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The Preface from The Complexity of Cooperation by Robert Axelrod


This book is a sequel to the Evolution of Cooperation (Axelrod, 1984). That book had a single paradigm and a simple theme. The paradigm was the two-person iterated Prisoner's Dilemma. The theme was that cooperation based upon reciprocity can evolve and sustain itself even among egoists provided there is sufficient prospect of a long term interaction. The theme was developed from many different angles, including computer tournaments, historical cases, and mathematical theorems.

The two-person iterated Prisoner's Dilemma is the E. coli of the social sciences, allowing a very large variety of studies to undertaken in a common framework. It has even become a standard paradigm for studying issues in fields as diverse as evolutionary biology and networked computer systems. Its very simplicity has allowed political scientists, economists, sociologists, philosophers, mathematicians, computer scientists, evolutionary biologists, and many others to talk to each other. Indeed, the analytic and empirical findings about the Prisoner's Dilemma from one field have often led to insights in other fields.[1]

The Evolution of Cooperation, with its focus on the Prisoner's Dilemma, was written during the Cold War. Indeed, one of its primary motivations was to help promote cooperation between the two sides of a bi-polar world. My hope was that a deeper understanding of the conditions that promote cooperation could help make the world a little safer. The work was well received in strictly academic circles, and even among scholars interested in policy-relevant research.[2] Nevertheless, I was keenly aware that there was a lot more to cooperation than could be captured by any single model, no matter how broad its applications or how rich its strategic implications.

The present book is based on a series of studies that go beyond the basic paradigm of the Prisoner's Dilemma. It includes an analysis of strategies that evolve automatically, rather than by human invention. It also considers strategies designed to cope with the possibility of misunderstandings between the players or misimplementation of a choice. It then expands the basis of cooperation to be more than a choice with a short-run cost and a possible long run gain. It includes collaboration with others to build and enforce norms of conduct, to win a war or to impose an industrial standard, to build a new organization that can act on behalf of its members, and to construct a shared culture based on mutual influence.

Expansion of the potential forms of collaboration implies the expansion of the potential forms of competition. The present volume therefore considers more than whether or not two players cooperate. It includes the conflicts between violators and enforcers of a norm, the threats and wars among nations, competition among companies, contests among organizations for wealth and membership, and competing pulls of social influence for cultural change.

This book includes work done from 1986 to 1996, a period in which the Cold War was coming to an end, and a new era was taking shape. My own research agenda was deeply affected by these dramatic and unexpected transformations. The transformations of this decade were especially salient because during this period I was fortunate to have opportunities to participate in international activities aimed at promoting cooperation, first between the United States and the Soviet Union, and then among the various warring groups in the former Yugoslavia. It is ironic that my theoretical work on two-person games led to my participation in international activities just as the bi-power world of the Cold War was coming to an end.

In 1986, I joined a committee of the National Academy of Sciences examining the relevance of behavioral and social sciences to the prevention of nuclear war. Among other projects, this committee promoted parallel or collaborative research with Soviet scholars on topics of mutual interest.

My participation in this committee also led to my joining a second committee of the National Academy of Sciences, the Committee on International Security and Arms Control. This committee consisted mostly of physical scientists, and worked with a counterpart Soviet group. Our mission was to consider fruitful avenues for arms control initiatives that would go beyond what was currently being negotiated between the two governments. Among the members were scientists with decades of experience in arms control, and a former Chairman of the Joint Chiefs of Staff. The Soviet counterpart committee included several key science advisors to the Soviet leader, Mikhail Gorbachev.

Participating in these social science and arms control forums taught me a great deal about how international politics was viewed by leading scholars and policy activists. In particular, I was impressed by the intellectual efforts of leading thinkers on both sides to formulate concepts and recommendations that would capitalize on the new opportunities of the era, as well as deal with the new dangers of instability. The difficulties faced by these talented, experienced and practical leaders reinforced my own faith in the potential value of research into fundamental political and social processes.

