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How Democratic Alliances Solve the Power Parity Problem

  • Justin Conrad


Why do challengers attack some states that have allies, while avoiding conflict with others? This article builds upon previous research by arguing that parity in the observable capabilities of opposing states and their allies generates greater uncertainty and miscalculations on the part of challengers, which leads to a higher probability of conflict. Unlike previous research, however, this article argues that military alliances among democracies are better able to overcome this uncertainty, making power distributions largely irrelevant. The results demonstrate that uncertainty generated at power parity is mitigated when a target state’s allies are more democratic, resulting in no overall change in the probability of conflict. This study therefore emphasizes that the effectiveness of military alliances lies not necessarily in their aggregation of power, but in their ability to co-ordinate their power and communicate this co-ordination to potential challengers.



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University of North Carolina at Charlotte, Department of Political Science and Public Administration, 450B Fretwell Bldg., 9201 University City Blvd., Charlotte, North Carolina 28202 (email: I would like to thank Mark Souva, David Siegel, William Reed, Robert Art and Will Moore for their guidance and helpful suggestions on this project. Data replication sets are available at, and online appendices are available at



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Alvarez, R. Michael, and Brehm, John. 1995. American Ambivalence Towards Abortion Policy: Development of a Heteroskedastic Probit Model of Competing Values. American Journal of Political Science 39:10551082.
Barnett, Michael N., and Levy, Jack S.. 1991. Domestic Sources of Alliances and Alignments: The Case of Egypt, 1962–1973. International Organization 45:369395.
Bearce, David H., Flanagan, Kristen M., and Floros, Katharine M.. 2006. Alliances, Internal Information, and Military Conflict Among Member-States. International Organization 60 (3):595625.
Bennett, D. Scott. 1997. Testing Alternative Models of Alliance Duration, 1816–1984. American Journal of Political Science 41 (3):846878.
Bennett, D. Scott, and Stam, Allan C.. 2000. A Universal Test of an Expected Utility Theory of War. International Studies Quarterly 44 (3):451480.
Blainey, Geoffrey. 1988. The Causes of War. New York: Simon and Schuster.
Braumoeller, Bear F. 2006. Explaining Variance; or, Stuck in a Moment We Can’t Get Out Of. Political Analysis 14 (3):268290.
Bremer, Stuart A. 1992. Dangerous Dyads: Conditions Affecting the Likelihood of Interstate War, 1816–1965. Journal of Conflict Resolution 36:309341.
Bueno de Mesquita, Bruce. 1975. Measuring Systemic Polarity. Journal of Conflict Resolution 19 (2):187216.
Bueno de Mesquita, Bruce, and Lalman, David. 1992. War and Reason. New Haven, CT: Yale University Press.
Bueno de Mesquita, Bruce, and Downs, George W.. 2006. Intervention and Democracy. International Organization 60 (3):627649.
Bueno de Mesquita, Bruce, Morrow, James D., and Zorick, Ethan R.. 1997. Capabilities, Perception, and Escalation. American Political Science Review 93 (4):1527.
Bueno de Mesquita, Bruce, Morrow, James D., Siverson, Ralph M., and Smith, Alastair. 1999. An Institutional Explanation of the Democratic Peace. The American Political Science Review 93 (4):791807.
Bueno de Mesquita, Bruce, Smith, Alastair, Siverson, Ralph M., and Morrow, James D.. 2005. The Logic of Political Survival. Cambridge, MA: MIT Press.
Carter, David B., and Signorino, Curtis S.. 2010. Back to the Future: Modeling Time Dependence in Binary Data. Political Analysis 18:271292.
Choi, Ajin. 2003. The Power of Democratic Cooperation. International Security 28 (1):142153.
Christensen, Thomas J., and Snyder, Jack. 1990. Chain Gangs and Passed Bucks: Predicting Alliance Patterns in Multipolarity. International Organization 44 (2):137168.
Cowhey, Peter. F. 1993. Domestic Institutions and the Credibility of International Commitments. International Organization 47:299326.
