Skip to main content Accessibility help

Public Opinion and the Democratic Peace

  • MICHAEL R. TOMZ (a1) and JESSICA L. P. WEEKS (a2)


One of the most striking findings in political science is the democratic peace: the absence of war between democracies. Some authors attempt to explain this phenomenon by highlighting the role of public opinion. They observe that democratic leaders are beholden to voters and argue that voters oppose war because of its human and financial costs. This logic predicts that democracies should behave peacefully in general, but history shows that democracies avoid war primarily in their relations with other democracies. In this article we investigate not whether democratic publics are averse to war in general, but whether they are especially reluctant to fight other democracies. We embedded experiments in public opinion polls in the United States and the United Kingdom and found that individuals are substantially less supportive of military strikes against democracies than against otherwise identical autocracies. Moreover, our experiments suggest that shared democracy pacifies the public primarily by changing perceptions of threat and morality, not by raising expectations of costs or failure. These findings shed light on a debate of enduring importance to scholars and policy makers.


Corresponding author

Michael R. Tomz is Professor of Political Science, Stanford University (
Jessica L. P. Weeks is Assistant Professor of Political Science, University of Wisconsin–Madison (


Hide All
Aldrich, John H., Sullivan, John L., and Borgida, Eugene. 1989. “Foreign Affairs and Issue Voting.” American Political Science Review 83 (1): 123–41.
Almond, Gabriel A. 1960. The American People and Foreign Policy. New York: Praeger.
Baum, Matthew A. 2004. “How Public Opinion Constrains the Use of Force: The Case of Operation Restore Hope.” Presidential Studies Quarterly 34 (2): 187226.
Baum, Matthew A., and Groeling, Tim. 2009. “Shot by the Messenger: Partisan Cues and Public Opinion Regarding National Security and War.” Political Behavior 31 (2): 157–86.
Baum, Matthew A., and Potter, Philip B. K.. 2008. “The Relationships between Mass Media, Public Opinion, and Foreign Policy: Toward a Theoretical Synthesis.” Annual Review of Political Science 11: 3965.
Berinsky, Adam J. 2007. “Assuming the Costs of War: Events, Elites, and American Public Support for Military Conflict.” Journal of Politics 69 (4): 975–97.
Berinsky, Adam J. 2009. In Time of War. Chicago: University of Chicago Press.
Berinsky, Adam J., Huber, Gregory A., and Lenz, Gabriel S.. 2012. “Evaluating Online Labor Markets for Experimental Research: Amazon's Mechanical Turk.” Political Analysis 20: 351–68.
Bueno de Mesquita, Bruce, Morrow, James D., Siverson, Randolph M., and Smith, Alastair. 1999. “An Institutional Explanation of the Democratic Peace.” American Political Science Review 93 (4): 791807.
Canes-Wrone, Brandice. 2006. Who Leads Whom? Presidents, Policy, and the Public. Chicago: University of Chicago Press.
Dafoe, Allan. 2011. “Statistical Critiques of the Democratic Peace: Caveat Emptor.” American Journal of Political Science 55 (2): 247–62.
Debs, Alexandre, and Goemans, H. E.. 2010. “Regime Type, the Fate of Leaders, and War.” American Political Science Review 104 (3): 430–45.
Dixon, William J. 1994. “Democracy and the Peaceful Settlement of International Conflict.” American Political Science Review 88 (1): 1432.
Doyle, Michael W. 1983. “Kant, Liberal Legacies, and Foreign Affairs.” Philosophy & Public Affairs 12 (3): 205–35.
Doyle, Michael W. 1986. “Liberalism and World Politics.” American Political Science Review 80 (4): 1151–69.
Edwards, George. 1997. “Aligning Tests with Theory: Presidential Approval as a Source of Influence in Congress.” Congress and the Presidency 24 (2): 113–30.
Farber, Henry S., and Gowa, Joanne. 1995. “Polities and Peace.” International Security 20 (2): 123–46.
Fearon, James D. 1994. “Domestic Political Audiences and the Escalation of International Disputes.” American Political Science Review 88 (3): 577–92.
Fearon, James D. 1995. “Rationalist Explanations for War.” International Organization 49 (3): 379414.
Finnemore, Martha. 2003. The Purpose of Intervention. Ithaca, NY: Cornell University Press.
