Revenge or Reconciliation?

Retribution or Reconciliation? Attitudes Toward Islamic State Collaborators, Principal Investigator, 2017-2023


Photo by Levi Clancy on Unsplash

Listen to a conversation about this work with Professor Ellen Lust, posted in the Governance Uncovered podcast series.

The Irredeemability of the Past: Determinants of Reconciliation and Revenge in Post-Conflict Settings

In the aftermath of violent conflict, identifying former enemy collaborators versus innocent bystanders forced to flee violence is extremely difficult. In many post-conflict settings, internally displaced persons (IDPs) risk becoming stigmatized and face difficulties reintegrating into society. This work considers the role of moral disapproval and future social value in processes of post-conflict reconciliation with stigmatized IDPs. We run experiments embedded within a large-N face-to-face survey across three areas of Iraq (n=4,500) that are experiencing the return of stigmatized IDPs, many of whom are suspected of having collaborated with the Islamic State in Iraq and Syria (ISIS). We find that immutable factors related to a stigmatized IDP’s past behavior, namely the severity of a transgression and the volition behind it, are the strongest predictors of both reconciliation and revenge. Transitional justice mechanisms signalling the IDP’s present and future redemption have little to no impact. Analyses employing cognitive and emotional statistical mediators further demonstrate that past behavior shapes justice intuitions because it simultaneously activates a past-oriented moral condemnation and a future-oriented heuristic assessment of the value and risks of associating with the stigmatized individual. This orientation towards past behavior is consistent irrespective of major individual differences including trust in the involved institutions, ISIS victimization, and ethnic identity. These findings highlight the mounting challenges involved in transitional justice in the aftermath of violent conflict and suggests that fact-finding missions are key to re-integration of the millions of displaced persons IDPs currently in Iraq and elsewhere. (Draft paper available upon request).

Baghdad, Al Anbar, and Najaf, Iraq, 2020-2023

Civil conflicts gravely damage the state’s legitimacy. Institutions are rendered incapable of providing security; social trust among its citizenry diminishes; and non-state actors step in to fill the vacuum of power. Following conflict, the state needs to re-establish itself as the legitimate arbiter of processes aimed at bringing former rebel collaborators to justice. Unless it carefully considers subnational variation in the drivers of forgiveness and reconciliation with rebel collaborators, the state may generate new grievances among some communities, increasing the chances of rebel recidivism or the outbreak of new conflict. This project develops and tests a novel framework integrating political science theories of legitimacy with psychological theories of forgiveness, feelings of (in)justice, and desire for revenge. To test this framework, we conduct in-depth interviews, hold focus groups and implement three large-scale surveys with embedded experiments among citizens and local leaders (N=4,800) in Iraq, a country that has endured a series of civil conflicts culminating in the recent confrontation with the Islamic State in Iraq and Syria (ISIS). This project employs innovative tools to identify both the subnational drivers of violent resentment towards the state and the drivers of reconciliation. It provides policymakers with the information necessary to design successful strategies for reconciliation, re-establishment of state legitimacy, and lasting peace. With Michael Bang Petersen and Kristin Fabbe. Funded by Riksbankens Jubileumsfond 3.2 million SEK (approx. 320,000 USD) and the Folke Bernadotte Academy for 396 000 SEK (approx. 42,000 USD) .


December 2021: 6 focus groups on traditional leaders and post-conflict reconciliation with IDPs were conducted in Baghdad, Al Anbar, and Ninewa governorates.

July 2022: ±4,500 surveys completed in Baghdad, Al Anbar, and Ninewa governorates.

September 2022: 400 surveys completed with local leaders in Baghdad, Al Anbar, and Ninewa governorates. 


  • August 2022: “From Revenge to Reconciliation”, Toulouse, France.             

Participants: Michael Bang Petersen (Aarhus University, Denmark) and Kristin Fabbe (Harvard University).

Workshop Outcome Paper:  Kao, Kristen; Fabee, Krisitin, Petersen, Michael Bang. “The Irredeemability of the Past: Determinants of Reconciliation and Revenge in Post-Conflict Settings”. Draft Available upon request. 

  • February 2021: “Understanding and Measuring Punishment, Revenge, and Forgiveness in Post-Conflict Settings,” Virtual.  

Participants: Top scholars from the fields of political science and psychology including Michael McCullough (University of California, San Diego), James Gibson (Washington University), Daniel Posner (University of California, Los Angeles), Everett Worthington (Virginia Commonwealth University), Alexandra Hartman (University College London), Muslih Irwani(Salahaddin University-Erbil, Iraq), Karin Dyrstad (Norwegian University of Science and Technology), Salma Mousa (Yale University), Fotini Christia (Massachusetts Institute of Technology), and Marsin Alshamary (Brookings Institution).

