Terrorist defectors : are we ready? : hearing before the Committee on Governmental Affairs, United States Senate, One Hundred Second Congress, second session, February 4, 1992.

Shipping list no.: 93-0024-P.

Identity, difference, and the dilemmas of inter-Korean relations: Insights from northern defectors and the German precedent

Questions of identity have become increasingly central to the study of foreign policy and security, particularly in constructivist debates. But very few of the resulting insights have been applied to the Korean situation, where discussions about security and inter-Korean relations remain dominated by strategic and geopolitical issues. The main task of this article is to address this shortcoming by examining the experience of North Korean defectors in South Korea and the precedent of German unification. Both of these domains of inquiry reveal that identity differences between North and South persist far beyond the ideological and political structures that created them in the first place. Born out of death, fear, and longing for revenge, these identity patterns lie at the heart of Korea's security dilemmas. Unless taken seriously by scholars and decision makers, the respective tensions between identity and difference will continue to cause major political problems. (Key words: Inter-Korean relations, North Korean defectors, German unification)

Nuclear Weapons as Symbols. The Role of Norms in Nuclear Policy Making

Throughout history, nuclear weapons have been considered to be the ultimate weapons. This understanding largely detached them from the portfolio of conventional military means and assigned them a symbolic meaning that influenced the identity and norms creation of nations. In most countries today, the development of nuclear weapons is considered morally prohibitive, incompatible with a country’s identity and international outlook. In some states, however, these negative norms are overridden by a positive set of norms, causing nuclear weapons to become either symbols of invulnerability to perceived threats or the regalia of major power status. Main purpose of this paper is to explore on the conditions that cause most states to develop a moral aversion to nuclear weapons, yet effectively lead to their glorification in others. Many studies on the normative understanding of nuclear weapons consider the existence of a negative normative predisposition, often referred to as ‘nuclear taboo’, as a major factor in preventing their acquisition and use. Other studies acknowledge the existence of a nuclear taboo inhibiting the use of nuclear weapons, but point to the existence of the opposing effect of norms, frequently referred to as the ‘nuclear myth’, when it comes to the acquisition of nuclear weapons. This myth emerges when certain symbolic meanings are attached to nuclear weapons, such as a state’s identity, self-image, and its desired position in the international system. With 180 odd countries in the world abstaining from the acquisition of nuclear weapons and 8 countries in possession of them (with two further countries assumed to have pursued their acquisition), one might consider the dominance of the nuclear taboo over the nuclear myth to be the rule. The core question is thus why and how this relationship reversed in the case of defectors.

Strong reciprocity or strong ferocity? A population genetic view of the evolution of altruistic punishment.

Strong reciprocity, defined as a predisposition to help others and to punish those that are not helping, has been proposed as a potent force leading to the evolution of cooperation and altruism. However, the conditions under which strong reciprocity might be favored are not clear. Here we investigate the selective pressure on strong reciprocity by letting both limited dispersal (i.e., spatial structure) and recombination between helping and punishment jointly determine the evolutionary dynamics of strong reciprocity. Our analytical model suggests that when helping and punishment are perfectly linked traits (no recombination occurring between them), strong reciprocity can spread even when the initial frequency of strong reciprocators is close to 0 in the population (i.e., a rare mutant can invade). By contrast, our results indicate that when recombination can occur between helping and punishment (i.e., both traits coevolve) and is stronger than selection, punishment is likely to invade a population of defectors only when it gives a direct fitness benefit to the actor. Overall, our results delineate the conditions under which strong reciprocity is selected for in a spatially structured population and highlight that the forces behind its evolution involves kinship (be it genetic or cultural).

The evolution of punishment through reputation.

Punishment of non-cooperators has been observed to promote cooperation. Such punishment is an evolutionary puzzle because it is costly to the punisher while beneficial to others, for example, through increased social cohesion. Recent studies have concluded that punishing strategies usually pay less than some non-punishing strategies. These findings suggest that punishment could not have directly evolved to promote cooperation. However, while it is well established that reputation plays a key role in human cooperation, the simple threat from a reputation of being a punisher may not have been sufficiently explored yet in order to explain the evolution of costly punishment. Here, we first show analytically that punishment can lead to long-term benefits if it influences one's reputation and thereby makes the punisher more likely to receive help in future interactions. Then, in computer simulations, we incorporate up to 40 more complex strategies that use different kinds of reputations (e.g. from generous actions), or strategies that not only include punitive behaviours directed towards defectors but also towards cooperators for example. Our findings demonstrate that punishment can directly evolve through a simple reputation system. We conclude that reputation is crucial for the evolution of punishment by making a punisher more likely to receive help in future interactions, and that experiments investigating the beneficial effects of punishment in humans should include reputation as an explicit feature.

