Big Ideas for Little Kids includes everything a teacher, a parent, or a college student needs to teach philosophy to elementary school children from picture books. Written in a clear and accessible style, the book explains why it is important to allow young children access to philosophy during primary-school education. Wartenberg also gives advice on how to construct a "learner-centered" classroom, in which children discuss philosophical issues with one another as they respond to open-ended questions by saying whether they agree (...) or disagree with what others have said. (shrink)

This volume gives an overview of the rising field of Experimental Ethics. It is organized into five main parts: PART I – Introduction: An Experimental Philosophy of Ethics? // PART II – Applied Experimental Ethics: Case studies // PART III – On Methodology // PART IV – Critical Reflections // PART V – Future Perspectives. Among the contributors: Walter Sinnott-Armstrong, Eric Schwitzgebel, Ezio di Nucci, Jacob Rosenthal, and Fernando Aguiar.

Recent years have seen a continual rise of interest in the empirical study of questions traditionally located in moral philosophy, i.e., studies in Experimental Ethics. In this chapter we briefly outline the recent history of this field. To do so we have to cross disciplinary borders to quite some extent. Tracing the beginnings of Experimental Ethics back to early works in moral psychology, we delineate a sequence of theories which eventually flow into current Experimental Ethics. We then briefly review four (...) topics which are intensively investigated in Experimental Ethics at the moment: moral relativism, individual and cross-cultural differences in moral judgment, and interactions of moral evaluation with other philosophical concepts. We conclude with a short historically informed comment on the demarcation problem of Experimental Ethics. (shrink)

L'" action " est aujourd'hui un concept clé de la philosophie et de la plupart des sciences humaines. Dans toutes ces disciplines (économie, psychologie, sociologie), la formulation d'une " théorie de l'action " constitue l'un des principaux centres d'intérêt de la réflexion théorique. Ce livre développe une idée centrale : aux deux modèles dominants de l'action rationnelle et de l'action à visée normative, il est possible d'en ajouter un troisième, qui insiste sur le caractère créatif de l'agir humain. Ce troisième (...) modèle doit avoir une position englobante par rapport aux deux premiers. Il s'agit de mettre au jour dans tout agir humain une dimension créative qui n'est pas suffisamment prise en compte dans les modèles théoriques de l'action rationnelle et de l'action à visée normative. Cette approche, en effet, n'oppose pas aux actes créatifs les actes non créatifs, mais cherche à préciser les conditions d'application des deux modèles courants, en mettant en évidence la dimension créatrice qui s'y trouve implicitement contenue. Les différentes parties de l'ouvrage (étude de l'histoire des idées, reconstruction théorique des concepts, leur application concrète) servent toutes un but commun : montrer qu'il est pertinent et nécessaire de prendre en considération le caractère créateur de l'agir humain. (shrink)

v. 1. Editorial introduction -- v. 2. The English and Latin texts (i) -- v. 3. The English and Latin texts (ii).

Although humans qualify as one of the most cooperative animal species, the scale of violent intergroup conflict among them is unparalleled. Explanations of the underlying motivations to participate in an intergroup conflict, however, remain unsatisfactory. While previous research shows that intergroup conflict increases individually costly behavior to the benefit of the in-group, it has failed to identify robust triggers of aggressive behavior directed at out-groups. Here, we present a controlled laboratory experiment which demonstrates that such aggression can be provoked systematically (...) by manipulating the extent to which the own group is perceived to be on the offensive or the defensive side of a conflict. We find direct and causal evidence that the motivation to protect the in-group is not only a predictor of retaliatory aggression, but also promotes preemptive offensive actions against out-groups if they pose a potential threat. This finding improves our understanding of the escalation of intergroup conflicts and may have important implications for their prevention, as we find in our experiment that removing out-group threat substantially reduced intergroup aggression and led to full peace. (shrink)

Although humans qualify as one of the most cooperative animal species, the scale of violent intergroup conflict among them is unparalleled. Explanations of the underlying motivation to participate in an intergroup conflict, however, remain unsatisfactory. While previous research shows that intergroup conflict increases ‘in-group love’, it fails to identify robust triggers of ‘out-group hate’. Here, we present a controlled laboratory experiment, which demonstrates that ‘out-group hate’ can be provoked systematically. We find direct and causal evidence that the intention to protect (...) the in-group is not only a crucial motivator of ‘out-group hate’ in defensive reactions, but also promotes preemptive offensive actions against out-group threat. Hence, the strength of ‘out-group hate’ depends on whether the own group is perceived to be on the offensive or the defensive side of the conflict. This finding improves our understanding of the escalation of intergroup conflicts and may have important implications for their prevention, as we find in our experiment that removing out-group threat substantially reduces intergroup aggression, leading to full peace. (shrink)

