Bernd Lahno

The extent to which trust prevails can be measured by the subjective probability with which an agent expects another one to act in desired ways. An agent´s trust in other agents forms in repeated social interactions which typically have the structure of an elementary game of trust. The process of trust formation in such interactions may be described by a reputation function. It is argued that in view of real world processes of trust formation any adequate reputation function must satisfy certain conditions. A simple model conforming to these conditions is presented. Analysing this example it is shown that there is a co-operative Nash equilibrium in a trust supergame which is in line with the basic conditions of trust formation. However, it is also proved that no process of trust formation can be reasonably similar to real world mechanisms and at the same time lead to subgame perfect equilibria in a trust supergame.

Within the rational choice approach trust is usually analysed as a problem of choice under uncertainty. In a standard social situation in which trust plays a role a trustor A has to choose between trusting or mistrusting a trustee B. If he chooses to trust, B can either honour the trust given which will be of some advantage to both or exploit it no matter what the consequences for A are. A can in general protect himself against being exploited by choosing not to trust. But then he forgoes the possible advantages of trustful co-operation. A´s problem typically is that he is not sufficiently informed about B´s incentives or motivation. He may, for instance, not know whether B possesses some favourable character traits or not. The paper uses the well known game of trust with imperfect information to illustrate the core of the problem. From a rational choice point of view the possibility of a trustful decision is determined by the beliefs of A concerning B´s preferences. Thus the crucial parameter in the model is a probability measure p that measures A´s subjective expectations that a rational B will co-operate. According to the standard rational choice account trust is either a consequence or simply the expression of the expectations of a trustee represented by p. I refer to this account of trust as the theory of trust as rational expectancy. I shall criticise this solely cognitive view of trust for neglecting some central aspects of trusting relationships. My argument draws on the distinction between trust and reliance. It will be based on some simple observations, in particular: 1. The perception of the choice problem by the trustor as well as his perception of the trustee and the trustee´s characteristics may depend on wether or not the trustor is in fact trusting or mistrusting. 2. The trustor´s evaluation of the possible outcomes may depend on wether or not the trustor is in fact trusting or mistrusting. 3. The motivation of the trustee will often depend on whether he is trusted or not. If my argument is sound, then - to some considerable extend - it is impossible to analyse trust problems solely in terms of options, preferences and believes. There simply are no preferences and believes of the interacting individuals which are prior to and independent of trust. Trust then must be understood as a cause or basis of a trustor´s expectations, and not as their consequence. I shall finish my considerations by pointing to some general implications for an account of trust as social capital.

While Rational Choice Theory (RC) may be understood as a theory of choice, which does not necessarily reflect actual deliberative processes, rule-following behavior is definitely based on a certain form of delibera- tion. This article aims at clarifying the relationship between the two. Being guided by instrumental rules, i.e., rules reducible to the maximiza- tion principle, is perfectly consistent with the fundamental behavioral assumptions of RC. But human individuals use other forms of rules in decision making, especially tie-breaking rules and coordination rules. It is argued that within RC no satisfying account of such rule-following behav- ior can be given. In particular it is impossible to determine suitable pref- erence orderings such that coordinating may be understood as maximizing relative to these orderings. Still, once there is coordination, following a coordination rule may be perfectly consistent with the basic assumptions of RC. So there might be a more complex theory of action that incorpo- rates RC as well as a satisfying theory of rule-guided behavior.

Unlike the supergame model assumes agents in exchange situations will normally not be perfectly informed on past behaviour of their partners. Also, they will be able to choose their partners to a certain extend. A formal model is presented that attempts to take account of these facts. It is supposed that for any actor the probability of finding a partner for a lucrative exchange depends on his past behaviour. A model of reputation formation is presented as a formal description of this interdependency. Based on this model it is shown that under certain conditions only co-operative conduct will pay in the long run. Thus it is confirmed that - given the mechanism of trust - rational agents may act trustworthy.

