Michael W. Macy
Goldwin Smith Professor of Arts and Sciences
Department of Sociology
Department of Information Science
Director, Social Dynamics Laboratory
Cornell University
Ithaca, NY 14853
Voice: (607) 255-4555
Fax: (607) 202-4913
Email: mwm14@cornell.edu

Why does our world not degenerate into the world of Mad Max -- and why does it sometimes seem as if it may? Social order among interdependent agents can be imposed "from above" by a global policing mechanism or it can emerge "from below" through local interactions among adaptive agents with no centralized coordination. Suppose no member of the population has the ability to identify or impose a global solution. How then is social order possible? The motivating problem is one that defines the human condition: the overwhelming need for norms that constrain aggressive and mutually destructive behavior is no guarantee that such rules will emerge or be obeyed by anyone except a few "suckers." On the contrary, norms can even make matters worse, by obligating people to engage in behaviors that are individually and collectively harmful (e.g., pressuring one's neighbors to support various "naked emperors"). It is not hard to explain why people comply with socially undesirable norms in the face of social pressure, but why would a skeptical population enforce these norms in the first place? Why do people use political and cultural beliefs and behaviors like bumper stickers that signal community membership? And why are political views on taxes and spending highly correlated with views on same-sex marriage, gun control, reproductive rights, and consumer preferences like Prius, Dodge Ram, lattes, and "The Walking Dead"?

Our research team uses computational models, laboratory experiments with human subjects, and digital traces from online networks to look for elementary principles of human behavior and social interaction that may yield clues about possible answers to these and related puzzles about social order and conflict. For example, the video below is based on a computational model of selective influence that suggests a simple explanation for political and cultural polarization: people are attracted to those with similar beliefs, repelled by those with salient differences, and are positively and negatively influenced by those to whom they are attracted/repelled. The model consists of 100 fully connected agents with initially random traits on 10 cultural features. The axes displayed above are the two principle eigenvectors from the 10-dimensional sociomatrix. The size of the circle indicates the number of agents with that cultural profile. Multiple runs show how the dynamics of social influence, homophily, and xenophobia can lead to cultural polarization, such that agents at each pole have identical traits on all ten cultural features and are maximally dissimilar to the agents at the opposite pole. Thus, from a random start, all 45 pairwise cultural dimensions come to be highly correlated, but the signs of the correlations are in all cases entirely arbitrary. Incomplete polarization is also possible, with agents aligned on a small number of cross-cutting dimensions.

An Attractor Neural Network Model of Cultural Polarization 

This simple toy model yields a number of hypotheses about how norms, beliefs, emotions, and collective behaviors might emerge and spread through local interaction. These hypotheses have motivated empirical studies including the spread of "complex contagions" that depend on social reinforcement from several network neighbors, the willingness to "pay it forward," political polarization in cultural consumption (including science books), the discovery of “social wormholes” that span large network distances, the "mesh of civilizations," and similarity in diurnal and seasonal mood variations across diverse cultures.

Click here for Networks and Social Dynamics at Cornell

Click here for Nature feature story by Jim Giles on computational social science at Cornell

Click here for iTunes U video on "Getting Connected" at Cornell's Institute for the Social Sciences

Click here for Oct 2011 "Naked Scientist" interview on BBC

Click here for Seti Institute's "Big Picture Science" interview on Public Radio

Click here for March 2014 NY Times Op Ed "The Science of Paying It Forward"

Click here for Guardian article on "Partisan Consumption of Science"

Click here or here for "Science Friday" interview

Link to our lifestyle-politics.com website

Click here to download my CV

I have listed below some of my papers that you are welcome to download. Some papers require access to JSTOR or other archives; if your university does not provide access, please email me and I will send you a digital copy.

Peter Krafft, Michael Macy, Sandy Pentland
Proceedings of CSCW 2017

Chris Cameron and Michael Macy
Rationality and Society, March 2017

F. Bill Shi, Yongen Shi, Fedor Dokshin, James Evans and Michael Macy
Nature Human Behavior, April 12, 2017
Clay Fink, Aurora Schmidt, Vlad Barash, Chris Cameron, and Michael Macy
Social Network Analysis and Mining, December 2016, 6:1
Clay Fink, Aurora Schmidt, Vlad Barash, John Kelly, Chris Cameron, and Michael Macy.
2016 Proceedings of ICWSM
Yongren Shi and Michael Macy
Social Science Research 2016
Wei Dong, Kate Ehrlich, Michael Macy, and Michael Muller
Proceedings of CSCW 2016
Daniel DellaPosta and Michael Macy
In Order on the Edge of Chaos, Cambridge University Press, 2016

