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Jack Levy
Jack Levy
Board of Governors Professor
Hickman Hall - 304

By Appointment

International Relations, Causes of War, Foreign Policy Analysis, Political Psychology, Qualitative Methodology



Professor Levy is Board of Governors’ Professor at Rutgers University and an Affiliate of the Saltzman Institute of War and Peace Studies at Columbia University. He received a B.S. in Physics from Harvey Mudd College and a Ph.D. in Political Science from the University of Wisconsin-Madison. He held tenured positions at the University of Texas at Austin and the University of Minnesota before coming to Rutgers in 1989. He has also held visiting or adjunct positions at Tulane, Stanford, Harvard, Yale, NYU, Aoyama Gakuin, and Columbia University. Levy received APSA's Helen Dwight Reid Award for the best dissertation in International Relations in 1975-76, and the Distinguished Scholar Award from the Foreign Policy Analysis Section of the International Studies Association (2000). He is a past president of the International Studies Association (2007-08) and of the Peace Science Society International (2005-06). Levy was listed (PS, 2007) among the top twenty most widely cited international relations scholars.

Levy’s teaching and research interests are in the field of International Relations, with a special emphasis on the causes of interstate war, foreign policy decision-making, and qualitative methodology. His books include War in the Modern Great Power System, 1495-1975 (1983), Explaining War and Peace: Case Studies and Necessary Condition Counterfactuals (co-edited with Gary Goertz, 2007), Causes of War (with William R. Thompson, 2010), The Arc of War: Origins, Escalation, and Transformation (with William R. Thompson, 2011), The Oxford Handbook of Political Psychology, 2nd ed. (edited with Leonie Huddy and David O. Sears, 2013), and The Outbreak of the First World War: Structure, Politics, and Decision-Making (edited with John A. Vasquez). He has published over 100 articles and chapters in leading journals and in edited volumes.

Levy’s Google Scholar page:


See Bio and CV.


My research focuses primarily on the causes of interstate war, foreign policy decision-making, political psychology, and qualitative methodology. Below I summarize my current research agenda and place it in the context of my earlier work. I organize my scholarly work into the following categories: historical evolution of war; dynamics of power relationships, including balance of power theory, preventive war, and power transition theory; domestic politics and war, including diversionary theory and audience costs; the political economy of war and peace; the psychology of decision-making; qualitative methodology and the philosophy of science/history; the First World War; grand strategy in the 1930s; and my Handbook of Great Power Wars project. Please see my C.V. ( for a more complete list of my publications and work in progress, and for the names of all coauthors.

Historical Evolution of War

My work on the historical evolution of war began with my 1983 book, War in the Modern Great Power System, 1495-1975. The book detailed the generation of a new data base on great power warfare over the last five centuries of warfare, and included as a central theme the question of how to explain the declining frequency but rising severity of great power warfare. This was also a central them in The Arc of War: Origins, Evolution, Transformation (Chicago, 2011), in which William R. Thompson and I significantly extended the temporal domain of the analysis back eight millennia. We developed a new theoretical explanation that is centered around the coevolution of war, political economy, military and political organization, and weaponry from early tribal systems to the contemporary period. More recently, I have engaged in debates with Steven Pinker, Joshua Goldstein, and others on the decline of war and how to explain it.

Dynamics of Power Relationships

My ongoing research projects on balance of power theory, preventive war, and power transition theory grow out of my long-standing interest in the dynamics of power in international relations. Thompson and I are working on a book on the balance of power that builds on my earlier reconceptualization of balance of power theory (2003) and on our joint empirical studies of balancing against hegemonic threats in both the European and global systems during the past five centuries (2005, 2010). We find that great powers have generally tended to balance against hegemonic threats in the European system (but not against lesser threats from a weaker leading power), but they rarely balance against dominant powers in the global system.

