Princeton Studies in Complexity

Michael Laver is professor of politics at New York University. He is the coauthor of Multiparty Government: The Politics of Coalition in Europe. Ernest Sergenti is a consultant at the World Bank. Party competition for votes in free and fair elections involves complex interactions by multiple actors in political landscapes that are continuously evolving, yet classical theoretical approaches to the subject leave many important questions unanswered. Here Michael Laver and Ernest Sergenti offer the first comprehensive treatment of party competition using the computational techniques of agent-based modeling. This exciting new technology enables researchers to model competition between several different political parties for the support of voters with widely varying preferences on many different issues. Laver and Sergenti model party competition as a true dynamic process in which political parties rise and fall, a process where different politicians attack the same political problem in very different ways, and where today's political actors, lacking perfect information about the potential consequences of their choices, must constantly adapt their behavior to yesterday's political outcomes. Party Competition shows how agent-based modeling can be used to accurately reflect how political systems really work. It demonstrates that politicians who are satisfied with relatively modest vote shares often do better at winning votes than rivals who search ceaselessly for higher shares of the vote. It reveals that politicians who pay close attention to their personal preferences when setting party policy often have more success than opponents who focus solely on the preferences of voters, that some politicians have idiosyncratic "valence" advantages that enhance their electability--and much more. "[T]he book is an excellent starting point for everyone interested in party competition and provides food for future agent-based research."---Víctor M. Eguíluz, JASSS "Besides political scientists who are interested in the topic, this book is well suited for any social scientist who looks for an exemplary introduction to basic techniques of simulation-based research."---Johannes Zschache, RMM "This is a rich and provocative book. . . . For methodologically sophisticated political scientists, and especially those interested in spatial analysis, this is no doubt the best introduction available to the challenging, exciting, and, to many, still mysterious worlds of agent-based modeling."---Charles H. Blake, Perspectives on Politics "Laver and Sergenti argue that politics is best viewed as a complex dynamical system that is neither random nor in equilibrium. Their use of agent-based modeling to better understand the flux of politics will be of great interest to the next generation of modelers seeking to make sense of the wide variety of political systems in the real world."-Norman Schofield, Washington University in St. Louis "Laver and Sergenti present a bold and rigorous new approach to interparty electoral competition. Their results are remarkable and often puzzling, offering plentiful food for thought for modelers, analytical theorists, and empiricists alike. Ignore this book at your peril, or better, read it and become an admirer."-Kaare Strøm, University of California, San Diego "Party Competition is an ambitious and pioneering work. Laver and Sergenti present a new methodology for the study of a quite central and traditional problem in political science. This is to my knowledge the first book-length treatise on the evolutionary modeling of party competition."-Hannu Nurmi, author of Models of Political Economy "Distinct and important. The tools that Laver and Sergenti bring to bear on computational modeling will start a debate that is long overdue in the social sciences. This is another step forward in developing the methods needed to solve real-world problems that have so far resisted our best efforts."-Scott de Marchi, Duke Unive

Lars-Erik Cederman is University Lecturer in International Relations at Somerville College, University of Oxford. He has written for such publications as International Organization, International Studies Quarterly, and European Journal of International Relations. The disappearance and formation of states and nations after the end of the Cold War have proved puzzling to both theorists and policymakers. Lars-Erik Cederman argues that this lack of conceptual preparation stems from two tendencies in conventional theorizing. First, the dominant focus on cohesive nation-states as the only actors of world politics obscures crucial differences between the state and the nation. Second, traditional theory usually treats these units as fixed. Cederman offers a fresh way of analyzing world politics: complex adaptive systems modeling. He provides a new series of models--not ones that rely on rational-choice, but rather computerized thought-experiments--that separate the state from the nation and incorporate these as emergent rather than preconceived actors. This theory of the emergent actor shifts attention away from the exclusively behavioral focus of conventional international relations theory toward a truly dynamic perspective that treats the actors of world politics as dependent rather than independent variables. Cederman illustrates that while structural realist predictions about unit-level invariance hold up under certain circumstances, they are heavily dependent on fierce power competition, which can result in unipolarity instead of the balance of power. He provides a thorough examination of the processes of nationalist mobilization and coordination in multi-ethnic states. Cederman states that such states' efforts to instill loyalty in their ethnically diverse populations may backfire, and that, moreover, if the revolutionary movement is culturally split, its identity becomes more inclusive as the power gap in the imperial center's favor increases. "Cederman presents an exhaustively researched, precisely orchestrated study using complex adaptive system computer modelling in an attempt to simulate emergent political actors and nationalism. It is an outstanding work, and Lars-Erik Cederman has earned a place on the bookshelf of every serious IR student." "This is an impressive and very original work, which takes up some of the most important and timely issues in the study of international relations and the emergence of nations and states. It opens up a very promising avenue for theoretical development by proposing a fresh solution to some of the basic epistemological problems of traditional positivistic studies of international relations."-Jack L. Snyder, Institute of War and Peace Studies, Columbia University

