A model is presented to account for the natural selection of what is termed reciprocally altruistic behavior. The model shows how selection can operate -against the cheater (non-reciprocator) in the system. Three instances of altruistic behavior are discussed, the evolution of which the model can explain: (1) behavior involved in cleaning symbioses; (2) warning cries in birds: and (3) human reciprocal altruism. Regarding human reciprocal altruism, it is shown that the details of the psychological system that regulates this altruism can (...) be explained by the model. Specifically, friendship,d islike, moralistic aggression, gratitude, sympathy, trust, suspicion, trustworthiness, aspects of guilt, and some forms of dishonesty and hypocrisy can be explained as important adaptations to regulate the altruistic system. Each individual human is seen as possessing altruistic and cheating tendencies, the expression of which is sensitive to developmental variables that were selected to set the tendencies at a balance appropriate to the local social and ecological environment. (shrink)

The authors demonstrate that unselfish behavior is in fact an important feature of both biological and human nature. Their book provides a panoramic view of altruism throughout the animal kingdom--from self-sacrificing parasites to the human capacity for selflessness--even as it explains the evolutionary sense of such behavior.

The Ultimatum Game is one of the most successful experimental designs in the history of the social sciences. In this article I try to explain this success—what makes it a “paradigmatic experiment”—stressing in particular its versatility. Despite the intentions of its inventors, the Ultimatum Game was never a good design to test economic theory, and it is now mostly used as a heuristic tool for the observation of nonstandard preferences or as a “social thermometer” for the observation of culture‐specific norms. (...) †To contact the author, please write to: Department of Sociology and Philosophy, University of Exeter, Amory Building, Exeter EX4 4DT, UK; e‐mail: [email protected]. (shrink)

What sort of claims do scientific models make and how do these claims then underwrite empirical successes such as explanations and reliable policy interventions? In this paper I propose answers to these questions for the class of models used throughout the social and biological sciences, namely idealized deductive ones with a causal interpretation. I argue that the two main existing accounts misrepresent how these models are actually used, and propose a new account. *Received July 2006; revised August 2008. †To contact (...) the author, please write to: Department of Philosophy, University of Missouri, St. Louis, 599 Lucas Hall (MC 73), One University Blvd., St. Louis, MO 63121-4400; e-mail: [email protected]. (shrink)

What motives underlie the ways humans interact socially? Are these the same for all societies? Are these part of our nature, or influenced by our environments?Over the last decade, research in experimental economics has emphatically falsified the textbook representation of Homo economicus. Literally hundreds of experiments suggest that people care not only about their own material payoffs, but also about such things as fairness, equity and reciprocity. However, this research left fundamental questions unanswered: Are such social preferences stable components of (...) human nature; or, are they modulated by economic, social and cultural environments? Until now, experimental research could not address this question because virtually all subjects had been university students, and while there are cultural differences among student populations throughout the world, these differences are small compared to the full range of human social and cultural environments. A vast amount of ethnographic and historical research suggests that people's motives are influenced by economic, social, and cultural environments, yet such methods can only yield circumstantial evidence about human motives. Combining ethnographic and experimental approaches to fill this gap, this book breaks new ground in reporting the results of a large cross-cultural study aimed at determining the sources of social preferences that underlie the diversity of human sociality. The same experiments which provided evidence for social preferences among university students were performed in fifteen small-scale societies exhibiting a wide variety of social, economic and cultural conditions by experienced field researchers who had also done long-term ethnographic field work in these societies. The findings of these experiments demonstrated that no society in which experimental behaviour is consistent with the canonical model of self-interest. Indeed, results showed that the variation in behaviour is far greater than previously thought, and that the differences between societies in market integration and the importance of cooperation explain a substantial portion of this variation, which individual-level economic and demographic variables could not. Finally, the extent to which experimental play mirrors patterns of interaction found in everyday life is traced.The book starts with a succinct but substantive introduction to the use of game theory as an analytical tool and its use in the social sciences for the rigorous testing of hypotheses about fundamental aspects of social behaviour outside artificially constructed laboratories. The results of the fifteen case studies are summarized in a suggestive chapter about the scope of the project. (shrink)