In evolutionary models of indirect reciprocity, reputation mechanisms can stabilize cooperation even in severe cooperation problems like the prisoner’s dilemma. Under certain circumstances, conditionally cooperative strategies, which cooperate iff their partner has a good reputation, cannot be invaded by any other strategy that conditions behavior only on own and partner reputation. The first point of this paper is to show that an evolutionary version of backward induction can lead to a breakdown of this kind of indirectly reciprocal cooperation. Backward induction, (...) however, requires strategies that count and then cease to cooperate in the last, last but one, last but two, … game they play. These strategies are unlikely to exist in natural settings. We then present two new findings. (1) Surprisingly, the same kind of breakdown is also possible without counting. Strategies using rare golden opportunities for defection can invade conditional cooperators. This can create further golden opportunities, inviting the next wave of opportunists, and so on, until cooperation breaks down completely. (2) Cooperation can be stabilized against these opportunists, by letting an individual’s initial reputation be inherited from that individual’s parent. This ‘inclusive reputation’ mechanism can cope with any observably opportunistic strategy. Offspring of opportunists who successfully exploited a conditional cooperator cannot repeat their parents’ success because they inherit a bad reputation, which forewarns conditional cooperators in later generations. (shrink)

Si la " critique philosophique de l'art " peut constituer l'axe central d'une approche de la pensée de Walter Benjamin, c'est d'abord parce que l'art représente l'élément par lequel l'homme accède à sa propre temporalité. Le passé individuel, l'origine commune, le projet militant se cristallisent dans le geste artistique. La mémoire elle-même est une forme d'art, non moins que l'anticipation d'un avenir désirable. Investi du pouvoir de définir ainsi l'humanité de l'homme, l'art devient éminemment critiquable : Benjamin n'a jamais cru (...) que pratiquer la " critique " dispensât d'être philosophe. La critique, au contraire, n'a d'autre lieu que la philosophie, sous sa forme la plus épurée. On touche ici du doigt le fascinant pouvoir intégrateur de la pensée benjaminienne, capable de conjuguer l'autobiographique et le politique, la précision analytique et l'élan éthique, la déconstruction et la métaphysique. Quand Benjamin a été si souvent morcelé en personnalités contradictoires, sous la plume parfois d'un seul et même commentateur, c'est une image très cohérente, très homogène, qui nous semble ressortir des diverses contributions de ce recueil. (shrink)

This paper is an exposition and evaluation of the Agustín Rayo's views about the epistemology and metaphysics of mathematics, as they are presented in his book The Construction of Logical Space.

Drawing on an idea proposed by Darwin, it has recently been hypothesised that violent intergroup conflict might have played a substantial role in the evolution of human cooperativeness and altruism. The central notion of this argument, dubbed ‘parochial altruism’, is that the two genetic or cultural traits, aggressiveness against out-groups and cooperativeness towards the in-group, including self-sacrificial altruistic behaviour, might have coevolved in humans. This review assesses the explanatory power of current theories of ‘parochial altruism’. After a brief synopsis of (...) the existing literature, two pitfalls in the interpretation of the most widely used models are discussed: potential direct benefits and high relatedness between group members implicitly induced by assumptions about conflict structure and frequency. Then, a number of simplifying assumptions made in the construction of these models are pointed out which currently limit their explanatory power. Next, relevant empirical evidence from several disciplines which could guide future theoretical extensions is reviewed. Finally, selected alternative accounts of evolutionary links between intergroup conflict and intragroup cooperation are briefly discussed which could be integrated with parochial altruism in the future. (shrink)

Building on and partially refining previous theoretical work, this paper presents an extended simulation model of ancestral warfare. This model (1) disentangles attack and defense, (2) tries to differentiate more strictly between selfish and altruistic efforts during war, (3) incorporates risk aversion and deterrence, and (4) pays special attention to the role of brutality. Modeling refinements and simulation results yield a differentiated picture of possible evolutionary dynamics. The main observations are: (i) Altruism in this model is more likely to evolve (...) for defenses than for attacks. (ii) Risk aversion, deterrence and the interplay of migration levels and brutality can change evolutionary dynamics substantially. (iii) Unexpectedly, one occasional simulation outcome is a dynamically stable state of ‘tolerated intergroup theft’, raising the question if corresponding patterns also exist in real intergroup conflicts. Finally, possible implications for theories of the co-evolution of bellicosity and altruism in humans are discussed. (shrink)

This volume is a study of the influence of Timaeus on the development of Western cosmology in three axial periods of European culture: Late Antiquity, Middle Ages and Renaissance.