I was also affected by what was happening outside our committee meetings. Our work brought me to meetings in Uzbekistan in 1988 and Estonia in 1989, as well as Russia. In Estonia, I asked our Soviet hosts if they could find a way for us to meet with both the Estonian nationalists, who were then accelerating their demands for independence, and the ethnic Russians who opposed them. Having them meet in one room was impossible, I was politely told, but separate meetings were arranged for our benefit. This gave me a first hand feel for the depth of nationalist sentiment, and heightened my interest in cultural conflict and nationalism as fundamental forces in the world. These interests in turn led to work included in this book on how new political actors are formed, and how social influence promotes cultural change as the foundation of political change.

In 1989, however, I accepted the validity of quip that if it came to a conflict between Estonia and Moscow, the winner would be the Red Army. Yet within two years the Soviet Union had collapsed, and Estonia as well as all the other republics had their independence.

As democracy was developing in Russia, Yugoslavia disintegrated. In Bosnia, a bitter civil war ensued, marked by a level of atrocities not seen in Europe for fifty years. At the height of the fighting, in the summer of 1995, I was invited by the United Nations to talk about my work on cooperation at a conference designed to bring together non-governmental representatives of all the warring factions in the former Yugoslavia. The participants had many critical questions about how my Prisoner's Dilemma work applied to the complexity of their conflicts, with its unequal power, with fifteen rather than two sides to the conflicts, and with violations of widely held norms of conduct.

Many of the issues raised by the participants were ones on which I had been actively working. While I did not have simple answers to these questions, I had been working on many of these very issues. The present volume includes models that deal with unequal power, with multi-sided as well as two- sided conflict, with misunderstandings and misimplementions, with the enforcement of norms, with newly emerging political entities, and with the cultural basis for political affiliation and polarization. While I have no solutions, I believe that analyzing how the interactions of actors lead to large-scale outcomes can enhance our understanding of conflict and cooperation in a complex world.

Most of the chapters in this book were first published in journals and edited volumes of political science, conflict studies, organizational science, and computer science. The separate articles originally appeared in a such a wide range of places that people who may have read one or two of them are unlikely to be aware of the others. Publishing these articles as a collected set may be of special value to three partly overlapping groups of readers: those who want to learn about extensions to the two-person Prisoner's Dilemma, those who are interested in conflict and collaboration in a variety of settings, and those who are interested in agent-based modeling in the social sciences.

To place the work in a wider context, I have added a variety of new material:

1. An introductory chapter describing the common themes of the volume, and showing how the individual chapters relate to each other,

2. Introductory material for each chapter showing how it grew out of my long-term interests, recounting experiences related to the project, and describing how the work was received.

3. An appendix providing resources for students and scholars who wish to do their own agent-based modeling.

With the supplementary material, the volume should be accessible an advanced undergraduate interested in fundamental aspects of political and social change. Readers unfamiliar with the iterated Prisoner's Dilemma may wish to consult any standard game theory text, or Axelrod (1984, p.1-15). In the few places where specialized knowledge is used, the argument is also explained in simpler terms.

With pleasure, I acknowledge the encouragement and helpful criticism of the BACH research group: Arthur Burks, Michael Cohen, John Holland, Rick Riolo, and Carl Simon. It has been an education, a joy, and an honor to have been part of the BACH group for well over a decade. For editorial help with this volume, I would like to thank Amy Saldinger. I would also like to thank all those people and institutions who helped with chapters of this book. Their names are given in the appropriate places. Finally, for financial help in completing this book, I would like to thank the Defense Advanced Project Research Agency for its assistance through the Santa Fe Institute, and The University of Michigan for its assistance through both the LS&A College Enrichment Fund and the School of Public Policy.


Axelrod, Robert. 1984. The Evolution of Cooperation. NY: Basic Books.

_____ and Lisa D'Ambrosio, 1995. "Announcement for Bibliography on the Evolution of Cooperation," Journal of Conflict Resolution, 39, 190.

_____ and Douglas Dion, 1988. "The Further Evolution of Cooperation," Science, 242 (9 December), 1385-1390.

[1]For reviews see Axelrod and Dion (1988), and Axelrod and D'Ambrosio (1995).

[2]For example, in 1990, I received the National Academy of Sciences' new Award for Behavioral Research Relevant to the Prevention of Nuclear War. On the Soviet side, several senior defense intellectuals and scientists involved in arms control policy reported that they read the book with interest, and had passed it around to their friends.

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Revised November 4, 1996.