolutionarily stable strategy (ESS) provided a key tool for theorists to model ultimate drivers of behavior in social interactions. For decades economists ignored ultimate drivers and used models in which individuals choose strategies based on their preferences—a proximate mechanism for behavior, taken to be fixed and given. This article summarizes some key findings in the literature on evolutionarily stable preferences, which in the past three decades has proposed models that combine the two approaches: individuals inherit their preferences, the preferences determine their strategy choices, which in turn determines evolutionary success. One objective is to highlight complementarities and potential avenues for future collaboration between biologists and economists.
‣ Do women contribute more than men to a real public good? With Laura Juarez, Miriam Juarez-Torres, and Josepa Miquel-Florensa. World Bank Economic Review, Vol. 37, 2023, 205-220.
Non-technical abstract: We present evidence from a lab-in-the-field experiment, conducted in eight small, rural villages in Mexico, in which subjects choose to exert real effort to fund real health centers in their own and other localities. We find that women are more willing than men to exert effort to fund the health center in another locality, relative to the one in their locality. This gender gap is mostly due to women who have some trust in the way the government spends taxes, and to women who benefit from a government program that targets women and fosters health care use. Our results also suggest that women might be aware of their higher willingness to exert effort for a public good that does not benefit them directly, compared to men, because they seem to reduce their individual effort the more female their environment is.
‣ Homo moralis goes to the voting booth: coordination and information aggregation. With Jean-François Laslier. Journal of Theoretical Politics Vol. 34, 2022, 280-312.
Non-technical abstract: This paper revisits two classical problems in the theory of voting-viz. the divided majority problem and the strategic revelation of information by majority vote-in the light of evolutionarily founded partial Kantian morality. It is shown that, compared to electorates consisting of purely self-interested voters, such Kantian morality helps voters solve coordination problems and improves the information aggregation properties of equilibria, even for modest levels of morality.
‣ On the evolution of male competitiveness. Journal of Economic Behavior and Organization Vol. 190, 2021, 228-254.
Non-technical abstract: Since a man’s reproductive success depends on his ability to outcompete other men, male com- petitiveness may be expected to have been exposed to strong selective pressure throughout hu- man history. Accordingly, the relatively low level of physical violence observed between men has been viewed as a puzzle. What could have limited the eagerness of men to out-compete each other? I study the evolution of male competitiveness in a model where men compete for both reproductive and productive resources. I show that high levels of male competitiveness are then consistent with evolution by natural selection if (a) the ecology is generous enough for men to supply little or no food to their children, (b) competing is not too costly in terms of productive resources, and (c) relatedness among males is low enough.
‣ Paternal provisioning results from ecological change. Proceedings of the National Academy of Sciences Vol.117, 2020, 10746-10754. With Donald Cox, Paul Hooper, Hillard Kaplan, and Jonathan Stieglitz.
Non-technical abstract: Paternal provisioning is ubiquitous in human subsistence societies and unique among apes. How could paternal provisioning have emerged from promiscuous or polygynous mating systems that characterize other apes? An anomalous provisioning male would encounter a social dilemma: Since this investment in prospective offspring can be expropriated by other males, this investment is unlikely to increase the provisioner’s fitness. We present an ecological theory of the evolution of human paternal investment. Ecological change favoring reliance on energetically rich, difficult-to-acquire resources increases payoffs to paternal provisioning due to female–male and/or male–male complementarities. Paternal provisioning becomes a viable reproductive strategy when complementarities are strong, even under high paternity uncertainty. This model illuminates additional paths for understanding the evolution of fatherhood.
- Media coverage: Forbes, Science & Vie
‣ Does informal risk sharing induce lower efforts? Evidence from lab-in-the-field experiments in rural Mexico. Economic Development and Cultural Change Vol. 69, 2020, 107-171. With Laura Juarez, Miriam Juarez-Torres, and Josepa Miquel-Florensa.
Non-technical abstract: There is evidence that informal transfers in developing countries have a negative impact on investment and productive efforts. This article reports results based on experimental data collected in villages of self-subsisting farmers in Mexico. The data allowed us to analyze how the anticipation of giving or receiving transfers affect real effort choices. We find that on average, subjects either make the same or a slightly higher productive effort when they face potential transfers than when no transfers are involved (and the effort thus has an effect only on the subject him- or herself). The study uses a novel experimental design, which presents the advantage of involving no income effects and of enabling study of real effort choices in payoff-equivalent tasks which differ only in whether transfers occur or not.
‣ Evolution of preferences in group-structured populations: genes, guns, and culture. Journal of Economic Theory Vol.185, 2020, 104951. With Jörgen W. Weibull and Laurent Lehmann.