Human cooperation is held to be an evolutionary puzzle because people voluntarily engage in costly cooperation, and costly punishment of non-cooperators, even among anonymous strangers they will never meet again. The costs of such cooperation cannot be recovered through kin-selection, reciprocal altruism, indirect reciprocity, or costly signaling. A number of recent authors label this behavior ‘strong reciprocity’, and argue that it is: (a) a newly documented aspect of human nature, (b) adaptive, and (c) evolved by group selection. We argue exactly (...) the opposite; that the phenomenon is: (a) not new, (b) maladaptive, and (c) evolved by individual selection. In our perspective, the apparent puzzle disappears to reveal a biological and evolutionary logic to human cooperation. Group selection may play a role in theory, but it is neither necessary nor sufficient to explain human cooperation. Our alternative solution is simpler, makes fewer assumptions, and is more parsimonious with the empirical data. (shrink)

The 'Evolution of Cooperation' addresses a simple yet age-old question; If living things evolve through competition, how can cooperation ever emerge? Despite the abundant evidence of cooperation all around us, there existed no purely naturalistic answer to this question until 1979, when Robert Axelrod famously ran a computer tournament featuring a standard game-theory exercise called The Prisoner's Dilemma. To everyone's surprise, the program that won the tournament, named Tit for Tat, was not only the simplest but the most "cooperative" entrant. (...) This unexpected victory proved that cooperation - one might even say altruism - is mathematically possible and therefore needs no hidden hand or divine agent to create and sustain it. A great roadblock to the understanding of all sorts of behavior was at last removed. The updated edition includes an extensive new chapter on cooperation in cancer cells and among terrorist organizations. (shrink)

The problem of moral compliance is the problem of explaining how moral norms are sustained over extented stretches of time despite the existence of selfish evolutionary incentives that favor their violation. There are, broadly speaking, two kinds of solutions that have been offered to the problem of moral compliance, the reciprocity-based account and the punishment-based account. In this paper, I argue that though the reciprocity-based account has been widely endorsed by evolutionary theorists, the account is in fact deeply implausible. I (...) provide three arguments that suggest that moral norms are sustained by punishment, not reciprocity. But in addition to solving the problem of moral compliance, the punishment-based account provides an additional important theoretical dividend. It points the way for how theorists might build an evolutionary account of a feature of human groups that has long fascinated and troubled social scientists and moral philosophers – the existence of moral diversity. (shrink)

Acknowledgments 1. Culture Is Essential 2. Culture Exists 3. Culture Evolves 4. Culture Is an Adaptation 5. Culture Is Maladaptive 6. Culture and Genes Coevolve 7. Nothing about Culture Makes Sense except in the Light of Evolution.

The experimental approach in economics is a driving force behind some of the most exciting developments in the field. The 'experimental revolution' was based on a series of bold philosophical premises which have remained until now mostly unexplored. This book provides the first comprehensive analysis and critical discussion of the methodology of experimental economics, written by a philosopher of science with expertise in the field. It outlines the fundamental principles of experimental inference in order to investigate their power, scope and (...) limitations. The author demonstrates that experimental economists have a lot to gain by discussing openly the philosophical principles that guide their work, and that philosophers of science have a lot to learn from their ingenious techniques devised by experimenters in order to tackle difficult scientific problems. (shrink)

In the past decade, experiments on altruistic punishment have played a central role in the study of the evolution of cooperation. By showing that people are ready to incur a cost to punish cheaters and that punishment help to stabilise cooperation, these experiments have greatly contributed to the rise of group selection theory. However, despite its experimental robustness, it is not clear whether altruistic punishment really exists. Here, I review the anthropological literature and show that hunter-gatherers rarely punish cheaters. Instead, (...) they avoid dealing with them and switch to other partners. I suggest that these data are better explained by individual selection, and in particular by partner choice models, in which individuals are in competition to be recruited by cooperative partners. I discuss two apparent problems for partner choice theories: large-scale cooperation and punishments in economic games. I suggest that rather than favouring group selection theory, these two phenomena provide evidence in favour of individual selection: (1) people produce large-scale cooperation through institutions in which punishment is not altruistic but rewarded on an individual basis; (2) punishment in experimental games can be explained without altruism and is indeed often better explained by individual interests. (shrink)

Inferences like these are known as extrapolations.