Agent-based computational modeling is changing the face of social science. In Generative Social Science, Joshua Epstein argues that this powerful, novel technique permits the social sciences to meet a fundamentally new standard of explanation, in which one "grows" the phenomenon of interest in an artificial society of interacting agents: heterogeneous, boundedly rational actors, represented as mathematical or software objects. After elaborating this notion of generative explanation in a pair of overarching foundational chapters, Epstein illustrates it with examples chosen from such far-flung fields as archaeology, civil conflict, the evolution of norms, epidemiology, retirement economics, spatial games, and organizational adaptation. In elegant chapter preludes, he explains how these widely diverse modeling studies support his sweeping case for generative explanation. This book represents a powerful consolidation of Epstein's interdisciplinary research activities in the decade since the publication of his and Robert Axtell's landmark volume, “Growing Artificial Societies.”

"Winner of the Don K. Price Award, Science, Technology & Environmental Politics Section of the American Political Science Association" Louise K. Comfort is professor at the Graduate School of Public and International Affairs and former director of the Center for Disaster Management at the University of Pittsburgh. Her previous books include Shared Risk: Complex Systems in Seismic Response. Earthquakes are a huge global threat. In thirty-six countries, severe seismic risks threaten populations and their increasingly interdependent systems of transportation, communication, energy, and finance. In this important book, Louise Comfort provides an unprecedented examination of how twelve communities in nine countries responded to destructive earthquakes between 1999 and 2015. And many of the book's lessons can also be applied to other large-scale risks. The Dynamics of Risk sets the global problem of seismic risk in the framework of complex adaptive systems to explore how the consequences of such events ripple across jurisdictions, communities, and organizations in complex societies, triggering unexpected alliances but also exposing social, economic, and legal gaps. The book assesses how the networks of organizations involved in response and recovery adapted and acted collectively after the twelve earthquakes it examines. It describes how advances in information technology enabled some communities to anticipate seismic risk better and to manage response and recovery operations more effectively, decreasing losses. Finally, the book shows why investing substantively in global information infrastructure would create shared awareness of seismic risk and make postdisaster relief more effective and less expensive. The result is a landmark study of how to improve the way we prepare for and respond to earthquakes and other disasters in our ever-more-complex world. "By examining how some countries develop earthquake modeling systems that work while others don't, this book illuminates how coherence and resilience are designed."-Jane E. Fountain, University of Massachusetts Amherst "The culmination of years of careful field and empirical analytical work, this is an important book on a timely and significant issue of public policy."-Todd R. LaPorte, professor emeritus, University of California, Berkeley "The Dynamics of Risk is an excellent account of seismic risk from a complex systems perspective. The book presents a comprehensive theoretical framework that embeds myriad case studies that reveal how a lack of preparedness and adaptability hindered responses. A magnificent work of scholarship demonstrating the value of complex systems to policy."-Scott E. Page, University of Michigan "Analyzing the ability of response systems to adapt to the dynamics of major recent earthquakes, this book produces fundamental new knowledge and insights for the development of resilient societies."-Friedemann Wenzel, Karlsruhe Institute of Technology, Germany