Foyle, Douglas C. 1999. Counting the Public In: Presidents, Public Opinion, and Foreign Policy. New York: Columbia University Press.
Gartner, Scott Sigmund. 2008. “The Multiple Effects of Casualties on Public Support for War: An Experimental Approach.” American Political Science Review 102 (1): 95106.
Gartzke, Erik. 1998. “Kant We All Just Get Along? Opportunity, Willingness, and the Origins of the Democratic Peace.” American Journal of Political Science 42 (1): 127.
Gartzke, Erik. 2007. “The Capitalist Peace.” American Journal of Political Science 51 (1): 166–91.
Gelpi, Christopher, Feaver, Peter D., and Reifler, Jason. 2006. “Success Matters: Casualty Sensitivity and the War in Iraq.” International Security 30 (3): 746.
Gelpi, Christopher, Feaver, Peter, and Reifler, Jason A.. 2009. Paying the Human Costs of War: American Public Opinion and Casualties in Military Conflicts. Princeton, NJ: Princeton University Press.
Gelpi, Christopher, Reifler, Jason, and Feaver, Peter. 2007. “Iraq the Vote: Retrospective and Prospective Foreign Policy Judgments on Candidate Choice and Casualty Tolerance.” Political Behavior 29 (2): 151–74.
Geva, Nehemia, DeRouen, Karl R., and Mintz, Alex. 1993. “The Political Incentive Explanation of ‘Democratic Peace’: Evidence from Experimental Research.” International Interactions 18 (3): 215–29.
Geva, Nehemia, and Hanson, D. Christopher. 1999. “Cultural Similarity, Foreign Policy Actions, and Regime Perception: An Experimental Study of International Cues and Democratic Peace.” Political Psychology 20 (4): 803–27.
Ghosn, Faten, Palmer, Glenn, and Bremer, Stuart A.. 2004. “The MID3 Data Set, 1993–2001: Procedures, Coding Rules, and Description.” Conflict Management and Peace Science 21 (2): 133–54.
Gibler, Douglas M. 2007. “Bordering on Peace: Democracy, Territorial Issues, and Conflict.” International Studies Quarterly 51 (3): 509–32.
Gowa, Joanne S. 1999. Ballots and Bullets: The Elusive Democratic Peace. Princeton, NJ: Princeton University Press.
Grieco, Joseph M., Gelpi, Christopher, Reifler, Jason, and Feaver, Peter D.. 2011. “Let's Get a Second Opinion: International Institutions and American Public Support for War.” International Studies Quarterly 55 (2): 563–83.
Gronke, Paul, Koch, Jeffrey, and Wilson, J. Matthew. 2003. “Follow the Leader? Presidential Approval, Presidential Support, and Representatives’ Electoral Fortunes.” Journal of Politics 65 (3): 785808.
Hafner-Burton, Emilie M., Hughes, Alex, and Victor, David G.. 2013. “The Cognitive Revolution and the Political Psychology of Elite Decision Making.” Perspectives on Politics 11 (2): 368–86.
Hartley, Thomas, and Russett, Bruce. 1992. “Public Opinion and the Common Defense: Who Governs Military Spending in the United States?American Political Science Review 86 (4): 905–15.
Harrison, Ewan. 2004. “State Socialization, International Norm Dynamics and the Liberal Peace.” International Politics 41 (4): 521–42.
Hermann, Margaret G., and Kegley, Charles W.. 1995. “Rethinking Democracy and International Peace: Perspectives from Political Psychology.” International Studies Quarterly 39 (4): 511–33.
Herrmann, Richard K., and Shannon, Vaughn P.. 2001. “Defending International Norms: The Role of Obligation, Material Interest, and Perception in Decision Making.” International Organization 55 (3): 621–54.
Herrmann, Richard K., Tetlock, Philip E., and Visser, Penny S.. 1999. “Mass Public Decisions to Go to War: A Cognitive-Interactionist Framework.” American Political Science Review 93 (3): 553–73.
Herrmann, Richard K., Voss, James F., Schooler, Tonya Y. E., and Chiarrochi, Joseph. 1997. “Images in International Relations: An Experimental Test of Cognitive Schemata.” International Studies Quarterly 41 (3): 403–33.
Herron, Kerry G., and Jenkins-Smith, Hank C.. 2002. “U.S. Perceptions of Nuclear Security in the Wake of the Cold War: Comparing Public and Elite Belief Systems.” International Studies Quarterly 46 (4): 451–79.
Hildebrandt, Timothy, Hillebrecht, Courtney, Holm, Peter M., and Pevehouse, Jon. 2013. “The Domestic Politics of Humanitarian Intervention: Public Opinion, Partisanship, and Ideology.” Foreign Policy Analysis 9 (3): 243–66.
Holsti, Ole R. 2004. Public Opinion and American Foreign Policy. rev. ed. Ann Arbor: University of Michigan Press.