Related Presentations: 

Kao, Kristen (2023). “The Neuroscience of Peace and Conflict“. (presenter). The 2023 United Nations Behavioral Science Week (online). Hosted by the UN Innovation Network, June 14. The webinar was attended by 180 persons. The recording can be found here. 

Kao, Kristen (2022). “Experimental Approaches to Authoritarianism and Violence”. (presenter). Workshop hosted by Prof. Tore Wig and Dr. Sirianne Dahlum,  University of Oslo, October 12-13. 

Kao, Kristen. (2021). “The Limits of Legitimacy: Legal Pluralism in Iraq.” (Presenter and panel co-organizer). APSA 2021, October 2. 

Kao, Kristen (2021). “Conflict, Gender and Political Representation.” (Chair). APSA, October 3. 
Kao, Kristen. (2021). “Islamist Armed Conflicts in the Middle East: between legitimacy and authority.” (Ignite speaker). The Folke Bernadotte Academy Research-Policy Dialogue, October 11.

Kristen Kao.(2020). “From Revenge to Forgiveness: Strengthening Durable Peace in Post-Conflict Societies.” The Folke Bernadotte Academy, Stockholm, Sweden, February 6.

Kristen Kao. (2020). “Retribution or Reconciliation? Post-Conflict Attitudes Toward Enemy Collaborators.” Comparative Politics Working Group, University of California, San Diego, December 2.

Kristen Kao. (2019). “From Revenge to Forgiveness: Strengthening Durable Peace in Post-Conflict Societies.” Middle East Initiative, Harvard Kennedy School, October 31. AFS/General Research Seminar, Gothenburg University. 

Kristen Kao. (2019). “Retribution or Reconciliation? Attitudes Toward Rebel Collaborators in Iraq.” Middle East Initiative, Harvard Kennedy School, December 9. Hosted by Tarek Massoud. 


Gothenburg, Sweden, To Punish or To Pardon, 2020-2022

Thousands of European citizens who travelled to Iraq and Syria to join the Islamic State (IS) now seek repatriation and reintegration into their home communities. This project seeks to understand the conditions under which Europeans will accept the return of compatriot IS collaborators into their communities. How does variation in the social identity of an IS collaborator (e.g. gender, age) or the type of collaboration (e.g. combat, marriage to a fighter, or employment in a civilian job) affect prospects for reintegration? Can state-imposed punishments or rehabilitative measures contribute to reconciliation? Or should these transgressions result in the loss of citizenship for these Europeans, as some policymakers are promoting? Moreover, once the state decides to impose a punishment, how do injustice gaps between what a person perceives as appropriate and what the state decides affect desires for retribution and state legitimacy? 

This project develops a theoretical framework integrating political theories of state legitimacy with psychological theories of (in)justice, retribution, and forgiveness. To test this framework, we will run Facebook surveys in Sweden with embedded conjoint experiments. The study includes a sample of 1500 Swedish-speaking and 1000 Arabic-speaking inhabitants of Sweden in order to allow for examination of variations across older versus newer residents of Europe. In this age of international terrorism, this project provides policymakers with information to help create safe, secure, and inclusive societies, with broader implications for others accused of criminal behaviors and the legitimacy of the state. With Peter Essaiason. Funded by Lundgrens Vetenskapsfond 65,000 SEK (approx. 7,500 USD).

Legal Pluralism and Fragmented Sovereignty: A Survey Experiment in Iraq, 2018-2019

Where state and non-state legal orders coexist within the same territory, what factors determine individual preferences among alternative providers of justice and order? Are some people more prone to favor legal pluralism versus believing in the legitimacy of a single legal system for all cases? Or does it depend on factors that are specific to the case? Systematic, empirical research on this question is lacking, particularly in the Middle East. Through a series of vignette experiments conducted among Sunni Arabs in the Iraqi city of Mosul, where the population has long been exposed to numerous justice systems (state, tribal, and Islamic), this research demonstrates which types of people are most likely to prefer which type of legal systems and provides some insights as to why. The results fill a gap in the extant research by causally identifying factors across dispute cases that drive selection of one type of system over another. Disputes within the family are generally directed towards customary legal orders, though participants prefer that more costly cases go to the state legal system. Sectarian outgroup dynamics are not as impactful as one might expect. Observational data analyses demonstrate that Moslawis face a difficult choice between a highly corrupt, but highly powerful state system and less enforceable, seemingly less corrupt non-state orders. Women and respondents with lower monthly incomes tend to prefer non-state forums.