Exposure to superfluous information reduces cooperation and increases antisocial punishment in reputation-based interactions

Human cooperation is often based on reputation gained from previous interactions with third parties. Such reputation can be built on generous or punitive actions, and both, one's own reputation and the reputation of others have been shown to influence decision making in experimental games that control for confounding variables. Here we test how reputation-based cooperation and punishment react to disruption of the cognitive processing in different kinds of helping games with observers. Saying a few superfluous words before each interaction was used to possibly interfere with working memory. In a first set of experiments, where reputation could only be based on generosity, the disruption reduced the frequency of cooperation and lowered mean final payoffs. In a second set of experiments where reputation could only be based on punishment, the disruption increased the frequency of antisocial punishment (i.e. of punishing those who helped) and reduced the frequency of punishing defectors. Our findings suggest that working memory can easily be constraining in reputation-based interactions within experimental games, even if these games are based on a few simple rules with a visual display that provides all the information the subjects need to play the strategies predicted from current theory. Our findings also highlight a weakness of experimental games, namely that they can be very sensitive to environmental variation and that quantitative conclusions about antisocial punishment or other behavioral strategies can easily be misleading.

The evolution of anti-social rewarding and its countermeasures in public goods games.

Cooperation in joint enterprises can easily break down when self-interests are in conflict with collective benefits, causing a tragedy of the commons. In such social dilemmas, the possibility for contributors to invest in a common pool-rewards fund, which will be shared exclusively among contributors, can be powerful for averting the tragedy, as long as the second-order dilemma (i.e. withdrawing contribution to reward funds) can be overcome (e.g. with second-order sanctions). However, the present paper reveals the vulnerability of such pool-rewarding mechanisms to the presence of reward funds raised by defectors and shared among them (i.e. anti-social rewarding), as it causes a cooperation breakdown, even when second-order sanctions are possible. I demonstrate that escaping this social trap requires the additional condition that coalitions of defectors fare poorly compared with pro-socials, with either (i) better rewarding abilities for the latter or (ii) reward funds that are contingent upon the public good produced beforehand, allowing groups of contributors to invest more in reward funds than groups of defectors. These results suggest that the establishment of cooperation through a collective positive incentive mechanism is highly vulnerable to anti-social rewarding and requires additional countermeasures to act in combination with second-order sanctions.

Mutual trust and cooperation in the evolutionary hawks-doves game

Using a new dynamical network model of society in which pairwise interactions are weighted according to mutual satisfaction, we show that cooperation is the norm in the hawks-doves game when individuals are allowed to break ties with undesirable neighbors and to make new acquaintances in their extended neighborhood. Moreover, cooperation is robust with respect to rather strong strategy perturbations. We also discuss the empirical structure of the emerging networks, and the reasons that allow cooperators to thrive in the population. Given the metaphorical importance of this game for social interaction, this is an encouraging positive result as standard theory for large mixing populations prescribes that a certain fraction of defectors must always exist at equilibrium.

The co-evolution of social institutions, demography, and large-scale human cooperation.

Human cooperation is typically coordinated by institutions, which determine the outcome structure of the social interactions individuals engage in. Explaining the Neolithic transition from small- to large-scale societies involves understanding how these institutions co-evolve with demography. We study this using a demographically explicit model of institution formation in a patch-structured population. Each patch supports both social and asocial niches. Social individuals create an institution, at a cost to themselves, by negotiating how much of the costly public good provided by cooperators is invested into sanctioning defectors. The remainder of their public good is invested in technology that increases carrying capacity, such as irrigation systems. We show that social individuals can invade a population of asocials, and form institutions that support high levels of cooperation. We then demonstrate conditions where the co-evolution of cooperation, institutions, and demographic carrying capacity creates a transition from small- to large-scale social groups.

Effects of punishment in a mobile population playing the prisoner’s dilemma game

We deal with a system of prisoner’s dilemma players undergoing continuous motion in a two-dimensional plane. In contrast to previous work, we introduce altruistic punishment after the game. We find punishing only a few of the cooperator-defector interactions is enough to lead the system to a cooperative state in environments where otherwise defection would take over the population. This happens even with soft nonsocial punishment (where both cooperators and defectors punish other players, a behavior observed in many human populations). For high enough mobilities or temptations to defect, low rates of social punishment can no longer avoid the breakdown of cooperation

A study of disaffection in Upper Canada in 1812-5 /

Inscribed on verso of front cover: H.R. Morgan Esq. with compts of E.A. Cruikshank.