Holyk, Gregory G. 2011. “Individual-level Predictors of Leader and Public Support for the Use of Force.” International Journal of Public Opinion Research 23 (2): 214–29.
Horowitz, Michael C., and Levendusky, Matthew S.. 2011. “Drafting Support for War: Conscription and Mass Support for Warfare.” Journal of Politics 73 (2): 524–34.
Howell, William G., and Pevehouse, Jon C.. 2007. While Dangers Gather: Congressional Checks on Presidential War Powers. Princeton, NJ: Princeton University Press.
Imai, Kosuke, Keele, Luke, Tingley, Dustin, and Yamamoto, Teppei. 2011. “Unpacking the Black Box of Causality: Learning about Causal Mechanisms from Experimental and Observational Studies.” American Political Science Review 105 (4): 765–89.
Imai, Kosuke, Keele, Luke, and Yamamoto, Teppei. 2010. “Identification, Inference, and Sensitivity Analysis for Causal Mediation Effects.” Statistical Science 25 (1): 5171.
Jervis, Robert. 1976. Perception and Misperception in International Politics. Princeton, NJ: Princeton University Press.
Jervis, Robert. 1978. “Cooperation under the Security Dilemma.” World Politics 30 (2):167214.
Johns, Robert, and Davies, Graeme. 2012. “Democratic Peace or Clash of Civilizations? Target States and Support for War in Britain and the United States.” Journal of Politics 74 (4): 1038–52.
Jones, Byron, and Kenward, Michael G.. 2003. Design and Analysis of Cross-over Trials. 2nd ed. New York: Chapman & Hall.
Kahl, Colin H. 1998. “Constructing a Separate Peace: Constructivism, Collective Liberal Identity, and Democratic Peace.” Security Studies 8 (2–3): 94144.
Kant, Immanuel. [1795] 1991. Kant's Political Writings. Edited by Hans Reiss. 2nd ed. Cambridge: Cambridge University Press.
Krosnick, Jon A., and Kinder, Donald R.. 1990. “Altering the Foundations of Support for the President through Priming.” American Political Science Review 84 (2): 497512.
Kydd, Andrew H. 2005. Trust and Mistrust in International Relations. Princeton, NJ: Princeton University Press.
Lacina, Bethany, and Lee, Charlotte. 2012. “Culture Clash or Democratic Peace?: Results of a Survey Experiment on the Effect of Religious Culture and Regime Type on Foreign Policy Opinion Formation.” Foreign Policy Analysis 9 (2): 143–70.
Lake, David A. 1992. “Powerful Pacifists: Democratic States and War.” American Political Science Review 86 (1): 2437.
Lektzian, David, and Souva, Mark. 2009. “A Comparative Theory Test of Democratic Peace Arguments, 1946–2000.” Journal of Peace Research 46 (1): 1737.
Levendusky, Matthew S., and Horowitz, Michael C.. 2012. “When Backing Down Is the Right Decision: Partisanship, New Information, and Audience Costs.” Journal of Politics 74 (2): 323–38.
Levy, Jack S. 1988. “Domestic Politics and War.” Journal of Interdisciplinary History 18 (4): 653–73.
Lindsay, James M. 1994. Congress and the Politics of U.S. Foreign Policy. Baltimore: Johns Hopkins University Press.
Maoz, Zeev, and Russett, Bruce. 1993. “Normative and Structural Causes of Democratic Peace, 1946–1986.” American Political Science Review 87 (3): 624–38.
McDermott, Rose. 2011. “New Directions for Experimental Work in International Relations.” International Studies Quarterly 55 (2): 503–20.
McDonald, Patrick J. 2009. The Invisible Hand of Peace: Capitalism, the War Machine, and International Relations Theory. New York: Cambridge University Press.
Mearsheimer, John J. 2003. The Tragedy of Great Power Politics. New York: W. W. Norton.
Mintz, Alex, and Geva, Nehemia. 1993. “Why Don't Democracies Fight Each Other? An Experimental Study.” Journal of Conflict Resolution 37 (3): 484503.
Morgan, T. Clifton, and Campbell, Sally Howard. 1991. “Domestic Structure, Decisional Constraints, and War.” Journal of Conflict Resolution 35 (2): 187211.
Morgenthau, Hans J. 1948. Politics among Nations. New York: Knopf.
Mueller, John E. 1973. War, Presidents, and Public Opinion. New York: Wiley.
Narizny, Kevin. 2003. “Both Guns and Butter, or Neither: Class Interests in the Political Economy of Rearmament.” American Political Science Review 97 (2): 203–20.
Oneal, John R., and Russett, Bruce M.. 1999. “Is the Liberal Peace Just an Artifact of Cold War Interests? Assessing Recent Critiques.” International Interactions 25 (3): 213–41.