Natural Justice is a bold attempt to lay the foundations for a genuine science of morals using the theory of games. Since human morality is no less a product of evolution than any other human characteristic, the book takes the view that we need to explore its origins in the food-sharing social contracts of our prehuman ancestors. It is argued that the deep structure of our current fairness norms continues to reflect the logic of these primeval social contracts, but the (...) particular fairness norm a society operates is largely a product of cultural evolution. In pursuing this point, the book proposes a naturalistic reinterpretation of John Rawls' original position that reconciles his egalitarian theory of justice with John Harsanyi's utilitarian theory by identifying the environment appropriate to each. (shrink)

Can people be relied upon to be nice to each other? Thomas Hobbes famously did not think so, but his view that rational cooperation does not require that people be nice has never been popular. The debate has continued to simmer since Joseph Butler took up the Hobbist gauntlet in 1725. This article defends the modern version of Hobbism derived largely from game theory against a new school of Butlerians who call themselves behavioral economists. It is agreed that the experimental (...) evidence supports the claim that most people will often make small sacrifices on behalf of others and that a few will sometimes make big sacrifices, but that the larger claims made by contemporary Butlerians lack genuine support. (shrink)

This article surveys some of the philosophical issues raised by recent experimental work in economics on so-called social preferences. This work raises a number of fascinating methodological and interpretive issues that are of central importance both to economics and to social and political philosophy.

In this article, I critically respond to Herbert Gintis's criticisms of the behavioral-economic foundations of Ken Binmore 's game-theoretic theory of justice. Gintis, I argue, fails to take full account of the normative requirements Binmore sets for his account, and also ignores what I call the ‘scale-relativity’ considerations built into Binmore 's approach to modeling human evolution. Paul Seabright's criticism of Binmore, I note, repeats these oversights. In the course of answering Gintis's and Seabright's objections, I clarify and extend Binmore (...) 's theory in a number of respects, integrating it with Kim Sterelny's and Don Ross's recent work on the evolution of people as cultural entities. The account also yields a novel basis for choosing between socialism and what Binmore calls ‘whiggery’ as normative political programs. Key Words: theory of justice • bargaining theory • evolutionary game theory • human evolution • Ken Binmore • Herbert Gintis • Kim Sterelny. (shrink)

In this book, I make use of an idea from economics to suggest how noble human tendencies might not only have survived the ruthless pressures of the material world, but actually have been nurtured by them.

The authors explore the history of experiments in economics, provide examples of different types of experiments and show that the growing use of experimental methods is transforming economics into an empirical science.

The recent literature on social norms has stressed the centrality of emotions in explaining punishment and norm enforcement. This article discusses four negative emotions (righteous anger, indignation, contempt, and disgust) and examines their relationship to punitive behavior. I argue that righteous anger and indignation are both punitive emotions strictly speaking, but induce punishments of different intensity and have distinct elicitors. Contempt and disgust, for their part, cannot be straightforwardly considered punitive emotions, although they often blend with a colder form of (...) indignation to favor low-cost, indirect, and collective forms of punishment such as mockery, exclusion, and ostracism. (shrink)

offers an evolutionary approach to morality, in which moral rules form a cultural system that is robust and evolutionarily stable. The folk theorem is the analytical basis for his theory of justice. I argue that this is a mistake, as the equilibria described by the folk theorem lack dynamic stability in games with several players. While the dependence of Binmore's argument on the folk theorem is more tactical than strategic, this choice does have policy implications. I do not believe that (...) moral rules are solutions to the Nash bargaining problem. Rather, I believe that human beings are emotionally constituted, by virtue of their evolutionary history, to embrace prosocial and altruistic notions of in-group–out-group identification and reciprocity. These aspects of human nature are incompatible with Binmore's notion that humans are self-regarding creatures. I present empirical evidence supporting a specific form of human, other-regarding preferences known as strong reciprocity. Key Words: justice • ethics • folk theorem • evolutionary game theory. (shrink)

