Learning to Reach Agreement in a Continuous Ultimatum Game

It is well-known that acting in an individually rational manner, according to the principles of classical game theory, may lead to sub-optimal solutions in a class of problems named social dilemmas. In contrast, humans generally do not have much difficulty with social dilemmas, as they are able to balance personal benefit and group benefit. As agents in multi-agent systems are regularly confronted with social dilemmas, for instance in tasks such as resource allocation, these agents may benefit from the inclusion of mechanisms thought to facilitate human fairness. Although many of such mechanisms have already been implemented in a multi-agent systems context, their application is usually limited to rather abstract social dilemmas with a discrete set of available strategies (usually two). Given that many real-world examples of social dilemmas are actually continuous in nature, we extend this previous work to more general dilemmas, in which agents operate in a continuous strategy space. The social dilemma under study here is the well-known Ultimatum Game, in which an optimal solution is achieved if agents agree on a common strategy. We investigate whether a scale-free interaction network facilitates agents to reach agreement, especially in the presence of fixed-strategy agents that represent a desired (e.g. human) outcome. Moreover, we study the influence of rewiring in the interaction network. The agents are equipped with continuous-action learning automata and play a large number of random pairwise games in order to establish a common strategy. From our experiments, we may conclude that results obtained in discrete-strategy games can be generalized to continuous-strategy games to a certain extent: a scale-free interaction network structure allows agents to achieve agreement on a common strategy, and rewiring in the interaction network greatly enhances the agents ability to reach agreement. However, it also becomes clear that some alternative mechanisms, such as reputation and volunteering, have many subtleties involved and do not have convincing beneficial effects in the continuous case

Trust among Internet Traders: A Behavioral Economics Approach

Standard economic theory does not capture trust among anonymous Internet traders. But when traders are allowed to have social preferences, uncertainty about a seller's morals opens the door for trust, reward, exploitation and reputation building. We report experiments suggesting that sellers' intrinsic motivations to be trustworthy are not sufficient to sustain trade when not complemented by a feedback system. We demonstrate that it is the interaction of social preferences and cleverly designed reputation mechanisms that solves to a large extent the trust problem on Internet market platforms. However, economic theory and social preference models tend to underestimate the difficulties of promoting trust in anonymous online trading communities.

Emergence of social networks via direct and indirect reciprocity

Many models of social network formation implicitly assume that network properties are static in steady-state. In contrast, actual social networks are highly dynamic: allegiances and collaborations expire and may or may not be renewed at a later date. Moreover, empirical studies show that human social networks are dynamic at the individual level but static at the global level: individuals' degree rankings change considerably over time, whereas network-level metrics such as network diameter and clustering coefficient are relatively stable. There have been some attempts to explain these properties of empirical social networks using agent-based models in which agents play social dilemma games with their immediate neighbours, but can also manipulate their network connections to strategic advantage. However, such models cannot straightforwardly account for reciprocal behaviour based on reputation scores ("indirect reciprocity"), which is known to play an important role in many economic interactions. In order to account for indirect reciprocity, we model the network in a bottom-up fashion: the network emerges from the low-level interactions between agents. By so doing we are able to simultaneously account for the effect of both direct reciprocity (e.g. "tit-for-tat") as well as indirect reciprocity (helping strangers in order to increase one's reputation). This leads to a strategic equilibrium in the frequencies with which strategies are adopted in the population as a whole, but intermittent cycling over different strategies at the level of individual agents, which in turn gives rise to social networks which are dynamic at the individual level but stable at the network level

The efficiency of the non-profit enterprise: constitutional ideology, conformist preferences and reputation