Comment on Armin Falk & Nora Szech "Morals and Markets", Science 340(6133), 707-711, 2013.

In diesem Artikel stellen wir die Evolutionäre Erkenntnistheorie kurz vor. Wir gehen dazu in zwei Schritten vor: In Schritt 1 charakterisieren wir die Evolutionäre Erkenntnistheorie anhand ihrer Antworten auf die Grundfragen an jede Erkenntnistheorie. In Schritt 2 stellen wir all jene philosophischen Positionen dar, mit denen die Evolutionäre Erkenntnistheorie eng verbunden ist.

It has recently been proposed that the evolution of human cooperativeness might, at least in part, have started as the cooptation of behavioral strategies evolved for solving problems of coordination to solve problems with higher incentives to defect, i.e. problems of cooperation. Following this line of thought, we systematically tested human subjects for spillover effects from simple coordination tasks (2x2 Stag Hunt games, SH) to problems of cooperation (2x2 Prisoner’s Dilemma games, PD) in a laboratory experiment with rigorous controls to (...) rule out subject confusion or habituation. Supporting the hypothesis that decision mechanisms for cooperation problems are linked with decision mechanisms for coordination, our main finding is that cooperation levels in PD games embedded in a sequence of SH games were significantly increased compared to a baseline sequence consisting only of PDs when subjects played in fixed pairs. No such effects could be found when players were randomly rematched each round. Additional findings include that this spillover effect cannot prevent a decay of cooperation over time, that there is no indication of a reversed effect, i.e. no signs of negative spillovers from failed cooperation to miscoordination, and that subjects self-reported preferences in SH games are prosocial. (shrink)

Sind Sie Naturalist, Metaphysikerin oder Rationalist? Existentialistin, Materialist oder Deterministin? Sie wissen es nicht? Der Philomat ist ein Apparat für weltanschauliche Diagnostik. Er sagt Ihnen, wie Sie denken, wenn Sie denken. Er stellt Ihnen Fragen aus ganz alltäglichen Zusammenhängen und ermittelt anhand Ihrer Antworten, welche philosophischen Überzeugungen Ihr Denken leiten. Sie erfahren, wie Ihre ganz persönliche Art zu denken in der Philosophie heißt, welche Konsequenzen mit ihr verbunden sind, welche Philosophen so denken wie Sie und wo Sie Ihre Überzeugungen vertiefen (...) können. (shrink)

In this article we try to give a philosophically reflected introductory overview of the current theoretical developments in the field of evolutionary aesthetics. Our aim is not completeness. Rather, we try to depict some of the central assumptions and explanatory tools frequently used in evolutionary accounts of human aesthetical preferences and address a number of currently debated, open research questions.

Ethics is a field in which the gap between words and actions looms large. Game theory and the empirical methods it inspires look at behavior instead of the lip service people sometimes pay to norms. We believe that this special issue comprises several illustrations of the fruitful application of this approach to ethics.

Thomas Reid is now recognized as one of the towering figures of the Enlightenment. Best known for his published writings on epistemology and moral theory, he was also an accomplished mathematician and natural philosopher, as an earlier volume of his manuscripts edited by Paul Wood for the Edinburgh Reid Edition, Thomas Reid on the Animate Creation, has shown. The Correspondence of Thomas Reid collects all of the known letters to and from Reid in a fully annotated form. (...) Letters already published by Sir William Hamilton and others have been reedited, and roughly half of the letters included appear in print for the first time. Writing in 1802, Reid's disciple and biographer Dugald Stewart doubted that Reid's correspondence &"would be generally interesting.&" This collection proves otherwise, for the letters illuminate virtually every aspect of Reid's life and career and, in some instances, provide us with invaluable evidence about activities otherwise undocumented in his manuscripts or published works. Through his correspondence we can trace Reid's relations with contemporaries such as David Hume and his colleagues at both King's College, Aberdeen, and the University of Glasgow, as well as his engagement with the most controversial philosophical, scientific, and political issues of his day. If anything, the letters assembled here serve as the starting point for understanding Reid and his place in the Enlightenment. (shrink)