Why Do Liberals Drink Lattes?
Daniel Della Posta, Yongren Shi, and Michael Macy
American Journal of Sociology, March, 2015

The Mesh of Civilizations in the Global Network of Digital Communication
Bogdan State, Patrick Park, Ingmar Weber, and Michael Macy
PLOS ONE, May 29, 2015

The Social Contagion of Anti-Social Behavior
Milena Tsvetkova and Michael Macy
Sociological Science, Feb. 10, 2015

Big Theory: A Trojan Horse for Economics?
Michael Macy
Review of Behavioral Economics 2014

The Signal Importance of Noise
Michael Macy and Milena Tsvetkova
Sociological Methods and Research 2015

Digital Footprints: Opportunities and Challenges for Social Research
Scott Golder and Michael Macy
Annual Review of Sociology, Vol. 40, 2014

The Social Contagion of Generosity
Milena Tsvetkova and Michael Macy
PLOS One Feb. 13, 2014: 9(2): e87275

Statistical Mechanics and Social Sciences
Santo Fortunato, Michael Macy, Sidney Redner
Journal of Statistical Physics 2013, 151:1-8

Critical Phenomena in Complex Contagions
Vladimir Barash, Chris Cameron, and Michael Macy
Social Networks 2012, 34:451-61

Diurnal and Seasonal Mood Vary with Work, Sleep and Daylength Across Diverse Cultures
Scott Golder and Michael Macy
Science 2011, 333:1878-81

Small Worlds and Cultural Polarization
Andreas Flache and Michael Macy
Journal of Mathematical Sociology 2011, 34: 146-76

Local Convergence and Global Diversity: From Interpersonal to Social

Andreas Flache and Michael Macy
Journal of Conflict Resolution 2011, 55: 970-95

Network Diversity and Economic Development
Nathan Eagle, Rob Claxton, and Michael Macy
Science 2010, 328: 1029-1031

Computational Social Science
David Lazer et al.
Science 2009, 323: 712-723

The False Enforcement of Unpopular Norms
Rob Willer, Ko Kuwabara, and Michael Macy
American Journal of Sociology 2009, 115:451-490

Neighborhood Chance and Neighborhood Change
Arnout Van de Rijt, David Siegel, and Michael Macy
American Journal of Sociology 2009, 114:1166-80

Complex Contagions and the Weakness of Long Ties
Damon Centola and Michael Macy
American Journal of Sociology 2007, 113:702-34

Culture, Identity, and Structure in Social Exchange: A Web-based Trust Experiment in the U.S. and Japan
Kuwabara, K., R. Willer, M. Macy, R. Mashima, S. Terai, and T. Yamagishi
Social Psychology Quarterly, 2007, 70:461-79

Collective Action and the Empirical Content of Stochastic Learning Models
M. Macy and A. Flache
American Journal of Sociology, 2007, 112: 1546-54

Cascade Dynamics of Complex Propagation
Damon Centola, Victor M. Eguiluz, and Michael Macy
Physica A 2007, 374: 449-456

Power and Dependence in Intimate Exchange
Arnout van de Rijt, and Michael Macy
Social Forces 2006, 84:1455-70

Ethnic Preferences and Residential Segregation: Theoretical Explorations Beyond Detroit
Michael Macy and Arnout van de Rijt
Journal of Mathematical Sociology 2006, 30: 275-88

The Emperor's Dilemma: A Computational Model of Self-Enforcing Norms
Damon Centola, Robb Willer, and Michael Macy
American Journal of Sociology 2005, 110:1009-40

Social Life in Silico: The Science of Artificial Societies
Damon Centola and Michael Macy
Handbook of Group Research and Practice 2005, pp. 273-2812

Power, Identity, and Collective Action in Social Exchange
Brent Simpson and Michael Macy
Social Forces, June, 2004.

Polarization in Dynamic Networks: A Hopfield Model of Emergent Structure
Michael Macy, James Kitts, Andreas Flache, and Steve Benard
Dynamic Social Network Modeling and Analysis, National Academy Press, 2003

Learning Dynamics in Social Dilemmas
Michael Macy and Andreas Flache
Proceedings of the National Academy of Sciences, May 14, 2002.