DiCicco, Jonathan, and Levy, Jack. 1999. Power Shifts and Problem Shifts. Journal of Conflict Resolution 43:269284.
Downs, George, and Rocke, David. 1979. Interpreting Heteroscedasticity. American Journal of Political Science 23:816828.
Fearon, James D. 1992. Threats to Use Force: Costly Signals and Bargaining in International Crises. Ph.D. dissertation, University of California, Berkeley.
Fearon, James D. 1994. Domestic Political Audiences and the Escalation of International Disputes. American Political Science Review 88:577592.
Fearon, James D. 1995. Rationalist Explanations for War. International Organization 49 (3):379414.
Fearon, James D. 1997. Signaling Foreign Policy Interests: Tying Hands Versus Sinking Costs. Journal of Conflict Resolution 41 (1):6890.
Gartzke, Eric, and Gleditsch, Kristian Skrede. 2004. Why Democracies May Actually Be Less Reliable Allies. American Journal of Political Science 48 (4):775795.
Gaubatz, Kurt Taylor. 1996. Democratic States and Commitment in International Relations. International Organization 50:109130.
Geller, Daniel S. 1993. Power Differentials and War in Rival Dyads. International Studies Quarterly 37 (2):173193.
Gelpi, Christopher, and Grieco, Joseph. 2001. Democracy, Leadership Tenure, and the Targeting of Militarized Challenges. Journal of Conflict Resolution 45 (6):794817.
Gibler, Douglas M., and Vasquez, John A.. 1998. Uncovering the Dangerous Alliances, 1495–1980. International Studies Quarterly 42 (4):785807.
Gochman, Charles. 1990. Capability-Driven Disputes. In Prisoners of War?, edited by Gochman and Sabrosky, 141159. Lexington, MA: Lexington Books.
Hoff, Peter D., and Ward, Michael D.. 2004. Modeling Dependencies in International Relations Networks. Political Analysis 12:160175.
Huth, Paul K. 1996. Standing Your Ground: Territorial Disputes and International Conflict. Ann Arbor: University of Michigan Press.
Huth, Paul K., and Allee, Todd L.. 2002. Domestic Political Accountability and the Escalation and Settlement of International Disputes. The Journal of Conflict Resolution 46 (6):754790.
Jervis, Robert. 1976. Perception and Misperception in International Politics, Vol. 49. Princeton, NJ: Princeton University Press.
Jones, Bryan D. 1999. Bounded Rationality. Annual Review of Political Science 2 (1):297321.
Jones, Daniel M., Bremer, Stuart A., and David Singer, J.. 1996. Militarized Interstate Disputes, 1816–1992: Rationale, Coding Rules, and Empirical Patterns. Conflict Management and Peace Science 15 (2):163213.
Kahneman, Daniel, and Tversky, Amos. 1979. Prospect Theory: An Analysis of Decision Under Risk. Econometrica 47:263291.
Kahneman, Daniel, and Tversky, Amos. 1984. Choices, Values and Frames. American Psychology 39:341350.
Keele, Luke, and Park, David K.. 2004. Difficult Choices: An Evaluation of Heterogenous Choice Models. Paper Presented at the 2004 Meeting of the American Political Science Association, Chicago, IL, 2–5 September.
Kegley, Charles. W., Jr., and Raymond, Gregory. A.. 1994. A Multipolar Peace? Great-Power Politics in the Twenty-First Century. New York: St. Martin’s Press.
Kim, Woosang. 1989. Power, Alliance, and Major Wars, 1816–1975. Journal of Conflict Resolution 33:255273.
Kim, Woosang. 1991. Alliance Transitions and Great Power War. American Journal of Political Science 35:833850.
Kim, Woosang. 2003. Power Parity, Alliance, Dissatisfaction, and Wars in East Asia, 1860–1993. Journal of Conflict Resolution 46 (5):654671.
Kugler, Jacek, and Organski, Abramo. F. K.. 1980. The War Ledger. Chicago, IL: University of Chicago Press.