I am continuing my long standing research program on preventive war, which has attempted to clarify the meaning of the concept, specify the conditions under which states are most likely to adopt a strategy of preventive war, and question the hypothesis that democracies do not fight preventive wars (1987, 2001, 2011). I have also examined the role of preventive logic in several historical cases – including Israel in the 1956 Sinai Campaign (2001), Germany in the First World War (2014), and Japan in the Russo-Japanese War (2015). With Norrin Ripsman, I have also examined a case in which a preventively-motivated war did not occur despite theoretically optimal conditions – the 1930s (2007). A current project focuses on a theoretical and empirical puzzle in the theory of preventive war. If declining states are often led by better-now-than-later logic to adopt a strategy of preventive war, why are target states not led by better-later-than-now logic to adopt a strategy of buying time, and why are they sometimes oblivious to the declining state’s strategic calculus? I am working with historian William Mulligan to explore this puzzle in the case of Russia in the First World War. Eventually, I plan to integrate all of this work into a book length treatment of preventive war.

I am also continuing my earlier work on power transition theory. After a couple of earlier review essays (1999, 2008), I am now working with Andrew Greve on the power transition in the late 19th century between China and rising Japan. We link the key power transition variable of (dis)satisfaction with the status quo to status ambitions. We also emphasize the inseparability of the regional power transition in East Asia from broader patterns in the global system, including industrialization.  

Domestic Politics and War

My work on domestic politics and war goes back to a 1988 review essay, the development of the diversionary theory of war (1989, 1992), and analyses of the domestic sources of alliance formation with Michael Barnett (1991, 1992). In recent work I have developed one neglected implication of diversionary theory. If diversionary theory is correct that political leaders sometimes have incentives to use military force against external actors for the primary purpose of bolstering their domestic political support, domestic oppositions may have the opposite incentives and adopt the politically risky strategy of actively opposing war. This phenomenon of politically-motivated opposition to war (2004) has important implications for interstate bargaining theories. It suggests, contrary to the arguments of Kenneth Schultz and other signaling and bargaining theorists, that the behavior of the domestic opposition does not in itself send an unambiguous signal of the government’s intentions. Patrick Shea, Terrence Teo, and I followed up this study with a collaborative study with formal model of the strategic dynamics involved, and applied them to US behavior in the Quasi-War with France in 1798. I am working on a different pattern of strategic behavior between governments and oppositions with Patricia Young, summarized by our title “When Leaders Want Peace and Oppositions Want War.”

I have recently joined debates – now two decades old but intensifying – about “audience costs,” defined as the domestic costs a leader pays for making a foreign threat but then not following through on it. After a conceptual contribution to a symposium on audience costs (2012), I have joined with three colleagues to conduct an experimental study of the mechanisms driving audience costs. Departing from the standard model of examining the consequences of making threats, we argued that if publics punish leaders for inconsistency between words and deeds, we should observe punishment for failure to adhere to promises to stay out of a conflict as well as for failure to live up to threats to intervene. Our hypothesis was confirmed by our experimental study, but we found that backing down from threats generates higher levels of punishment than does intervening in a conflict after promising to stay out (2015).

The Political Economy of War and Peace

My work on the political economy of war and peace includes studies of the militarization of commercial rivalry and the relationship between economic interdependence and international conflict. The project on the militarization of commercial rivalries was motivated by the rivalry literature’s initial neglect of both the commercial roots and domestic sources of many strategic rivalries. I did two studies of the Anglo-Dutch rivalry of the 17th century and one of the Anglo-Spanish rivalry of the 18th century. This case selection was dictated by the fact that historians often interpret the 1652 and 1665 Anglo-Dutch wars and the 1739 War of Jenkins’ Ear as “pure trade wars.” An analysis of each case demonstrated that domestic politics played a critical role in the escalation of each commercial rivalry to war.