John H. Miller is professor of economics and social sciences at Carnegie Mellon University. Scott E. Page is professor of complex systems, political science, and economics at the University of Michigan. He is the author of The Difference (Princeton). This book provides the first clear, comprehensive, and accessible account of complex adaptive social systems, by two of the field's leading authorities. Such systems--whether political parties, stock markets, or ant colonies--present some of the most intriguing theoretical and practical challenges confronting the social sciences. Engagingly written, and balancing technical detail with intuitive explanations, Complex Adaptive Systems focuses on the key tools and ideas that have emerged in the field since the mid-1990s, as well as the techniques needed to investigate such systems. It provides a detailed introduction to concepts such as emergence, self-organized criticality, automata, networks, diversity, adaptation, and feedback. It also demonstrates how complex adaptive systems can be explored using methods ranging from mathematics to computational models of adaptive agents. John Miller and Scott Page show how to combine ideas from economics, political science, biology, physics, and computer science to illuminate topics in organization, adaptation, decentralization, and robustness. They also demonstrate how the usual extremes used in modeling can be fruitfully transcended. "The use of computational, especially agent-based, models has already shown its value in illuminating the study of economic and other social processes. Miller and Page have written an orientation to this field that is a model of motivation and insight, making clear the underlying thinking and illustrating it by varied and thoughtful examples. It conveys with remarkable clarity the essentials of the complex systems approach to the embarking researcher."-Kenneth J. Arrow, winner of the Nobel Prize in economics "In Complex Adaptive Systems, two masters of this burgeoning field provide a highly readable and novel restatement of the logic of social interactions, linking individually based micro processes to macrosocial outcomes, ranging from Adam Smith's invisible hand to Thomas Schelling's models of standing ovations. The book combines the vision of a new Santa Fe school of computational, social, and behavioral science with essential 'how to' advice for apprentice modelers."-Samuel Bowles, author of Microeconomics: Behavior, Institutions, Evolution "This is a wonderful book that will be read by graduate students, faculty, and policymakers. The authors write in an extraordinarily clear manner about topics that are very technical and difficult for many people. I sat down to begin thumbing through and found myself deeply engaged."-Elinor Ostrom, author of Understanding Institutional Diversity

Joshua M. Epstein directs the Center for Advanced Modeling at The Johns Hopkins University, where he is a professor in the Department of Emergency Medicine with joint appointments in the Departments of Applied Mathematics, Economics, International Health, Environmental Health Sciences, Biostatistics, Civil Engineering, and the Institute for Computational Medicine. He is also an external professor at the Santa Fe Institute. This volume forms a trilogy on agent-based modeling, with Growing Artificial Societies: Social Science from the Bottom Up (MIT), with coauthor Robert Axtell, and Generative Social Science: Studies in Agent-Based Computational Modeling (Princeton). The Final Volume of the Groundbreaking Trilogy on Agent-Based Modeling In this pioneering synthesis, Joshua Epstein introduces a new theoretical entity: Agent_Zero. This software individual, or "agent," is endowed with distinct emotional/affective, cognitive/deliberative, and social modules. Grounded in contemporary neuroscience, these internal components interact to generate observed, often far-from-rational, individual behavior. When multiple agents of this new type move and interact spatially, they collectively generate an astonishing range of dynamics spanning the fields of social conflict, psychology, public health, law, network science, and economics. Epstein weaves a computational tapestry with threads from Plato, Hume, Darwin, Pavlov, Smith, Tolstoy, Marx, James, and Dostoevsky, among others. This transformative synthesis of social philosophy, cognitive neuroscience, and agent-based modeling will fascinate scholars and students of every stripe. Epstein's computer programs are provided in the book or on its Princeton University Press website, along with movies of his "computational parables.? Agent_Zero is a signal departure in what it includes (e.g., a new synthesis of neurally grounded internal modules), what it eschews (e.g., standard behavioral imitation), the phenomena it generates (from genocide to financial panic), and the modeling arsenal it offers the scientific community. For generative social science, Agent_Zero presents a groundbreaking vision and the tools to realize it. "Agent Zero offers a solution to some of social science's great puzzles. Its behavioral basis is the interplay of emotion, cognition, and network contagion effects. It elegantly explains why so many human actions are so manifestly dysfunctional, and why some are downright evil."-George Akerlof, Nobel Laureate in Economics "Rarely has a book stimulated me intellectually as much as this one. Particularly exciting is the incorporation of agents who feel (affect) and deliberate, as well as influence one another through social interaction. Epstein is a brilliantly creative scholar and the range of applications showcased here is stunning. In sum, this is a pathbreaking book."-Paul Slovic, University of Oregon "Joshua Epstein proposes a parsimonious but powerful model of individual behavior that can generate an extraordinary range of group behaviors, including mob violence, manias and financial panics, rebellions, network dynamics, and a host of other complex social phenomena. This is a highly original, beautifully conceived, and important book."-Peyton Young, University of Oxford "In social science generally and most notably in economics, the rational actor model has long been the benchmark for policy analysis and institutional design. Epstein now offers a worthy alternative: Agent_Zero, a mathematically and computationally tractable agent whose inner workings are grounded in neuroscience. Much like you and me, Agent_Zero is influenced by emotion, reason, and social pressures. Epstein demonstrates that collections of Agent Zeros perform amazingly like real groups, teams, and societies and can therefore serve as the fundamental building blocks for what he calls Generative Social Science. The rational actor now has a true competitor. Agent_Zero is a major advance."-S