Lebow, Richard Ned. 1981. Between Peace and War: The Nature of International Crisis. Baltimore, MD: Johns Hopkins University Press.
Leeds, Brett Ashley. 1999. Domestic Political Institutions, Credible Commitments, and International Cooperation. American Journal of Political Science 43:9791002.
Leeds, Brett Ashley. 2003a. Do Alliances Deter Aggression? The Influence of Military Alliances on the Initiation of Militarized Interstate Disputes. American Journal of Political Science 47 (3):427439.
Leeds, Brett Ashley. 2003b. Alliance Reliability in Times of War: Explaining State Decisions to Violate Treaties. International Organization 57 (4):801827.
Leeds, Brett Ashley. 2005a. Alliances and the Expansion and Escalation of Militarized Interstate Disputes. In New Directions for International Relations, edited by Alex Mintz and Bruce Russett, 117134. Lanham, MD: Lexington Books.
Leeds, Brett Ashley. 2005b. The Alliance Treaty Obligations and Provisions Project. Available from, accessed 12 December 2011.
Leeds, Brett Ashley, and Savun, Burcu. 2007. Terminating Alliances: Why Do States Abrogate Agreements? Journal of Politics 69 (4):11181132.
Leeds, Brett Ashley, Mattes, Michaela, and Vogel, Jeremy S.. 2009. Interests, Institutions and the Reliability of International Commitments. American Journal of Political Science 53 (2):461476.
Lemke, Doug, and Werner, Suzanne. 1996. Power Parity, Commitment to Change and War. International Studies Quarterly 40:235260.
Levy, Jack S. 1981. Alliance Formation and War Behavior: An Analysis of the Great Powers, 1495–1975. Journal of Conflict Resolution 25 (4):581613.
Mansfield, Edward, Milner, Helen, and Rosendorff, Peter. 2002. Why Democracies Cooperate More: Electoral Control and International Trade Agreements. International Organization 56 (3):477513.
Marshall, Monty, Jaggers, Keith, and Gurr, Ted. 2006. Polity IV Project: Political Regime Characteristics and Transitions, 1800–2004. Available from, accessed 1 May 2009.
Martin, Lisa L. 2000. Democratic Commitments: Legislatures and International Cooperation. Princeton, NJ: Princeton University Press.
Moore, Will H., and Tarar, Ahmer. 2010. Domestic-International Conflict Linkages. In The International Studies Encyclopedia, edited by Robert A. Denemark. Oxford: Blackwell Publishing, Blackwell Reference Online. Available at:
Morgenthau, Hans J. 1967. Politics Among Nations, 4th Edition. New York: Alfred A. Knopf.
Morrow, James D. 1991. Alliances and Asymmetry: An Alternative to the Capability Aggregation Model of Alliances. American Journal of Political Science 35 (4):904933.
Morrow, James D. 1994. Alliances, Credibility, and Peacetime Costs. Journal of Conflict Resolution 38 (2):270297.
Morrow, James D. 1999. The Strategic Setting of Choices: Signaling, Commitment, and Negotiation in International Politics. In Strategic Choice and International Relations, edited by David A. Lake and Robert Powell, 77114. Princeton, NJ: Princeton University Press.
Morrow, James D. 2000. Alliances: Why Write Them Down? American Review of Political Science 3:6383.
Muller, Harald. 2004. Arguing, Bargaining and All That: Communicative Action, Rationalist Theory and the Logic of Appropriateness in International Relations. European Journal of International Relations 10 (3):395435.
Niou, Emerson M. S., and Ordeshook, Peter C.. 1994. ‘Less Filling, Tastes Great’: The Realist-Neoliberal Debate. World Politics 46 (2):209234.
Organski, Abramo F. 1968. World Politics, 2nd Edition. New York: Knopf.
Powell, Robert. 2006. War as a Commitment Problem. International Organization 60 (1):169203.
Reed, William. 2003. Information, Power, and War. American Political Science Review 97 (4):633641.
Rubinstein, Ariel. 1998. Modeling Bounded Rationality, Vol. 1. Cambridge, MA: MIT Press.