Many studies show that punishment, although able to stabilize cooperation at high levels, destroys gains which makes it less efficient than alternatives with no punishment. Standard public goods games (PGGs) in fact show exactly these patterns. However, both evolutionary theory and real world institutions give reason to expect institutions with punishment to be more efficient, particularly in the long run. Long-term cooperative partnerships with punishment threats for non-cooperation should outperform defection prone non-punishing ones. This article demonstrates that fieldwork data from (...) hunter-gatherers, common pool resource management cases and even PGGs support this hypothesis. Although earnings in PGGs with a punishment option may be lower at the beginning, efficiency increases dramatically over time. Most ten-period PGGs cannot capture this change because their time horizon is too short. (shrink)

Depuis l'exil, le philosophe W. Benjamin recompose, dans une sA(c)rie de brA]ves vignettes, ses souvenirs d'enfance A Berlin. Loin de l'anecdote, il s'agit d'une vA(c)ritable plongA(c)e dans l'enfance et dans l'histoire, oA se retrouvent les thA]mes essentiels de la philosophie benjaminienne. Ce texte restA(c) inA(c)dit du vivant de l'auteur, est dA(c)sormais connu en plusieurs variantes, dont celle-ci est la derniA]re A laquelle il ait mis la main. Walter Benjamin (1892-1940) est un philosophe, historien de l'art, critique littA(c)raire, critique d'art et (...) traducteur (notamment de Balzac, Baudelaire et Proust) allemand de la premiA]re moitiA(c) du XXe siA]cle, rattachA(c) A l'A(c)cole de Francfort. Traduction et prA(c)face de Pierre Rusch Postscriptum de Patricia Lavelle. (shrink)

Bankers have a reputation for deviating from standard morals. It is an open question, though, if this claim can be substantiated. Here, it is tested directly if bankers respond differently to moral dilemmas. Evaluations of the moral acceptableness of behavioural options in two trolley cases by bankers (n = 23) are compared to those of ordinary people (n = 274). An apparent difference in response behaviour between the groups can be fully explained by a difference in the response behaviour of (...) men and women. When controlling for gender, no differences between bankers and other people remain. (shrink)

We report three studies which test a sexual selection hypothesis for male war heroism. Based on evolutionary theories of mate choice we hypothesize that men signal their fitness through displaying heroism in combat. First, we report the results of an archival study on US-American soldiers who fought in World War II. We compare proxies for reproductive success between a control sample of 449 regular veterans and 123 surviving Medal of Honor recipients of WWII. Results suggest that the heroes sired more (...) offspring than the regular veterans. Supporting a causal link between war heroism and mating success, we then report the results of two experimental studies. We find evidence that female participants specifically regard men more sexually attractive if they are war heroes. This effect is absent for male participants judging female war heroes, suggesting that bravery in war is a gender specific signal. Finally, we discuss possible implications of our results. (shrink)

Feeling good: four ways -- Finding that feeling -- The place of pleasure -- Knowing what's what -- Making things happen -- Being good -- Love and friendship -- Putting it together.

We review the literature on various approaches to modeling animal intergroup conflict behavior in theoretical biology, highlight the intricacies emerging in the process of adding due biological realism to such models, and point out recent empirical findings that can inspire future theorizing.

Thomas Hill, a leading figure in the recent development of Kantian moral philosophy, presents a set of essays exploring the implications of basic Kantian ideas for practical issues. The first part of the book provides background in central themes in Kant's ethics; the second part discusses questions regarding human welfare; the third focuses on moral worth-the nature and grounds of moral assessment of persons as deserving esteem or blame. Hill shows moral, political, and social philosophers just how valuable moral (...) theory can be in addressing practical matters. (shrink)

Respect, Pluralism, and Justice is a series of essays which sketches a broadly Kantian framework for moral deliberation, and then uses it to address important social and political issues. Hill shows how Kantian theory can be developed to deal with questions about cultural diversity, punishment, political violence, responsibility for the consequences of wrongdoing, and state coercion in a pluralistic society.