Six post-survey focus groups reveal that rather than challenging the state, non-state orders play a unique role in local level governance. Customary systems offer citizens a more restorative route for dispute resolution that focuses on the maintenance of social relationships among community members. This may explain why women tend to shun the state system, which is expected by research in other post-conflict contexts to better protect their rights. As the poor may not be able to afford the costs associated with lawyers and state court fees, their preference for customary systems may result from structural inequalities. These findings contribute to ongoing debates over how much prevailing models of peace and state-building should be reformed from championing state-centered approaches to encouraging complementarity between customary forms of dispute resolution and state ones. This research has important implications for efforts by governments and development practitioners seeking to maintain peace and order in areas where state legitimacy and sovereignty are limited.

Related Publications:

Kao, Kristen. “Legal Pluralism and Fragmented Sovereignty: A Survey Experiment in Iraq.” 2022. Quality of Government Institute Working Paper Series, 2022:5. (full paper).

Kao, Kristen; Fabbe, Kristin and Michael Bang Petersen. “The Power of the Past: Determinants of Reconciliation and Revenge in Post-Conflict Settings.” Draft available upon request.

Related Presentations:

ISA 2022, MPSA 2022, and EuroWeps 2022.

Reintegration of Rebel Collaborators: Survey Experiments in Mosul, 2017-2018.

What are the conditions under which civilians will accept neighbors who collaborated with an insurgent group back into their community after conflict? Does punishment of rebel collaborators facilitate post-conflict reintegration? What are the effects of the identity of a rebel collaborator (e.g. gender, age, ethnicity) and the nature of her collaboration with the insurgent group (e.g. marriage to a fighter, military service, or logistical support) on the form of punishment (e.g. imprisonment, reparations, de-radicalization programs, and community service) desired by their community members to promote forgiveness and reconciliation? We address these questions through a conjoint survey experiment conducted in the Iraqi city of Mosul, which was controlled and governed by the Islamic State (IS) for more than three years. We find that people who collaborated to greater extents or are perceived as having done so willingly will be less likely to be accepted back into the community compared to those who collaborated to lesser extents or were coerced to collaborate. The findings of this research have important implications for the stabilization and reconstruction of war-torn societies around the world. The survey was administered in Mosul in March-April 2018 by an experienced and respected Iraqi research firm (N=1,450). The pre-analysis plan for this work here. With Mara Revkin. Our working paper “From Revenge to Forgiveness: Strengthening Durable Peace in Post-Conflict Societies” won the 2019 Franklin L. Burdette Pi Sigma Alpha Award for the best paper presented at the American Political Science Association (APSA) annual meeting and is published in the American Journal of Political Science.

Related Publications:

Kao, Kristen and Revkin, Mara. (2018). “To punish or to pardon?” The Program on Governance and Local Development Working Paper No. 17, University of Gothenburg. (full text)

Kao, Kristen and Revkin, Mara. (2019) “How the Iraqi crackdown on the Islamic State may actually increase support for the Islamic State.” Washington Post/Monkey Cage. (full article)

Kao, Kristen and Revkin, Mara. (2021). “Retribution or Reconciliation? Post-Conflict Attitudes toward Enemy Collaborators.” American Journal of Political Science. (full article)

Kao, Kristen, with Mara Revkin. In Press. “No Peace Without Punishment? Reintegrating Islamic State Collaborators in Iraq.” The American Journal of Comparative Law. (full article)

Kao, Kristen with Mara Revkin. 2021. “Retribution or Reconciliation? Attitudes Towards Rebel Collaborators After Conflict.” American Journal of Political Science. Winner of the Franklin L. Burdette/Pi Sigma Alpha Best Paper Award for APSA 2019. (full article)

Kao, Kristen with Revkin, Mara. (2021). “To Punish or To Pardon: Reintegrating Rebel Collaborators After Conflict in Iraq” Project on Middle East Political Science (POMEPS) Podcast. (full audio)

Revkin, Mara and Kao, Kristen. (2021). How Does Punishment Affect Reintegration? Attitudes Toward Islamic State “Collaborators” in Iraq (2021). Program on Governance and Local Development Working Paper No. 41. (full article).

Related Presentations:

Mara Revkin and Kristen Kao. (2021). “Retribution or Reconciliation? Post-Conflict Attitudes Toward Enemy Collaborators,” International Relations and Methods Workshop, UCLA Department of Political Science, March 8. 

Kao, Kristen. (2021). “Islamist Armed Conflicts, Networks and Negotiations.” (Discussant). Research Workshop on Resolving Islamist Armed Conflicts, The Folke Bernadotte Academy, October 10. 

Kao, Kristen. (2021). “The Limits of Legitimacy: Legal Pluralism in Iraq.” (Panelist). Research Workshop on Resolving Islamist Armed Conflicts, The Folke Bernadotte Academy, October 10. 

Kristen Kao. (2018). Variation in Exposure to Rebel Governance and Preferences for Transitional Justice: Experimental Evidence from Iraq.” Graduate Institute International Relations/Political Science Colloquium Series, The Graduate Institute, Geneva, December 4.