Complex Transition to Cooperative Behavior in a Structured Population Model

Cooperation plays an important role in the evolution of species and human societies. The understanding of the emergence and persistence of cooperation in those systems is a fascinating and fundamental question. Many mechanisms were extensively studied and proposed as supporting cooperation. The current work addresses the role of migration for the maintenance of cooperation in structured populations. This problem is investigated in an evolutionary perspective through the prisoner's dilemma game paradigm. It is found that migration and structure play an essential role in the evolution of the cooperative behavior. The possible outcomes of the model are extinction of the entire population, dominance of the cooperative strategy and coexistence between cooperators and defectors. The coexistence phase is obtained in the range of large migration rates. It is also verified the existence of a critical level of structuring beyond that cooperation is always likely. In resume, we conclude that the increase in the number of demes as well as in the migration rate favor the fixation of the cooperative behavior.

Reciprocal cooperation between unrelated rats depends on cost to donor and benefit to recipient

Background Although evolutionary models of cooperation build on the intuition that costs of the donor and benefits to the receiver are the most general fundamental parameters, it is largely unknown how they affect the decision of animals to cooperate with an unrelated social partner. Here we test experimentally whether costs to the donor and need of the receiver decide about the amount of help provided by unrelated rats in an iterated prisoner's dilemma game. Results Fourteen unrelated Norway rats were alternately presented to a cooperative or defective partner for whom they could provide food via a mechanical apparatus. Direct costs for this task and the need of the receiver were manipulated in two separate experiments. Rats provided more food to cooperative partners than to defectors (direct reciprocity). The propensity to discriminate between helpful and non-helpful social partners was contingent on costs: An experimentally increased resistance in one Newton steps to pull food for the social partner reduced the help provided to defectors more strongly than the help returned to cooperators. Furthermore, test rats provided more help to hungry receivers that were light or in poor condition, which might suggest empathy, whereas this relationship was inverse when experimental partners were satiated. Conclusions In a prisoner's dilemma situation rats seem to take effect of own costs and potential benefits to a receiver when deciding about helping a social partner, which confirms the predictions of reciprocal cooperation. Thus, factors that had been believed to be largely confined to human social behaviour apparently influence the behaviour of other social animals as well, despite widespread scepticism. Therefore our results shed new light on the biological basis of reciprocity.

Generosity is a sign of trustworthiness—the punishment of selfishness is not

Peer-punishment is an important determinant of cooperation in human groups. It has been suggested that, at the proximate level of analysis, punitive preferences can explain why humans incur costs to punish their deviant peers. How punitive preferences could have evolved in humans is still not entirely understood. A possible explanation at the ultimate level of analysis comes from signaling theory. It has been argued that the punishment of defectors can be a type-separating signal of the punisher's cooperative intent. As a result, punishers are selected more often as interaction partners in social exchange and are partly compensated for the costs they incur when punishing defectors. A similar argument has been made with regard to acts of generosity. In a laboratory experiment, we investigate whether the punishment of a selfish division of money in a dictator game is a sign of trustworthiness and whether punishers are more trustworthy interaction partners in a trust game than non-punishers. We distinguish between second-party and third-party punishment and compare punitive acts with acts of generosity as signs of trustworthiness. We find that punishers are not more trustworthy than non-punishers and that punishers are not trusted more than non-punishers, both in the second-party and in the third-party punishment condition. To the contrary, second-party punishers are trusted less than their non-punishing counterparts. However, participants who choose a generous division of money are more trustworthy and are trusted more than participants who choose a selfish division or participants about whom no information is available. Our results suggest that, unlike for punitive acts, the signaling benefits of generosity are to be gained in social exchange.

Population dynamics, demographic stochasticity, and the evolution of cooperation

A basic evolutionary problem posed by the Iterated Prisoner’s Dilemma game is to understand when the paradigmatic cooperative strategy Tit-for-Tat can invade a population of pure defectors. Deterministically, this is impossible. We consider the role of demographic stochasticity by embedding the Iterated Prisoner’s Dilemma into a population dynamic framework. Tit-for-Tat can invade a population of defectors when their dynamics exhibit short episodes of high population densities with subsequent crashes and long low density periods with strong genetic drift. Such dynamics tend to have reddened power spectra and temporal distributions of population size that are asymmetric and skewed toward low densities. The results indicate that ecological dynamics are important for evolutionary shifts between adaptive peaks.