The word “emotion” has named a psychological category and a subject for systematic enquiry only since the 19th century. Before then, relevant mental states were categorised variously as “appetites,” “passions,” “affections,” or “sentiments.” The word “emotion” has existed in English since the 17th century, originating as a translation of the French émotion, meaning a physical disturbance. It came into much wider use in 18th-century English, often to refer to mental experiences, becoming a fully fledged theoretical term in the following century, (...) especially through the influence of two Scottish philosopher-physicians, Thomas Brown and Charles Bell. This article relates this intellectual and semantic history to contemporary debates about the usefulness and meaning of “emotion” as a scientific term. (shrink)

Nietzsche is often regarded as a paradigmatically anti-theoretical philosopher. Bernard Williams has said that Nietzsche is so far from being a theorist that his text “is booby-trapped not only against recovering theory from it, but, in many cases, against any systematic exegesis that assimilates it to theory.” Many would apply this view especially to Nietzsche’s moral philosophy. They would say that even when he is making positive normative claims, as against just criticizing existing morality, his claims have neither the content (...) nor the organization characteristic of moral theory. (shrink)

For early modern metaphysician Anne Conway, the world comprises creatures. In some sense, Conway is a monist about creatures: all creatures are one. Yet, as Jessica Gordon-Roth has astutely pointed out, that monism can be understood in very different ways. One might read Conway as an ‘existence pluralist’: creatures are all composed of the same type of substance, but many substances exist. Alternatively, one might read Conway as an ‘existence monist’: there is only one created substance. Gordon-Roth has done the (...) scholarship a great favor by illuminating these issues in Conway. However, this article takes issue with Gordon-Roth's further view that Conway ‘oscillates’ between the extremes of existence pluralism and monism. In its place, I argue we should read Conway as a priority monist: the whole of creation is ontologically prior to its parts. (shrink)

The ten original studies included in this Research Topic investigate selected assumptions and predictions of parochial altruism theory in detail. We, the editors, are convinced that their highly instructive findings will help researchers interested in parochial altruism, but also in intergroup psychology more generally, to gain a much more fine-grained understanding of the interplay of altruistic and spiteful motives in human decision making in the context of intergroup relations. The broad range of disciplines represented by the authors contributing to this (...) Research Topic and the variety of methods used in their studies are representative for the current interdisciplinary interest in parochial altruism. The most important insight that, in our view, can be derived from the works collected here is that human decision making in intergroup contexts is more complex than suggested by current theory. Thus, we hope that future theorizing on parochial altruism will be stimulated by the evidence gathered in this Research Topic. In this editorial, we briefly highlight central findings reported here, which, to us, appear most informative for prospective enhancements of parochial altruism theory. (shrink)

The influence of many factors on ecological success in common pool resource management is still unclear. This may be due to methodological issues. These include causal complexity, a lack of large-N-studies and nonlinear relationships between factors. We address all three issues with a new methodological approach, artificial neural networks, which is discussed in detail. It allows us to develop a model with comparably high predictive power. In addition, two success factors are analyzed: legal security and institutional fairness. Both factors show (...) a positive impact on success in irrigation and fisheries supporting the view that there are sector-independent success factors. (shrink)

The literature on common pool resource (CPR) governance lists numerous factors that influence whether a given CPR system achieves ecological long-term sustainability. Up to now there is no comprehensive model to integrate these factors or to explain success within or across cases and sectors. Difficulties include the absence of large-N-studies (Poteete 2008), the incomparability of single case studies, and the interdependence of factors (Agrawal and Chhatre 2006). We propose (1) a synthesis of 24 success factors based on the current SES (...) framework and a literature review; (2) the application of neural networks on a database of CPR management case studies in an attempt to test the viability of this synthesis. This method allows us to obtain an implicit quantitative and rather precise model of the interdependencies in CPR systems. Given such a model, every success factor in each case can be manipulated separately, yielding different predictions for success. This could become be a fast and inexpensive way to analyze, predict and optimize performance for communities world-wide facing CPR challenges. Existing theoretical frameworks could be improved as well. (shrink)

