Titel: On Six Advances in Cooperation Theory
Autor: Robert Axelrod
Abstract: The symposium included in this issue of ANALYSE & KRITIK extends the basis of Cooperation Theory as set forth in Axelrod's 'Evolution of Cooperation' (1984). This essay begins with an overview of Cooperation Theory in terms of the questions it asks, its relationship to game theory and rationality, and the principal methodologies used, namely deduction and simulation. This essay then addresses the issues raised in the symposium, including the consequences of extending the original paradigm of the two person iterated Prisoner's Dilemma to take into account such factors as nonsimultaneous play, the ability to offer hostages for performance, social networks of interaction, information sharing that can support reputations, learning behavior, envy, misunderstanding, and an option to exit. The essay places the contributions of this symposium in the context of previous research on these and related issues.
Titel: Kooperative Strategien im Gefangenendilemma. Computersimulation eines N-Personen-Spiels
Autor: Andreas Diekmann / Klaus Manhart
Abstract: Simulation studies in the context of Robert Axelrod's research on iterative prisoner's dilemma games focus nearly exclusively on the two-player-version of the game. In contrast, this article reports results of a simulation with an iterated N-prisoners, dilemma where group size N varies between 2 and 30. The simulation investigates the relative performance of conditional cooperative strategies with increasing group size. Results show that some 'nice' strategies like 'tit-for-tat' are relatively successful and robust even in larger groups and non-nice environments. However, this does not solve the cooperation problem. On the contrary, the relative success of some 'nice' conditional cooperative strategies is paralleled by a rapid decline of cooperation in large groups.