Papers by Christian Hilbe
Reconciling Different Views on Responsible Leadership: A Rationality-Based Approach
Journal of Business Ethics, 2013
ABSTRACT Business leaders are increasingly responsible for the societal and environmental impacts... more ABSTRACT Business leaders are increasingly responsible for the societal and environmental impacts of their actions. Yet conceptual views on responsible leadership differ in their definitions and theoretical foundations. This study attempts to reconcile these diverse views and uncover the phenomenon from a business leader’s point of view. Based on rational egoism theory, this article proposes a formal mathematical model of responsible leadership that considers different types of incentives for stakeholder engagement. The analyses reveal that monetary and instrumental incentives are neither sufficient nor necessary for business leaders to consider societal and environmental stakeholder needs. Non-monetary and non-instrumental incentives, such as leaders’ values and authenticity, as well as their planning horizons, counterbalance pure monetary and instrumental orientations. The model in this article complements the growing body of research on responsible leadership by reconciling its various conceptual views and providing a foundation for future theory development and testing.
Partners or rivals? Strategies for the iterated prisoner's dilemma
Games and Economic Behavior, 2015
Within the class of memory-one strategies for the iterated Prisoner's Dilemma, we... more Within the class of memory-one strategies for the iterated Prisoner's Dilemma, we characterize partner strategies, competitive strategies and zero-determinant strategies. If a player uses a partner strategy, both players can fairly share the social optimum; but a co-player preferring an unfair solution will be penalized by obtaining a reduced payoff. A player using a competitive strategy never obtains less than the co-player. A player using a zero-determinant strategy unilaterally enforces a linear relation between the two players' payoffs. These properties hold for every strategy used by the co-player, whether memory-one or not.
Direct reciprocity and conditional cooperation are important mechanisms to prevent free riding in... more Direct reciprocity and conditional cooperation are important mechanisms to prevent free riding in social dilemmas. However, in large groups, these mechanisms may become ineffective because they require single individuals to have a substantial influence on their peers. However, the recent discovery of zero-determinant strategies in the iterated prisoner's dilemma suggests that we may have underestimated the degree of control that a single player can exert. Here, we develop a theory for zero-determinant strategies for iterated multiplayer social dilemmas, with any number of involved players. We distinguish several particularly interesting subclasses of strategies: fair strategies ensure that the own payoff matches the average payoff of the group; extortionate strategies allow a player to perform above average; and generous strategies let a player perform below average. We use this theory to describe strategies that sustain cooperation, including generalized variants of Tit-for-Tat and Win-Stay Lose-Shift. Moreover, we explore two models that show how individuals can further enhance their strategic options by coordinating their play with others. Our results highlight the importance of individual control and coordination to succeed in large groups. evolutionary game theory | alliances | public goods game | volunteer's dilemma | cooperation C ooperation among self-interested individuals is generally difficult to achieve (1-3), but typically the free rider problem is aggravated even further when groups become large (4-9). In small communities, cooperation can often be stabilized by forms of direct and indirect reciprocity (10-17). For large groups, however, it has been suggested that these mechanisms may turn out to be ineffective, as it becomes more difficult to keep track of the reputation of others and because the individual influence on others diminishes (4-8). To prevent the tragedy of the commons and to compensate for the lack of individual control, many successful communities have thus established central institutions that enforce mutual cooperation (18-22).
Nature communications, 2014
Extortion is the practice of obtaining advantages through explicit forces and threats. Recently, ... more Extortion is the practice of obtaining advantages through explicit forces and threats. Recently, it was demonstrated that even the repeated prisoner's dilemma, one of the key models to explain mutual cooperation, allows for implicit forms of extortion. According to the theory, extortioners demand and receive an excessive share of any surplus, which allows them to outperform any adapting co-player. To explore the performance of such strategies against humans, we have designed an economic experiment in which participants were matched either with an extortioner or with a generous co-player. Although extortioners succeeded against each of their human opponents, extortion resulted in lower payoffs than generosity. Human subjects showed a strong concern for fairness: they punished extortion by refusing to fully cooperate, thereby reducing their own, and even more so, the extortioner's gains. Thus, the prospects of extorting others in social relationships seem limited; in the long ...
Responsible Leadership–a Rational Perspective
Voluntary Leadership in Teams and the Leadership Paradox
Darwin and the Evolution of Human Cooperation
Principles of Evolution: From the Planck Epoch to Complex Multicellular Life, 2011
... Darwin, who was well versed in the writings of economists such as Adam Smith or Robert ... by... more ... Darwin, who was well versed in the writings of economists such as Adam Smith or Robert ... by hissocial qualities, which led him to give and receive aid from his fellow men ... to receive: this economic viewpoint anticipated the second major approach to the evolution of cooperation. ...