"One of Choice's Outstanding Academic Titles for 2009" Marten Scheffer is professor of environmental sciences at Wageningen University in the Netherlands. He is the author of Ecology of Shallow Lakes. How do we explain the remarkably abrupt changes that sometimes occur in nature and society--and can we predict why and when they happen? This book offers a comprehensive introduction to critical transitions in complex systems--the radical changes that happen at tipping points when thresholds are passed. Marten Scheffer accessibly describes the dynamical systems theory behind critical transitions, covering catastrophe theory, bifurcations, chaos, and more. He gives examples of critical transitions in lakes, oceans, terrestrial ecosystems, climate, evolution, and human societies. And he demonstrates how to deal with these transitions, offering practical guidance on how to predict tipping points, how to prevent "bad" transitions, and how to promote critical transitions that work for us and not against us. Scheffer shows the time is ripe for understanding and managing critical transitions in the vast and complex systems in which we live. This book can also serve as a textbook and includes a detailed appendix with equations. • Provides an accessible introduction to dynamical systems theory • Covers critical transitions in lakes, oceans, terrestrial ecosystems, the climate, evolution, and human societies • Explains how to predict tipping points • Offers strategies for preventing "bad" transitions and triggering "good" ones • Features an appendix with equations "This excellent, well-crafted volume outlines theoretical/applied evidence describing regime shifts that occur in natural and societal systems, and suggests how to address deleterious change to further human welfare. Scheffer expertly argues that system shifts are critical transitions arising when normal cyclical processes are stressed, thereby generating 'tipping points'. . . . A highly important book of intellectual and applied significance."---M. Evans, Choice "Scheffer's book is a good read. It is fluently written and breathes authority, while still being highly consistent in its terminology."---Carsten F. Dormann, Basic and Applied Ecology "We recommend this book as the best integration of the multiple rubrics (resilience, regime change, panarchy, complexity, dynamical systems theory) found on the subject of critical transitions or abrupt change, and as an enjoyable as well as enlightening synthesis of a timely and important topic bearing on many of the crucial dilemmas of our time."---William A. Reiners, Ecology "The marvelous Scheffer's book is strongly recommended for all geoscientists because of three main reasons. First, it explains the outstanding importance of critical transitions in the abiotic, biotic, and social evolution and establishes a helpful framework for their further studies. Second, this book gives an exceptional opportunity to realize how broad, even philosophical treatment of very particular ideas can facilitate development of the tatters. Third, the author was very successful in demonstration of how do general laws work in the both nature and society. This unconventional book is very informative, well-written, and stimulating, and, consequently, nobody will lose her/his time reading it."---Dmitry A. Ruban, Zentralblatt fur Geologie und Palaontologie "This is an important book. Critical transitions and resilience are powerful explanatory tools in ecology today, and it is significant that Scheffer, the leading expert in the applications of critical transitions in ecology, has written a monograph in this area. Scheffer is an excellent writer, and a very good expositor of theoretical concepts in ecology. The ideas in this book should be part of every educated person's mental framework."-Donald L. DeAngelis, University of Miami "This is a timely book that will have considerable impact on multiple disciplines, including ecology,