According to one thesis the non profit enterprise (in short NPE) is able to attract ideological entrepreneurs and workers (Rose-Ackerman 1996). In fact I prove that without the ideological element, a simple game between the entrepreneur, worker and beneficiary is condemned to an opportunistic equilibrium, beneficial to the internal members of the organization but detrimental to the beneficiary. Thus the NPE does not better than its for profit counterpart. In my model ideologues, both entrepreneurs and workers, share a principle of justice seen as the constitutional ideology of the NPE, agreed upon in an hypothetical ex ante bargaining game. The constitutional principle provides an independent source of motivation (a source of utility) of the players, in so far as they believe in the reciprocity of conformity to the ideology by all the participants. I call this conformity-based utility “ideological”, and I see it as the representation of a preference for expected conformity to the given constitutional principle. The philosophical underpinnings of this reform of the players' utility functions in worked out by distinguishing two concepts of preferences of the Self: consequentialist preferences and conformist preferences. The latter are preferences for those actions that are part of states of affairs described in terms of interdependent actions conforming to an abstract norm or principle, which become effective once the preferences' holder does expect that the other players do they part in that state of affairs and they do expect that himself do his part in the same state of affairs. What result is that a player's ideological utility depends on the expectation of deontological modes of behaviour followed by all the participants, himself included. On this basis it is possible to overcome personal incentives to embrace opportunistic behaviour, so that the proper Non-profit Enterprise emerges. It is proved that in the “social enterprise game” amongst the member of the organisation there exists an organisational equilibrium minimising transaction costs to the beneficiaries. At last, this equilibrium rests on the emergence of an expectations system of reciprocal conformity to the constitutional ideology. As the existence - not even the selection – of the internal organizational equilibrium rests heavily on the existence of the appropriate system of reciprocal expectation, the problem of how we can justify the emergence of the appropriate system of beliefs must be underlined. Here is where the explicit moral codes of the NPE enters the scene. I see the code of ethics as the building block for deriving a reputation equilibrium between the NPE as a whole and its external stakeholders within a repeated game, whose stage-game is the typical game of trust played under incomplete knowledge and unforeseen contingencies. At last the conformist-motivation model and the reputation model under unforeseen contingencies are shown to play together in a mutually supporting explanation of the efficiency of the NPE.

Social Preference, Incomplete Information, and the Evolution of Ultimatum Game in the Small World Networks: An Agent-Based Approach

Certain social preference models have been proposed to explain fairness behavior in experimental games. Existing bodies of research on evolutionary games, however, explain the evolution of fairness merely through the self-interest agents. This paper attempts to analyze the ultimatum game's evolution on complex networks when a number of agents display social preference. Agents' social preference is modeled in three forms: fairness consideration or maintaining a minimum acceptable money level, inequality aversion, and social welfare preference. Different from other spatial ultimatum game models, the model in this study assumes that agents have incomplete information on other agents' strategies, so the agents need to learn and develop their own strategies in this unknown environment. Genetic Algorithm Learning Classifier System algorithm is employed to address the agents' learning issue. Simulation results reveal that raising the minimum acceptable level or including fairness consideration in a game does not always promote fairness level in ultimatum games in a complex network. If the minimum acceptable money level is high and not all agents possess a social preference, the fairness level attained may be considerably lower. However, the inequality aversion social preference has negligible effect on the results of evolutionary ultimatum games in a complex network. Social welfare preference promotes the fairness level in the ultimatum game. This paper demonstrates that agents' social preference is an important factor in the spatial ultimatum game, and different social preferences create different effects on fairness emergence in the spatial ultimatum game.Spatial Ultimatum Game, Complex Network, Social Preference, Agent Based Modeling

Strengthening the accountability of independent regulatory agencies: From performance back to democracy

The autonomy of independent regulatory agencies (IRAs) raises concerns about how to keep them accountable. Remarkably, the process of Europeanisation has led to the emergence of a multilevel regulatory system linking IRAs to national and supranational actors but, on the other side, this process has influenced the capacity to make IRAs accountable. The literature about the accountability deficit of IRAs has tried to address this question, but the interplay between delegation, \u2018multi-levelisation\u2019 and accountability has not been thoroughly investigated yet. Notably, theoretical analysis of IRAs\u2019 accountability in multilevel regulatory environments is still scarce. This article is aimed at contributing to the debate by pointing out that any theoretical discussion about the accountability of IRAs should be framed in normative terms and, precisely, should reconsider a crucial dimension neglected so far, that is, the goals accountability is expected to achieve. The article, in fact, argues that in multilevel regulatory environments the impact of devices adopted to improve the accountability of IRAs is generally weakened by the presence of a \u2018neutral\u2019 idea of accountability, which dilutes its power. The only way to strengthen the effect of accountability is to bring politics and democratic values back into the regulatory process

The role of social cognition in decision making

Successful decision making in a social setting depends on our ability to understand the intentions, emotions and beliefs of others. The mirror system allows us to understand other people's motor actions and action intentions. ‘Empathy’ allows us to understand and share emotions and sensations with others. ‘Theory of mind’ allows us to understand more abstract concepts such as beliefs or wishes in others. In all these cases, evidence has accumulated that we use the specific neural networks engaged in processing mental states in ourselves to understand the same mental states in others. However, the magnitude of the brain activity in these shared networks is modulated by contextual appraisal of the situation or the other person. An important feature of decision making in a social setting concerns the interaction of reason and emotion. We consider four domains where such interactions occur: our sense of fairness, altruistic punishment, trust and framing effects. In these cases, social motivations and emotions compete with each other, while higher-level control processes modulate the interactions of these low-level biases