Owen, John M. 1994. “How Liberalism Produces Democratic Peace.” International Security 19 (2): 87125.
Owen, John M. 1997. Liberal Peace, Liberal War: American Politics and International Security. Ithaca, NY: Cornell University Press.
Press, Daryl G., Sagan, Scott D., and Valentino, Benjamin A.. 2013. “Atomic Aversion: Experimental Evidence on Taboos, Traditions, and the Non-use of Nuclear Weapons.” American Political Science Review 107 (1): 188206.
Price, Richard. 1998. “Reversing the Gun Sights: Transnational Civil Society Targets Land Mines.” International Organization 52 (3): 613–44.
Dan, Reiter, and Stam, Allan C.. 2002. Democracies at War. Princeton, NJ: Princeton University Press.
Risse-Kappen, Thomas. 1995. “Democratic Peace—Warlike Democracies?European Journal of International Relations 1 (4): 491517.
Rosato, Sebastian. 2003. “The Flawed Logic of Democratic Peace Theory.” American Political Science Review 97 (4): 585602.
Rosenau, James N. 1961. Public Opinion and Foreign Policy: An Operational Formulation. New York: Random House.
Rousseau, David L. 2005. Democracy and War: Institutions, Norms, and the Evolution of International Conflict. Stanford, CA: Stanford University Press.
Rummel, R. J. 1979. War, Power, Peace. Vol. 4 of Understanding Conflict and War. Beverly Hills, CA: Sage.
Russett, Bruce M. 1990. Controlling the Sword: The Democratic Governance of National Security. Cambridge, MA: Harvard University Press.
Russett, Bruce M. 1993. Grasping the Democratic Peace: Principles for a Post-Cold War World. Princeton, NJ: Princeton University Press.
Russett, Bruce M. 2010. “Capitalism or Democracy? Not So Fast.” International Interactions 36 (2): 198205.
Russett, Bruce M., and Oneal, John R.. 2001. Triangulating Peace: Democracy, Interdependence, and International Organizations. New York: W. W. Norton.
Schultz, Kenneth. 1999. “Do Democratic Institutions Constrain or Inform?International Organization 53 (2): 233–66.
Schultz, Kenneth A. 2001. Democracy and Coercive Diplomacy. New York: Cambridge University Press.
Slantchev, Branislav. 2005. “Military Coercion in Interstate Crises.” American Political Science Review 99 (4): 533–47.
Slantchev, Branislav. 2011. Military Threats: The Costs of Coercion and the Price of Peace. New York: Cambridge University Press.
Sobel, Richard. 2001. The Impact of Public Opinion on U.S. Foreign Policy since Vietnam: Constraining the Colossus. New York: Oxford University Press.
Thucydides. 1954. History of the Peloponnesian War. Transl. Warner, Rex. New York: Penguin.
Tingley, Dustin. 2011. “The Dark Side of the Future: An Experimental Test of Commitment Problems in Bargaining.” International Studies Quarterly 55 (2): 521–44.
Tingley, Dustin, and Walter, Barbara F.. 2011. “The Effect of Repeated Play on Reputation Building: An Experimental Approach.” International Organization 65 (2): 343–65.
Tomz, Michael. 2007. “Domestic Audience Costs in International Relations: An Experimental Approach.” International Organization 61 (4): 821–40.
Trager, Robert F., and Vavreck, Lynn. 2011. “The Political Costs of Crisis Bargaining: Presidential Rhetoric and the Role of Party.” American Journal of Political Science 55 (3): 526–45.
Verba, Sidney, Schlozman, Kay Lehman, Brady, Henry, and Nie, Norman H.. 1993. “Citizen Activity: Who Participates? What Do They Say?American Political Science Review 87 (2): 303–18.
Welch, David A. 1993. Justice and the Genesis of War. New York: Cambridge University Press.
Wendt, Alexander. 1999. Social Theory of International Politics. Cambridge: Cambridge University Press.
Wildavsky, Aaron. 1966. “The Two Presidencies.” Society 4 (2): 714.
Williams, Michael C. 2001. “The Discipline of the Democratic Peace.” European Journal of International Relations 7 (4): 525–53.
Wittkopf, Eugene R. 1987. “Elites and Masses: Another Look at Attitudes toward America's World Role.” International Studies Quarterly 31 (2): 131–59.
Wittkopf, Eugene R., and Maggiotto, Michael A.. 1983. “Elites and Masses: A Comparative Analysis of Attitudes toward America's World Role.” Journal of Politics 45 (2): 303–34.

Related content

Powered by UNSILO

Public Opinion and the Democratic Peace

  • MICHAEL R. TOMZ (a1) and JESSICA L. P. WEEKS (a2)


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.