J. Stephen Lansing is Director of the Complexity Institute and Professor in the Asian School of the Environment at Nanyang Technological University in Singapore. His books include Perfect Order: Recognizing Complexity in Bali (Princeton). Murray P. Cox is Professor of Computational Biology at Massey University in New Zealand. Two pioneering anthropologists reveal how complexity science can help us better understand how societies change over time Over the past two decades, anthropologist J. Stephen Lansing and geneticist Murray Cox have explored dozens of villages on the islands of the Malay Archipelago, combining ethnographic research with research into genetic and linguistic markers to shed light on how these societies change over time. Islands of Order draws on their pioneering fieldwork to show how the science of complexity can be used to better understand unstable dynamics in culture, language, cooperation, and the emergence of hierarchies. Complexity science has opened exciting new vistas in physics and biology, but poses challenges for social scientists. What triggers fundamental, discontinuous social change? And what brings stable patterns-islands of order-into existence? Lansing and Cox begin with an incisive and accessible introduction to models of change, from simple random drift to coupled interactions, phase transitions, co-phylogenies, and adaptive landscapes. Then they take readers on a series of journeys to the islands of the Indo-Pacific to demonstrate how social scientists can harness these powerful tools to discover out-of-equilibrium social dynamics. Lansing and Cox address empirical questions surrounding the colonization of the Pacific, the relationship of language to culture, the emergence and disappearance of male and female hierarchies, and more. Unlocking new possibilities for the social sciences, Islands of Order is accompanied by an interactive companion website that enables readers to explore the models described in the book. "A major achievement. The breadth and depth of this brilliant book, from rich ethnography to elaborate agent-based models, are awe inspiring and standard setting."-Scott E. Page, author of The Diversity Bonus: How Great Teams Pay Off in the Knowledge Economy "This exceptional book is chock-full of ideas that can inspire a new generation of researchers in the study of human societies using the framework of complex systems."-Mark Moritz, Ohio State University

Robert Axelrod is the Arthur W. Bromage Distinguished University Professor of Political Science and Public Policy at the University of Michigan. His work on cooperation and norms has received awards from the American Association for the Advancement of Science, the American Political Science Association, the MacArthur Foundation, and the National Academy of Sciences. Robert Axelrod is widely known for his groundbreaking work in game theory and complexity theory. He is a leader in applying computer modeling to social science problems. His book The Evolution of Cooperation has been hailed as a seminal contribution and has been translated into eight languages since its initial publication. The Complexity of Cooperation is a sequel to that landmark book. It collects seven essays, originally published in a broad range of journals, and adds an extensive new introduction to the collection, along with new prefaces to each essay and a useful new appendix of additional resources. Written in Axelrod's acclaimed, accessible style, this collection serves as an introductory text on complexity theory and computer modeling in the social sciences and as an overview of the current state of the art in the field. The articles move beyond the basic paradigm of the Prisoner's Dilemma to study a rich set of issues, including how to cope with errors in perception or implementation, how norms emerge, and how new political actors and regions of shared culture can develop. They use the shared methodology of agent-based modeling, a powerful technique that specifies the rules of interaction between individuals and uses computer simulation to discover emergent properties of the social system. The Complexity of Cooperation is essential reading for all social scientists who are interested in issues of cooperation and complexity. "Robert Axelrod's extraordinary book, The Evolution of Cooperation was globally acclaimed for the rich results of its simple model. The Complexity of Cooperation now gathers together the myriad fruits of more than a decade's work, carefully 'complexifying' his initial model. Like his ideas, his prose is clear and engaging. His delight as he unveils each surprising discovery is infectious. This book is not merely important; it's fun."-Robert D. Putnam, author of Making Democracy Work