Stochastic Collusion and the Power Law of Learning
Andreas Flache and Michael Macy
Journal of Conflict Resolution, October, 2002

From Factors to Actors: Computational Sociology and Agent-Based Modeling
Michael Macy and Robert Willer
Annual Review of Sociology, Vol. 28, 2002

Trust and Market Formation in the U.S. and Japan
Michael Macy and Yoshimichi Sato
Proceedings of the National Academy of Sciences, April, 2002
Source code for the computational model

Social Simulation
Michael W. Macy
In N. Smelser and P. Baltes, eds., International Encyclopedia of the Social and Behavioral Sciences, Elsevier, 2002

Dependence and Cooperation in Fuzzy Dilemmas
R. Thomas Boone and Michael W. Macy
In R. Suleiman, D. Budescu, & D. Messick, eds., ContemporaryPsychological Research on Social Dilemmas
Cambridge University Press, 2002.

'In Search ofExcellence': Fads, Success Stories, and Adaptive Emulation*
David Strang and Michael Macy
Best Paper Proceedings of the 1999 Academy of Management Conference, Chicago,IL
American Journal of Sociology, July, 2001.

Collective Action and Power Inequality: Coalitions in Exchange Networks
Brent Simpson and Michael Macy
Social Psychology Quarterly, March, 2001.

Structural Learning: Attraction and Conformity in Task-Oriented Groups
James Kitts, Michael Macy, and Andreas Flache
Computational and Mathematical Organization Theory, 1999, vol. 5(2):129-45.

Unlocking the Doors to Prisoners Dilemma: Dependence, Selectivity, and Cooperation
R. Thomas Boone and Michael Macy
Social Psychology Quarterly 1999, 62: 32-52.

The Evolution of Trust and Cooperation between Strangers: A Computational Model
Michael Macy and John Skvoretz
American Sociological Review, October, 1998

Social Order and Emergent Rationality
Michael Macy
In A. Sica, ed. Whatis Social Theory: The Philosophical Debates, 1998, Blackwell.

Dependence and Cooperation in the Game of Trump
R. Thomas Boone and Michael Macy
Advances in Group Processes, vol. 15, 1998

Social Order in an Artificial World
Michael W. Macy
Journal of Artificial Societies and Social Simulation, January, 1998.

Identity, Interest, and Emergent Rationality: An Evolutionary Synthesis
Michael Macy
Rationality and Society, vol. 9, 1997.

The Weakness of Strong Ties: Collective Action Failure in a Highly Cohesive Group
Andreas Flache and Michael W. Macy
Journal of Mathematical Sociology, June, 1996

Natural Selection and Social Learning in Prisoner's Dilemma: Co-adaptationwith Genetic Algorithms and Artificial Neural Networks
Michael W. Macy
Sociological Methods and Research, Vol 25, August, 1996, pp. 103-137

Beyond Rationality in Models of Choice
Michael W. Macy and Andreas Flache
Annual Review of Sociology, Vol. 21, 1995

PAVLOV and the Evolution of Cooperation: An Experimental Test
Michael W. Macy
Social Psychology Quarterly, June, 1995

Artificial Social Intelligence
William Bainbridge, Edward Brent, David Heise, Michael Macy, Barry Markovsky, & John Skvoretz
Annual Review of Sociology, Vol. 21, 1995

Once Upon a Time There Was a Suboptimal Equilibrium
Michael W. Macy
The Agora, June, 1996

Cowardly Lions: Genetic Programming or Social Learning?
Michael W. Macy
The Agora, December, 1995

Social Class
Michael W. Macy
The Encyclopedia of Language and Linguistics

Backward-Looking Social Control
Michael W. Macy
American Sociological Review, 1993, Vol. 58:819-36.

Chains of Cooperation: Threshold Effects in Collective Action
Michael W. Macy
American Sociological Review, 1991, Vol. 56:730-47.

Learning to Cooperate: Stochastic and Tacit Collusion in Social Exchange
Michael W. Macy
American Journal of Sociology, 1991, Vol. 97:808-43.

Learning Theory and the Logic of Critical Mass
Michael W. Macy
American Sociological Review, 1990, Vol. 55:809-26.

Value Theory and the Golden Eggs: Appropriating the Magic of Accumulation
Michael W. Macy
Sociological Theory, 1988, Vol. 6: 131-52.

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