The concept of cooperative communities that enforce norm conformity through reward, as well as shaming, ridicule, and ostracism, has been central to anthropology since the work of Durkheim. Prevailing approaches from evolutionary theory explain the willingness to exert sanctions to enforce norms as self-interested behavior, while recent experimental studies suggest that altruistic rewarding and punishing—“strong reciprocity”—play an important role in promoting cooperation. This paper will use data from 308 conversations among the Ju/’hoansi (!Kung) Bushmen (a) to examine the dynamics of (...) norm enforcement, (b) to evaluate the costs of punishment in a forager society and understand how they are reduced, and (c) to determine whether hypotheses that center on individual self-interest provide sufficient explanations for bearing the costs of norm enforcement, or whether there is evidence for strong reciprocity. (shrink)

Robert Boyd*†, Herbert Gintis‡, Samuel Bowles§, and Peter J. Richerson¶.

The transfer of food among group members is a ubiquitous feature of small-scale forager and forager-agricultural populations. The uniqueness of pervasive sharing among humans, especially among unrelated individuals, has led researchers to evaluate numerous hypotheses about the adaptive functions and patterns of sharing in different ecologies. This article attempts to organize available cross-cultural evidence pertaining to several contentious evolutionary models: kin selection, reciprocal altruism, tolerated scrounging, and costly signaling. Debates about the relevance of these models focus primarily on the extent (...) to which individuals exert control over the distribution of foods they acquire, and the extent to which donors receive food or other fitness-enhancing benefits in return for shares given away. Each model can explain some of the variance in sharing patterns within groups, and so generalizations that ignore or deny the importance of any one model may be misleading. Careful multivariate analyses and cross-cultural comparisons of food transfer patterns are therefore necessary tools for assessing aspects of the sexual division of labor, human life history evolution, and the evolution of the family. This article also introduces a framework for better understanding variation in sharing behavior across small-scale traditional societies. I discuss the importance of resource ecology and the degree of coordination in acquisition activities as a key feature that influences sharing behavior. (shrink)

Many weaknesses of game theory are cured by new models that embody simple cognitive principles, while maintaining the formalism and generality that makes game theory useful. Social preference models can generate team reasoning by combining reciprocation and correlated equilibrium. Models of limited iterated thinking explain data better than equilibrium models do; and they self-repair problems of implausibility and multiplicity of equilibria.

Recent developments in evolutionary game theory argue the superiority of punishment over reciprocity as accounts of large-scale human cooperation. I introduce a distinction between a behavioral and a psychological perspective on reciprocity and punishment to question this view. I examine a narrow and a wide version of a psychological mechanism for reciprocity and conclude that a narrow version is clearly distinguishable from punishment, but inadequate for humans; whereas a wide version is applicable to humans but indistinguishable from punishment. The mechanism (...) for reciprocity in humans emerges as a meta-norm that governs both retaliation and punishment. I make predictions open to empirical investigation to confirm or disconfirm this view. (shrink)

With an interest in origins, it is proposed that conflict within the group can be taken as a natural focus for exploring the evolutionary development of human moral communities. Morality today involves social control but also the management of conflicts within the group. It is hypothesized that early manifestations of morality involved the identification and collective suppression of behaviours likely to cause such conflict. By triangulation the mutual ancestor of humans and the two Pan species lived in pronounced social dominance (...) hierarchies, and made largely individualized efforts to damp conflict within the group, exhibiting consolation, reconciliation, and active pacifying intervention behaviour. It is particularly the active interventions that can be linked with social control as we know it. It is proposed that when this process became collectivized, and when language permitted the definition and tracking of proscribed behaviour, full-blown morality was on its way. Because early humans lived in egalitarian bands, a likely candidate for the first behaviour to be labelled as morally deviant is not the incest taboo but bullying behaviour, of the type that egalitarian humans today universally proscribe and suppress. (shrink)

The principal findings of experimental economics are that impersonal exchange in markets converges in repeated interaction to the equilibrium states implied by economic theory, under information conditions far weaker than specified in the theory. In personal, social, and economic exchange, as studied in two-person games, cooperation exceeds the prediction of traditional game theory. This book relates these two findings to field studies and applications and integrates them with the main themes of the Scottish Enlightenment and with the thoughts of F. (...) A. Hayek. (shrink)