Non-technical abstract: Although moral values have been part of human thinking for thousands of years, economists have tended to disregard this. Our model examines the evolutionary foundations of moral values. It leads to two main results. First, when individuals reflect on the consequences of their actions on fitnesses, a combination of self-interest and a particular kind of Kantian moral (non-consequentialistic) concern is shown to be compatible with natural selection. Second, when individuals reflect on the consequences of their actions on material payoffs, a combination of self-interest, a (non-consequentialistic) Kantian moral concern, and a (consequentialistic) concern about the others' material payoffs is shown to be compatible with natural selection. The (consequentialistic) concern may be either pro-social (altruism) or anti-social (spite). The article builds on our earlier work (see the article published in Evolution in 2015). It combines the “island model”, a classic model used by evolutionary biologists to study the effects of population structure, with game theory and classic models of preference evolution in economics, to examine which preferences cannot be displaced by other strategies once they have become prevalent in a population.
‣ Morality: evolutionary foundations and economic implications. in Basu, K., D. Rosenblatt, and C. Sepulveda, eds., 2020, The State of Economics, the State of the World, Cambridge: MIT Press. With Jörgen W. Weibull.
Non-technical abstract: This book chapter was written for the conference on “The State of Economics, the State of the World,” organized in June 2016 by Kaushik Basu (Chief Economist of the World Bank), to which Jörgen had been invited together with Philippe Aghion, Kenneth Arrow, Guillermo Calvo, Esther Duflo, Amartya Sen, Hyun Song Shin, Nicholas Stern, Joseph Stiglitz, and Cass Sunstein. The chapter summarizes our research on the evolutionary foundations of homo moralis preferences, and discusses some implications of such moral preferences for economic policy.
‣ Evolution of the family: theory and implications for economics. In Oxford Research Encyclopedia of Economics and Finance, November 2019. Oxford University Press. With Donald Cox.
Non-technical abstract: Which parent can be expected to be more altruistic toward their child, the mother or father? All else equal, can we expect older generation members to be more solicitous of younger family members or vice versa? Policy interventions often target recipients by demographic status: more money being put in the hands of mothers, say, or transfers of income from young to old via public pensions. Economics makes predictions about pecuniary incentives and behavior but tends to be agnostic about how, say, a mother might behave, just because she is a mother. Evolutionary theory fills this gap by analyzing how preferences of family members emerge from the Darwinian exigencies of “survive and reproduce.” The article discusses several implications for economics. Moroever, an original case study is provided, which explains the puzzle of diverging marriage rates by education in terms of heterogeneity in preferences for commitment.
‣ Evolutionary models of preference formation. Annual Review of Economics Vol.11, 2019, 329-354. With Jörgen W. Weibull.
Non-technical abstract: This article reviews the theoretical literature on the evolution of preferences that guide behavior in strategic interactions.
‣ Strategic behavior of moralists and altruists. Games Vol. 8(3), 38, 2017. With Jörgen W. Weibull.
Non-technical abstract: In our Econometrica (2013) article (see also the article in Games and Economic Behavior, 2016), we proposed a model of preference evolution in strategic interactions in which the mathematics led to a certain utility function that has hitherto not been studied in economics. Our analysis showed that this utility function is the only one which is evolutionarily stable for the entire set of strategic interactions that we consider. In this article, we study the behavior of such homo moralis preferences in a variety of interactions, such as the one-shot prisoners’ dilemma, a two-player infinitely repeated investment game, and n-player coordination games. We compare behavior of homo moralis to that of individuals equipped with altruistic preferences.
‣ Evolution and Kantian morality. Games and Economic Behavior Vol. 98, 2016, 56-67. With Jörgen W. Weibull.
Non-technical abstract: This article examines extends the analysis of the Econometrica (2013) article (see below) to the case of n-player interactions.
‣ Does evolution lead to maximizing behavior? Evolution Vol. 69, 2015, 1858-1873. With Laurent Lehmann and Jörgen W. Weibull.
Non-technical abstract: This article combines the “island model”, a classic model used by evolutionary biologists to study the effects of population structure, with game theory to examine whether strategies that cannot be displaced by other strategies once they have become prevalent in a population, can be viewed as emanating from individual utility-maximizing behavior.
‣ Homo moralis — preference evolution under incomplete information and assortative matching. Econometrica Vol. 81, 2013, 2269-2302. [Extensive Working Paper version] With Jörgen W. Weibull.