Scientific Reports, 2012
While empirical evidence highlights the importance of punishment for cooperation in collective ac... more While empirical evidence highlights the importance of punishment for cooperation in collective action, it remains disputed how responsible sanctions targeted predominantly at uncooperative subjects can evolve. Punishment is costly; in order to spread it typically requires local interactions, voluntary participation, or rewards. Moreover, theory and experiments indicate that some subjects abuse sanctioning opportunities by engaging in antisocial punishment (which harms cooperators), spiteful acts (harming everyone) or revenge (as a response to being punished). These arguments have led to the conclusion that punishment is maladaptive. Here, we use evolutionary game theory to show that this conclusion is premature: If interactions are non-anonymous, cooperation and punishment evolve even if initially rare, and sanctions are directed towards non-cooperators only. Thus, our willingness to punish free riders is ultimately a selfish decision rather than an altruistic act; punishment serves as a warning, showing that one is not willing to accept unfair treatments.
Modelling the dynamics of crime and punishment
Physics of Life Reviews, 2015
Scientific Reports, 2014
Mafia like behavior, where individuals cooperate under the threat of punishment, occurs not only ... more Mafia like behavior, where individuals cooperate under the threat of punishment, occurs not only in humans, but is also observed in several animal species. Observations suggest that avian hosts tend to accept a certain degree of parasitism in order to avoid retaliating punishment from the brood parasite. To understand under which conditions it will be beneficial for a host to cooperate, we model the interaction between hosts and parasites as an evolutionary game. In our model, the host's behavior is plastic, and thus, its response depends on the previous interactions with the parasite. We find that such learned behavior in turn is crucial for the evolution of retaliating parasites. The abundance of this kind of mafia behavior oscillates in time and does not settle to an equilibrium. Our results suggest that retaliation is a mechanism for the parasite to evade specialization and to induce acceptance by the host.
Proceedings of the Royal Society B: Biological Sciences, 2010
Cooperation in public good games is greatly promoted by positive and negative incentives. In this... more Cooperation in public good games is greatly promoted by positive and negative incentives. In this paper, we use evolutionary game dynamics to study the evolution of opportunism (the readiness to be swayed by incentives) and the evolution of trust (the propensity to cooperate in the absence of information on the co-players). If both positive and negative incentives are available, evolution leads to a population where defectors are punished and players cooperate, except when they can get away with defection. Rewarding behaviour does not become fixed, but can play an essential role in catalysing the emergence of cooperation, especially if the information level is low.
Proceedings of the National Academy of Sciences, 2014
Individuals usually punish free riders but refuse to sanction those who cooperate but do not puni... more Individuals usually punish free riders but refuse to sanction those who cooperate but do not punish. This missing second-order peer punishment is a fundamental problem for the stabilization of cooperation. To solve this problem, most societies today have implemented central authorities that punish free riders and tax evaders alike, such that second-order punishment is fully established. The emergence of such stable authorities from individual decisions, however, creates a new paradox: it seems absurd to expect individuals who do not engage in second-order punishment to strive for an authority that does. Herein, we provide a mathematical model and experimental results from a public goods game where subjects can choose between a community with and without second-order punishment in two different ways. When subjects can migrate continuously to either community, we identify a bias toward institutions that do not punish tax evaders. When subjects have to vote once for all rounds of the game and have to accept the decision of the majority, they prefer a society with second-order punishment. These findings uncover the existence of a democracy premium. The majority-voting rule allows subjects to commit themselves and to implement institutions that eventually lead to a higher welfare for all. evolution of cooperation | pool punishment | institution formation T he success of collective action and the maintenance of commonly shared infrastructure is often endangered by free riders, subjects who reap the benefits of public goods without contributing to them (1, 2). To mitigate the free riders' destructive potential, many communities install specialized authorities that monitor the subjects' behavior and sanction wrong-doers (3-7). Examples, such as modern courts and the police system, indicate that the maintenance of such institutions is costly. They also constitute a commonly shared infrastructure, which can be exploited just as the original public good that the institution was designed for to protect. Thus, a second-order dilemma arises.