The majority rule has caught much attention in recent debate about the aggregation of judgments. But its role in finding the truth is limited. A majority of expert judgments is not necessarily authoritative, even if all experts are equally competent, if they make their judgments independently of each other, and if all the judgments are based on the same source of (good) evidence. In this paper I demonstrate this limitation by presenting a simple counterexample and a related general result. I pave the way for this argument by introducing a Bayesian model of evidence and expert judgment in order to give a precise account of the basic problem.

Für moderne Handlungskontexte erweist sich der klassische Verantwortungsbegriff als inadäquat. Ein alternatives Konzept der Verantwortung, das auf der Humeschen Theorie der künstlichen Tugenden basiert, wird entwickelt und an einem einfachen Koordinationsspiel illustriert. Verantwortung wird dabei als das Resultat eines sozialen Zuschreibungsprozesses bestimmt. Menschen, denen Verantwortung zugeschrieben wird, erfüllen eine Funktion als Bezugspunkt sozialer Koordination. Es wird argumentiert, dass eine solche Konzeption gegenüber der klassischen ein feineres und angemesseneres Verständnis des Verhältnisses von kausaler Urheberschaft und Verantwortung vermittelt. Einige Schlussfolgerungen mit Blick auf die Eigenschaften, die Personen in verantwortlichen Positionen haben sollten, werden gezogen. Gefordert sind: Autonomie, Integrität und Kompetenz.

Kommunikation kann als eine besondere Form der strategischen Interaktion verstanden werden. Die Spieltheorie stellt ein formales Instrumentarium zur Analyse strategischer Probleme zur Verfügung. Einige Grundkonzepte der Spieltheorie werden vorgestellt, und ihre Anwendung auf Probleme der Kommunikation an einfachen Modellen vom Typ des Signalspiels illustriert. Es wird argumentiert, dass Kommunikation durch ein typisches Dilemma individueller Rationalität gefährdet sein kann. Obwohl eine korrekte Anwendung von Regeln, die die Verwendung eines verfügbaren Zeichens festlegen, für alle Akteure vorteilhaft wäre, gelingt es rationalen Akteuren unter bestimmten Bedingungen nicht, die Regeln zu befolgen und entsprechende Konventionen zu etablieren.

With increasing complexity of the networks of social interaction new and more abstract forms of trust are in need. A conceptual analysis of different forms of trust, namely interpersonal trust, trust in groups and institutional trust is given. It is argued that institutional trust cannot totally replace interpersonal trust. Institutional trust rather builds on more personal forms of trust in that it is primarily formed in personal encounters with salient representatives of the institution and presupposes trust in others trusting in the institution. Any form of trust is grounded in some normative foundation. A trusting person can make herself vulnerable to the action of other individuals because she perceives those others as acting from shared aims or values. Thus, some sort of virtue is a prerequisite of any form of genuine trust. While institutional trust may in some respect be more easily acquired than interpersonal trust in general it may bear a fundamental problem: institutional trust may be extraordinary robust with regard to a wide range of behavioral experiences; thus, it may be enduringly maintained although in fact unjustified. In a concluding section the general analysis is illustrated by some reflections on the problem of trust in government.

A particular problem of traditional Rational Choice Theory is that it cannot explain equilibrium selection in simple coordination games. In this paper we analyze and discuss the solution concept for common coordination problems as incorporated in the theory of Team Reasoning (TR). Special consideration is given to TR’s concept of opportunistic choice and to the resulting restrictions in using private information. We report results from a laboratory experiment in which teams were given a chance to coordinate on a particular pattern of behavior in a sequence of HiLo games. A modification of the stage game offered opportunities to improve on the team goal through changing this accustomed pattern of behavior. Our observations throw considerable doubt on the idea of opportunistic team reasoning as a guide to coordination. Contrary to what TR would predict, individuals tend to stick to accustomed behavioral patterns. Moreover, we find that individual decisions are at least partly determined by private information not accessible to all members of a team. Alternative theories of choice, in particular cognitive hierarchy theory may be more suitable to explain the observed pattern of behavior.