"Winner of the 2007 Julian Steward Book Award, Anthropology and Environment Section of the American Anthropological Association" J. Stephen Lansing is professor of anthropology at the University of Arizona, external professor at the Santa Fe Institute, and senior research fellow at the Stockholm Resilience Centre. He is the author of Priests and Programmers and The Balinese, and writer and codirector of documentary films such as Three Worlds of Bali and The Goddess and the Computer. Along rivers in Bali, small groups of farmers meet regularly in water temples to manage their irrigation systems. They have done so for a thousand years. Over the centuries, water temple networks have expanded to manage the ecology of rice terraces at the scale of whole watersheds. Although each group focuses on its own problems, a global solution nonetheless emerges that optimizes irrigation flows for everyone. Did someone have to design Bali's water temple networks, or could they have emerged from a self-organizing process? Perfect Order--a groundbreaking work at the nexus of conservation, complexity theory, and anthropology--describes a series of fieldwork projects triggered by this question, ranging from the archaeology of the water temples to their ecological functions and their place in Balinese cosmology. Stephen Lansing shows that the temple networks are fragile, vulnerable to the cross-currents produced by competition among male descent groups. But the feminine rites of water temples mirror the farmers' awareness that when they act in unison, small miracles of order occur regularly, as the jewel-like perfection of the rice terraces produces general prosperity. Much of this is barely visible from within the horizons of Western social theory. The fruit of a decade of multidisciplinary research, this absorbing book shows that even as researchers probe the foundations of cooperation in the water temple networks, the very existence of the traditional farming techniques they represent is threatened by large-scale development projects. "[A] winning combination of hard science and interpretative ethnography."---Roy Ellen, American Anthropologist "I would recommend . . . this book . . . as perhaps providing an example of social and ecological self-organization which might be useful in modeling other systems, whether in the social or ecological field or even in other fields in which complex adaptive systems may be studied."---Phillip Guddemi, Cybernetics & Human Knowing "A master story teller, Stephen Lansing is unique in his ability to explain order in human societies within the framework of complex systems theory. Through the lens of his Balinese study system, hierarchical organization, equality, and self-organization all become clearer. There are lessons in this book for understanding diverse societies, including our own."-Simon A. Levin, Princeton University, author of Fragile Dominion "The extraordinary complexity of Balinese social life, the grand variousness of its culture, and the clockwork precision of its terraced wet rice agriculture climbing up the sides of towering volcanoes have long astonished scholars, administrators, and tourists alike. In this brilliant synthesis, the anthropologist-cum-ecologist J. Stephen Lansing uncovers the principles which animate them and traces the ways in which they support and govern one another to produce a tremulous and troubled self-organizing, self-repairing whole. The collective management of irrigation, the endemic factionalism of village life, the fears and suspicions of the witches' and demons' spirit world, and the ritualized hierarchy of precedence and power are seen as conducing to a complicated common order precariously maintained. The result is something we have not had before-a comprehensive and circumstantial study of Bali as a whole. A major achievement."-Clifford Geertz, Institute for Advanced Study "Perfect Order is an exceptional work-a new classic in the anthropo

Peter Turchin is Professor of Ecology and Evolutionary Biology at the University of Connecticut. He is the author of Quantitative Analysis of Movement and Complex Population Dynamics (Princeton). Many historical processes are dynamic. Populations grow and decline. Empires expand and collapse. Religions spread and wither. Natural scientists have made great strides in understanding dynamical processes in the physical and biological worlds using a synthetic approach that combines mathematical modeling with statistical analyses. Taking up the problem of territorial dynamics--why some polities at certain times expand and at other times contract--this book shows that a similar research program can advance our understanding of dynamical processes in history. Peter Turchin develops hypotheses from a wide range of social, political, economic, and demographic factors: geopolitics, factors affecting collective solidarity, dynamics of ethnic assimilation/religious conversion, and the interaction between population dynamics and sociopolitical stability. He then translates these into a spectrum of mathematical models, investigates the dynamics predicted by the models, and contrasts model predictions with empirical patterns. Turchin's highly instructive empirical tests demonstrate that certain models predict empirical patterns with a very high degree of accuracy. For instance, one model accounts for the recurrent waves of state breakdown in medieval and early modern Europe. And historical data confirm that ethno-nationalist solidarity produces an aggressively expansive state under certain conditions (such as in locations where imperial frontiers coincide with religious divides). The strength of Turchin's results suggests that the synthetic approach he advocates can significantly improve our understanding of historical dynamics. "An important, original, and timely book-richly detailed and beautifully thought out."-Jack A. Goldstone, University of California, Davis "This book is clearly the state of the art in formal modeling and computer simulation of long-term historical changes in territorial states. Elegantly formulated and clearly written, it takes an important topic to a new level of formal sophistication."-Randall Collins, University of Pennsylvania