In this chapter, we present supporting arguments for the claim that Order Ethics is a school of thought within ethics which is especially open to empirical evidence. With its focus on order frameworks, i.e., incentive structures, Order Ethical advice automatically raises questions on implementability, efficacy, and efficiency of such recommended institutions, all of which are empirical questions to a good extent. We illustrate our arguments by presenting a small selection of experiments from economics that we consider highly informative for Order (...) Ethics. These experiments vary in their details but share one common theme: individual decision-making and its aggregate results are tested against the background of incentive structures. In particular, these studies provide first insights on how unregulated markets influence moral behavior over time, how trial-and-error experiences convince subjects to migrate to more efficient institutions, and how default rules can influence fundamental choices of people. We argue that Order Ethics, for which implementability of any moral claim is an essential requirement, can largely benefit from the use of such experimental methods. Finally, we suggest the provision of self-commitment devices as one example of smart policy design that avoids paternalistic intrusions into individual liberty. (shrink)

Phenomena like meat sharing in hunter-gatherers, self-sacrifice in intergroup conflicts, and voluntary contribution to public goods provision in laboratory experiments have led to the development of numerous theories on the evolution of altruistic in-group beneficial behavior in humans. Many of these theories abstract away from the effects of kinship on the incentives for public goods provision, though. Here, it is investigated analytically how genetic relatedness changes the incentive structure of that paradigmatic game which is conventionally used to model and experimentally (...) investigate collective action problems: the linear public goods game. Using recent anthropological data sets on relatedness in 61 contemporary hunter-gatherer and horticulturalist societies the relevant parameters of this model are then estimated. It turns out that the kinship patterns observed in these societies substantially reduce the negative effect of increasing group size on incentives for public goods provision. It is suggested, therefore, that renewed attention should be given to inclusive fitness theory in the context of public goods provision also in sizable groups, because its explanatory power with respect to this central problem in the evolution of human cooperativeness and altruism might have been substantially underrated. (shrink)

Phenomena like meat sharing in hunter-gatherers, altruistic self-sacrifice in intergroup conflicts, and contribution to the production of public goods in laboratory experiments have led to the development of numerous theories trying to explain human prosocial preferences and behavior. Many of these focus on direct and indirect reciprocity, assortment, or (cultural) group selection. Here, I investigate analytically how genetic relatedness changes the incentive structure of that paradigmatic game which is conventionally used to model and experimentally investigate collective action problems: the public (...) goods game. Using data on contemporary hunter-gatherer societies I then estimate a threshold value determining when biological altruism turns into maximizing inclusive fitness in this game. I find that, on average, contributing no less than about 40% of individual fitness to public goods production still is an optimal strategy from an inclusive fitness perspective under plausible socio-ecological conditions. (shrink)

This chapter discusses future directions which the current developments within philosophy might take. It does so on the background of historical parallels to the controversy around experimental philosophy. Historical debates in psychology and economics contain astonishing similarities to today’s discussions in philosophy. After a brief historical overview, four central criticisms which experimental philosophy is subject to are systematically reviewed. It is shown that three of these are not specifically philosophical. Rather, they neccessarily accompany and drive every introduction of experimental methods (...) to a discipline. Only the question if experimental methods can actually capture the objects of philosophical research remains as a – weak – candidate for a specifically philosophical problem. This question is discussed separately. Finally, a constructively critical pluralism of methods is advocated and more serenity demanded: Introducing experimental methods to philosophy is an experiment itself. We will simply have to wait and see if it succeeds. (shrink)

Serena Olsaretti brings together new essays by leading moral and political philosophers on the nature of desert and justice, their relations with each other and with other values.

The Prisoner’s Dilemma (PD) is widely used to model social interaction between unrelated individuals in the study of the evolution of cooperative behaviour in humans and other species. Many effective mechanisms and promotive scenarios have been studied which allow for small founding groups of cooperative individuals to prevail even when all social interaction is characterised as a PD. Here, a brief critical discussion of the role of the PD as the most prominent tool in cooperation research is presented, followed by (...) two new objections to such an exclusive focus on PD-based models of social interaction. It is highlighted that only 2 of the 726 combinatorially possible strategically unique ordinal 2x2 games have the detrimental characteristics of a PD and that the frequency of PD-type games in a space of games with random payoffs does not exceed about 3.5%. Although these purely mathematical considerations do not compellingly imply that the relevance of PDs is overestimated, it is proposed that, in the absence of convergent empirical information about the ancestral human social niche, this finding can be interpreted in favour of a so far rather neglected answer to the question of how the founding groups of human cooperation themselves came to cooperate: Behavioural and/or psychological mechanisms which evolved for other, possibly more frequent, social interaction situations might have been applied to PD-type dilemmas only later. Human cooperative behaviour might thus partly have begun as a cooptation. (shrink)