Proceedings of the National Academy of Sciences, 2013
Iterated games are a fundamental component of economic and evolutionary game theory. They describ... more Iterated games are a fundamental component of economic and evolutionary game theory. They describe situations where two players interact repeatedly and have the ability to use conditional strategies that depend on the outcome of previous interactions, thus allowing for reciprocation. Recently, a new class of strategies has been proposed, so-called "zero-determinant" strategies. These strategies enforce a fixed linear relationship between one's own payoff and that of the other player. A subset of those strategies allows "extortioners" to ensure that any increase in one player's own payoff exceeds that of the other player by a fixed percentage. Here, we analyze the evolutionary performance of this new class of strategies. We show that in reasonably large populations, they can act as catalysts for the evolution of cooperation, similar to tit-fortat, but that they are not the stable outcome of natural selection. In very small populations, however, extortioners hold their ground. Extortion strategies do particularly well in coevolutionary arms races between two distinct populations. Significantly, they benefit the population that evolves at the slower rate, an example of the so-called "Red King" effect. This may affect the evolution of interactions between host species and their endosymbionts.
PLoS ONE, 2013
Direct reciprocity is a mechanism for the evolution of cooperation. For the iterated prisoner's d... more Direct reciprocity is a mechanism for the evolution of cooperation. For the iterated prisoner's dilemma, a new class of strategies has recently been described, the so-called zero-determinant strategies. Using such a strategy, a player can unilaterally enforce a linear relationship between his own payoff and the co-player's payoff. In particular the player may act in such a way that it becomes optimal for the co-player to cooperate unconditionally. In this way, a player can manipulate and extort his co-player, thereby ensuring that the own payoff never falls below the co-player's payoff. However, using a compliant strategy instead, a player can also ensure that his own payoff never exceeds the co-player's payoff. Here, we use adaptive dynamics to study when evolution leads to extortion and when it leads to compliance. We find a remarkable cyclic dynamics: in sufficiently large populations, extortioners play a transient role, helping the population to move from selfish strategies to compliance. Compliant strategies, however, can be subverted by altruists, which in turn give rise to selfish strategies. Whether cooperative strategies are favored in the long run critically depends on the size of the population; we show that cooperation is most abundant in large populations, in which case average payoffs approach the social optimum. Our results are not restricted to the case of the prisoners dilemma, but can be extended to other social dilemmas, such as the snowdrift game. Iterated social dilemmas in large populations do not lead to the evolution of strategies that aim to dominate their co-player. Instead, generosity succeeds.
PLoS ONE, 2013
In collective-risk dilemmas, a group needs to collaborate over time to avoid a catastrophic event... more In collective-risk dilemmas, a group needs to collaborate over time to avoid a catastrophic event. This gives rise to a coordination game with many equilibria, including equilibria where no one contributes, and thus no measures against the catastrophe are taken. In this game, the timing of contributions becomes a strategic variable that allows individuals to interact and influence one another. Herein, we use evolutionary game theory to study the impact of strategic timing on equilibrium selection. Depending on the risk of catastrophe, we identify three characteristic regimes. For low risks, defection is the only equilibrium, whereas high risks promote equilibria with sufficient contributions. Intermediate risks pose the biggest challenge for cooperation. In this risk regime, the option to interact over time is critical; if individuals can contribute over several rounds, then the group has a higher chance to succeed, and the expected welfare increases. This positive effect of timing is of particular importance in larger groups, where successful coordination becomes increasingly difficult. Citation: Hilbe C, Abou Chakra M, Altrock PM, Traulsen A (2013) The Evolution of Strategic Timing in Collective-Risk Dilemmas. PLoS ONE 8(6): e66490.
Journal of Theoretical Biology, 2014
We show how public knowledge about punishment institutions can affect their evolution. Subjects c... more We show how public knowledge about punishment institutions can affect their evolution. Subjects can establish a punishment institution before they play a public goods game. The evolutionary dynamics leads to a coexistence of pool punishers and opportunists. Pool punishment can evolve without second-order punishment and without loners.
Journal of theoretical biology, Jan 2, 2015
Repetition is one of the key mechanisms to maintain cooperation. In long-term relationships, in w... more Repetition is one of the key mechanisms to maintain cooperation. In long-term relationships, in which individuals can react to their peers' past actions, evolution can promote cooperative strategies that would not be stable in one-shot encounters. The iterated prisoner's dilemma illustrates the power of repetition. Many of the key strategies for this game, such as ALLD, ALLC, Tit-for-Tat, or generous Tit-for-Tat, share a common property: players using these strategies enforce a linear relationship between their own payoff and their co-player's payoff. Such strategies have been termed zero-determinant (ZD). Recently, it was shown that ZD strategies also exist for multiplayer social dilemmas, and here we explore their evolutionary performance. For small group sizes, ZD strategies play a similar role as for the repeated prisoner's dilemma: extortionate ZD strategies are critical for the emergence of cooperation, whereas generous ZD strategies are important to maintain c...
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Papers by Christian Hilbe