Schelling, Thomas. 1960. The Strategy of Conflict. Cambridge, MA: Harvard University Press.
Schelling, Thomas. 1966. Arms and Influence. New Haven, CT: Yale University Press.
Schultz, Kenneth. 1998. Domestic Opposition and Signaling in International Crises. American Political Science Review 92 (4):829844.
Schultz, Kenneth. 1999. Do Democratic Institutions Constrain or Inform? Contrasting Two Institutional Perspectives on Democracy and War. International Organization 53 (2):233266.
Siegel, Eric. 1997. I Know that You Know, and You Know that I Know: An Information Theory of the Democratic Peace. Paper Presented at the 93rd Annual Meeting of the American Political Science Association, Washington, DC, 28 August to 1 September.
Signorino, Curtis S. 2003. Structure and Uncertainty in Discrete Choice Models. Political Analysis 11:316344.
Signorino, Curtis S., and Ritter, Jeffrey M.. 1999. Tau-b or Not Tau-b: Measuring the Similarity of Foreign Policy Positions. International Studies Quarterly 43 (1):115144.
Simon, Herbert. 1976. Administrative Behaviour. New York: Free Press.
Simon, Herbert. 1983. Reason in Human Affairs. Stanford: Stanford University Press.
Simmons, Beth. 2009. Mobilizing for Human Rights: International Law in Domestic Politics. Cambridge, MA: Cambridge University Press.
Singer, David, Bremer, Stuart, and Stuckey, John. 1972. Capability Distribution, Uncertainty, and Major Power War 1820–1965. In Peace, War and Numbers , edited by Bruce Russett, 1948. Beverly Hills: Sage.
Singer, J. David, and Small, Melvin. 1966. National Alliance Commitments and War Involvement, 1815–1945. Journal of Peace Research 5:109140.
Singer, J. David, and Small, Melvin. 1968. Alliance Aggregation and the Onset of War, 1815–1945. Pp. 247–86. in International Politics: Insights and Evidence, edited by J. David Singer. New York: Free Press.
Siverson, Randolph M., and Starr, Harvey. 1991. The Diffusion of War. Ann Arbor: The University of Michigan Press.
Smith, Alastair. 1995. Alliance Formation and War. International Studies Quarterly 39:405425.
Smith, Alastair. 1998. Extended Deterrence and Alliance Formation. International Interactions 24 (4):315343.
Snyder, Glenn H. 1997. Alliance Politics. Ithaca, NY: Cornell University Press.
Stinnett, Douglas M., Tir, Jaroslav, Schafer, Philip, Diehl, Paul F., and Gochman, Charles. 2002. The Correlates of War Project Direct Contiguity Data, Version 3. Conflict Management and Peace Science 19 (2):5866.
Szmer, John, and Songer, Donald R.. 2005. The Effects of Information on the Accuracy of Presidential Assessments of Supreme Court Nominee Preferences. Political Research Quarterly 58 (1):151160.
Tammen, Ronald, Kugler, Jacek, Lemke, Douglas, Alsharabati, Carole, Efird, Brian, and Organski, Abramo. F. K.. 2000. Power Transitions: Strategies for the Twenty-First Century. New York: Chatham House.
Tarar, Ahmer. 2001. International Bargaining with Two-Sided Domestic Constraints. Journal of Conflict Resolution 45 (3):320340.
Waltz, Kenneth N. 1979. Theory of International Politics. New York: Random House.
Wayman, Frank Whelon. 1984. Bipolarity and War: The Role of Capability Concentration and Alliance Patterns Among Major Powers, 1816–1965. Journal of Peace Research 21 (1):6178.
Weede, Erich. 1976. Overwhelming Preponderance as a Pacifying Condition Among Contiguous Asian Dyads, 1950–1969. Journal of Conflict Resolution 20 (3):395411.
Weeks, Jessica L. 2008. Autocratic Audience Costs: Regime Type and Signaling Resolve. International Organization 62 (1):3564.
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How Democratic Alliances Solve the Power Parity Problem

  • Justin Conrad


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