Network-based ranking in social systems: three challenges

Ranking algorithms are pervasive in our increasingly digitized societies, with important real-world applications including recommender systems, search engines, and influencer marketing practices. From a network science perspective, network-based ranking algorithms solve fundamental problems related to the identification of vital nodes for the stability and dynamics of a complex system. Despite the ubiquitous and successful applications of these algorithms, we argue that our understanding of their performance and their applications to real-world problems face three fundamental challenges: (i) Rankings might be biased by various factors; (2) their effectiveness might be limited to specific problems; and (3) agents' decisions driven by rankings might result in potentially vicious feedback mechanisms and unhealthy systemic consequences. Methods rooted in network science and agent-based modeling can help us to understand and overcome these challenges.Comment: Perspective article. 9 pages, 3 figure

The Growth of Organizational Variety in Market Economies: The Case of Social Enterprises

Institutional and organizational variety is increasingly characterising advanced economic systems. While traditional economic theories have focussed almost exclusively on profit-maximizing (i.e. for-profit) enterprises and on publicly-owned organizations, the increasing relevance of non-profit organizations, and especially of social enterprises, requires scientists to reflect on a new comprehensive economic approach for explaining this organizational variety. The paper examines the main limitations of the orthodox and institutional theories and comes to assert the need for creating and testing a new theoretical framework, which considers the way in which diverse enterprises pursue their goals, the diverse motivations driving actors and organizations, and the different learning patterns and routines within organizations. The new framework of analysis proposed in the paper draws upon recent developments in the theories of the firm, institutional evolution, and motivational complexity to explain the presence of diverse types of organizations on a continuum ranging from purely for-profit and commercial forms to socially-oriented entrepreneurial ones. (La varietà istituzionale ed organizzativa sta sempre più caratterizzando le economie avanzate. Mentre le teorie economiche tradizionali hanno tuttavia focalizzato l’attenzione esclusivamente sulle imprese che massimizzano il profitto (tipicamente le for-profit) e sulle organizzazioni pubbliche, la crescente importanza, in questi ultimi anni, delle organizzazioni nonprofit e specialmente delle imprese sociali sta richiedendo agli studiosi di ripensare un approccio economico capace di spiegare questa varietà organizzativa. Il presente articolo spiega i principali limiti della teoria ortodossa e delle teoria neo-istitizionalista e giunge ad affermare la necessità di creare e testare una nuova teoria economica che consideri le diversità negli obiettivi delle organizzazioni, le differenze nelle motivazioni degli attori economici e delle organizzazioni stesse, le differenti modalità di apprendimento e di generazione di routine all’interno delle organizzazioni. Il nuovo contesto di analisi proposto attinge ad alcuni recenti sviluppi delle analisi economiche dell’impresa ed in particolare all’evoluzione delle istituzioni e alla complessità motivazionale, giungendo a delineare la presenza di diverse tipologie organizzative lungo un continuum che va dalle organizzazioni interessate esclusivamente alla massimizzazione del profitto (for-profit) alle organizzazione orientate al benessere sociale.)Social enterprises, organizational pluralism, neo-institutional economics, behavioral economics, organizational continuum

The Constitution of the Nonprofit Enterprise: Ideals, Conformism and Reciprocity

We provide an account of the non profit enterprise based on the motivations of the agents involved. Our main idea is that these are ex -post motivated by both self-interest and a conditional willingness to conform to their ex ante accepted constitutional ideology, which are weighed up in a comprehensive utility function. Ideology is shaped as the result of a hypothetical ‘social' contract between the relevant figures participating in the venture, in particular an entrepreneur, a worker, and a consumer who acts as a dummy beneficiary in the ex-post stage. It can thus be defined as a normative principle of fairness that boils down to a distributive social welfare function defined over the outcomes of a game, which permits to order them according to their conformity to the constitutional ideology. For conformist preferences depend upon expectations of reciprocal conformity to a normative principle, defined on social states described in as much they conform to an ideal, then the agents' model of choice asks for the adoption of the psychological games approach, where payoff functions range over not only the players' strategies but also their beliefs. If the conformist prompt to action is sufficiently strong then the outcome in which both the active agents perform an action improving the quality of the good with respect to the free market standard, thus maximising the surplus of the consumers, results in a psychological Nash equilibrium of the game. We associate this outcome, and the corresponding norm of behaviour, with the constitution of the non profit enterprise. We also show that the structure of the interaction is a coordination game, thus calling for the necessity of devices such as codes of ethics to solve the coordination problem. Keywords: Nonprofit, non-self-interested motivations, conformism, reciprocity, ideology.