Non-technical abstract: This article examines the evolutionary viability of preferences that guide behavior in strategic interactions involving two individuals (such as public goods games, prisoner’s dilemmas, coordination games, common pool resource games, etc). The mathematical analysis leads to a class of preferences that has not been studied before in economics. We call these preferences homo moralis, since one possible interpretation of this class of preferences is that it induces its carrier to evaluate each strategy not only in light of the material payoff (s)he would obtain from using this strategy, but also in light of the material payoff (s)he would obtain if, hypothetically, the other player were to use this strategy. This Kantian-flavored motive receives a weight that reflects the probability with which rare mutants would get to interact. The intuition is that such preferences induce their carriers to play a strategy that would maximize the fitness of rare mutants; in other words, when most people in a population have homo moralis preferences, equilibrium play preempts entry by other preferences.
- Media coverage: Dagens Nyheter (in Swedish)
‣ The evolution of altruistic preferences: mothers versus fathers. Review of Economics of the Household Vol. 11, 2013, 421-446. With Donald Cox.
Non-technical abstract: This article reviews the theoretical literature on the evolutionary roots of preferences driving parental care, with a focus on factors that may have led these preferences to differ between mothers and fathers.
- Media coverage: Psychology Today
‣ Experience benefits and firm organization. B.E. Journal of Economic Analysis & Policy Vol. 12: Issue 1 (Contributions), Article 39, 2012. With Ching-to Albert Ma and Régis Renault.
Non-technical abstract: This article examines the trade-offs that a firm faces when it chooses between hiring employees and outsourcing work to independent entrepreneurs. On the one hand, the firm faces less severe information problems with in-house production than with outsourcing, but on the other hand it can extract more of the rent associated with on-the-job experience from under outsourcing than under in-house production.
‣ A generalization of Hamilton's rule — Love others how much? Journal of Theoretical Biology Vol. 299, 2012, 42-54. [Click here for illustrating plots (due to Kristaps Dzonsons)] With Jörgen W. Weibull.
Non-technical abstract: Suppose that the extent to which individuals care for other’s material well-being (as captured by their “degree of altruism”) is a preference trait that is transmitted from parents to children. The article shows that evolution by natural selection may then have led the degree of altruism to depend on the specifics of the interaction. In particular, if the interaction involves strategic complementarities, an evolutionarily stable degree of altruism is higher than if it involves strategic substitutabilities.
‣ Public goods games, altruism, and evolution. Journal of Public Economic Theory Vol. 12, 2010, 789-813.
Non-technical abstract: Suppose that the extent to which individuals care for other’s material well-being (as captured by their “degree of altruism”) is a preference trait that is transmitted from parents to children. The article shows that evolution by natural selection may then have led the degree of altruism to depend on the specifics of the interaction. The model focuses on interactions with strategic substitutabilities between the individuals’ strategies.
‣ Kinship, incentives and evolution. American Economic Review Vol. 100, 2010, 1725-1758. With Jörgen W. Weibull.
Non-technical abstract: Suppose that the strength of family ties (as captured by intra-family altruism and the associated amount of helping behaviors within families) is transmitted from parents to children. The article shows that evolution by natural selection may then have led the strength of family ties to differ across different parts of the world in in pre-industrial agricultural societies. In particular, the model predicts that weaker family ties are to be expected in harsher environments.
‣ Family ties, incentives and development: a model of coerced altruism. in Basu, K., and R. Kanbur, eds., 2008, Arguments for a Better World: Essays in Honor of Amartya Sen, Volume II: Society, Institutions and Development, Oxford: Oxford University Press. With Jörgen W. Weibull.
Non-technical abstract: In many countries a social norm requires a relatively wealthy individual to help his/her poorer relatives. The book chapter shows that such “kin taxes” either weaken or strengthen an individual’s incentive to provide productive efforts, depending on whether the norm is in line with the individual’s intrinsic preferences.
‣ Screening ethics when honest agents keep their word. Economic Theory Vol. 30, 2007, 291-311. With Régis Renault.
Non-technical abstract: Some individuals are unwilling to misrepresent their private information. The article formalizes a kind of “honesty” in an otherwise standard principal-agent model, and shows that it provides a rationale for contracts that request the agent to report non-verifiable information.
‣ A theory of fraud and over-consumption in experts markets. Journal of Economics, Management & Strategy Vol. 15, 2006, 853-881. With François Salanié.
Non-technical abstract: Experts (such as mechanics, dentists, physicians, and lawyers) may be tempted to over-treat their customers if the prices they charge give them an incentive to do so; by characterizing equilibrium prices in a competitive experts market, the article identifies conditions that lead to equilibrium over-treatment.
‣ Screening ethics when honest agents care about fairness. International Economic Review Vol. 47, 2006, 59-85. With Régis Renault.
Non-technical abstract: Some individuals are unwilling to misrepresent their private information. The article formalizes several forms of “honesty” in an otherwise standard principal-agent model, and shows that some forms of honesty are more exploitable than others.
‣ Moral hazard, insurance, and some collusion. Journal of Economic Behavior and Organization Vol. 50, 2003, 225-247. With Ching-to Albert Ma.
Non-technical abstract: Fraudulent insurance claims can be deterred with adequate contract design; the article investigates contract design when only some customers would consider defrauding the insurer.
‣ Consumer strategies limiting the monopolist's power: multiple and joint purchases. RAND Journal of Economics Vol. 30, 1999, 736-757.
Non-technical abstract: The classic models of second-degree price discrimination (Maskin and Riley, 1984, Mussa and Rosen, 1978) rely on the assumption that consumers cannot purchase multiple "bundles" or make joint purchases of bundles. This article lifts this assumption. This leads to an original and intuitive rationale for quantity discounts.
DORMANT PAPERS
‣ Liquid assets in banks: theory and practice (with Guillermo Alger) [WP Boston College 446]
‣ Optimal debt contracts when credit managers are (perhaps) corruptible [WP Boston College 648]
RESEARCH STATEMENT
Economics research has traditionally focused on understanding how---for a given distribution of preferences---market performance, supply, demand, and prices depend on factors such as the degree of competition, the available technology, market frictions such as asymmetric information, and institutional factors such as the distribution of property rights and contract enforcement.
In my research I adopt a complementary approach, by asking: which preferences should one expect to see in a population in which preferences have been transmitted from generation to generation, and where preferences affect the ability of individuals to survive and transmit their preferences (biologically or culturally)?
Answers are sought by way of using simple evolutionary logic: those alive today had ancestors who were successful at surviving and reproducing; conditional on preferences being transmitted from old to young (through vertical or oblique transmission), this means that our preferences should reflect this.
Evolutionary logic in turn means that factors in the environment in which a population evolves may impact which behaviors lead to evolutionary success, and thus also which preferences are more successful than others. The overarching objective of my research is to contribute to the understanding of the factors in our evolutionary past that may thus have shaped our preferences as well as our family structures and intra-family behaviors.
Specifically, in my research I have worked on the following questions:
(1) Evolutionary foundations of preferences:
(2) Some of my work focuses on the implications of certain preferences, in particular a preference for honesty and altruistic preferences:
(3) Finally, I have done some work in industrial organization:
Economics research has traditionally focused on understanding how---for a given distribution of preferences---market performance, supply, demand, and prices depend on factors such as the degree of competition, the available technology, market frictions such as asymmetric information, and institutional factors such as the distribution of property rights and contract enforcement.
In my research I adopt a complementary approach, by asking: which preferences should one expect to see in a population in which preferences have been transmitted from generation to generation, and where preferences affect the ability of individuals to survive and transmit their preferences (biologically or culturally)?
Answers are sought by way of using simple evolutionary logic: those alive today had ancestors who were successful at surviving and reproducing; conditional on preferences being transmitted from old to young (through vertical or oblique transmission), this means that our preferences should reflect this.
Evolutionary logic in turn means that factors in the environment in which a population evolves may impact which behaviors lead to evolutionary success, and thus also which preferences are more successful than others. The overarching objective of my research is to contribute to the understanding of the factors in our evolutionary past that may thus have shaped our preferences as well as our family structures and intra-family behaviors.
Specifically, in my research I have worked on the following questions:
(1) Evolutionary foundations of preferences:
- Can evolution by natural selection lead to moral values?
- Can evolution have led to weaker family ties in some parts of the world than in others in pre-industrial societies?
- If individuals have altruistic preferences, what is the degree of altruism that evolution should be expected to lead to?
- Should mothers be expected to more altruistic than fathers towards their children?
- Should men be expected to always want to have more wives if they want to maximize reproductive success?
- Which factors facilitated the evolution of paternal investment in our species, a behavior which is rarely found in mammals?
(2) Some of my work focuses on the implications of certain preferences, in particular a preference for honesty and altruistic preferences:
- Should we expect helping behaviors to be detrimental to work effort?
- How can we define honesty in economics models, and how does honesty affect contracts within firms?
- Why does competition among sellers who provide advice to consumers not necessarily lead them to behave honestly?
(3) Finally, I have done some work in industrial organization:
- How can experience benefits affect firm organization?
- Why do firms offer quantity discounts?