My work on economic interdependence, war, peace began with work on the impact of war and trade, motivated by the prediction of both liberal and realist theories that trade between wartime adversaries will stop or at least significantly decline with the outbreak of hostilities or before. Katherine Barbieri and I used interrupted time series analysis and historical case studies to demonstrate that this was often not the case (1999, 2001, 2004). In several current projects, I have returned to the question of the impact of economic interdependence on conflict. I am conducting a review of recent literature on economic interdependence and war. I am also doing an H-Diplo roundtable review of historian Jennifer Siegel’s book on For Peace and Money: French and British Finance in the Service of Tsars and Commissars. I am also working with historian William Mulligan on the role of economic interdependence in the processes leading to the Great War. Given the historically unprecedented levels of economic interdependence in 1914, the Great War stands as an apparent anomaly in the liberal theory that trade promotes peace, and is worth examining for that reason. In addition, the existing literature focuses on the link between interdependence and the outbreak of war, and neglects how it was expected to shape the conduct of war. That, in turn, could influence the outbreak of war, in a neglected causal path.

The Psychology of Decision-Making

After earlier efforts to apply research on prospect theory (1992, 2000, 2003), learning (1994), and time horizons (2007) to international relations, I wrote a couple of review essays on the psychology of judgment and decision-making (2003, 2013). I also served as co-editor (with Leonie Huddy and David Sears) of the second edition of the Oxford Handbook of Political Psychology (2013). Following up an earlier study with Uri Bar-Joseph on the psychological and political sources of intelligence failure (applied to Israel in the Yom Kippur War), and H-Diplo roundtables on Joshua Rovner’s Fixing the Facts book on intelligence failure (2012) and Keren Yarhi-Milo’s Knowing the Adversary (2015), I am now working with Norrin Ripsman on the question of whether intelligence drove policy or whether policy drove intelligence for Britain in the 1930s. We analytically distinguish between two distinct paths through which policy might drive intelligence: through the politicization of intelligence, and through the motivated reasoning of political leaders. We focus on the former with respect to the flawed British assessments of the German threat in the 1930s.  

Qualitative Methodology and Philosophy of Science/History

After earlier work on case study methodology (2002, 2007, 2008), and after occasionally teaching about counterfactuals at the Institute for Qualitative and Multimethod Research, I have recently published my second piece on counterfactual analysis (2015). I have been approached about doing a book on the subject, and I am thinking about that, but that would be several years off. I am also engaged in ongoing discussions about the relationship between diplomatic history and international relations theory, and how each discipline can advance by learning from the other (1997, 2001). I will be participating in a workshop of historians in Glasgow in 2016 on The Practice of International History.

The First World War

I am involved in several analytically driven projects related to the outbreak and immediate spread of the First World War. I have already mentioned studies of the strategic logic of a rising power (Russia), and of the impact of economic interdependence on conflict. I am planning additional projects. One will be a comparative study of the crises of 1905, 1908, 1911, 1912, 1913, 1914, motivated by the view that any satisfactory explanation of the outbreak of World War I needs to explain why these earlier crises, where many international and domestic conditions were similar, did not escalate to a great power war. My tentative plan is to assess the extent to which the rationalist framework developed in my 1990/91 article can explain why a great power war broke out in 1914 but not before.

British and French Grand Strategy in the 1930s

Building on our recent articles (2007, 2008, 2012), Norrin Ripsman and I are working on a book on British and French grand strategy in response to the rapid rise of Nazi Germany in the 1930s. Our basic argument is that British leaders believed that by the mid-1930s Nazi Germany had already surpassed Britain in power and that it was too late for a military confrontation. The combination of German economic weaknesses and a vigorous British rearmament program would reverse the German advantage by the late 1930s, however, allowing Britain to deter German aggression if possible or fight a war under more favorable circumstances if necessary. Thus British appeasement was driven by a “buying time” strategy, while the French were dependent on Britain.
Handbook of Great Power Wars

In an ongoing and long-term project, I hope to follow up on the quantitative study of five centuries of great power war (1983) with a multi-volume treatment of all 55-60 great power wars in the modern system since 1495. For each I will include basic data, chronologies, an interpretive essay on the outbreak, escalation, and consequences of the war, and an annotated bibliography. At this point I have decent bibliographies for all of the wars, detailed chronologies for about forty wars, and interpretive essays for about ten of them. There is nothing like this anywhere in the literature. This will take many years, and I may begin by focusing on the ten hegemonic wars in the last five centuries of the modern system. One short term project is to put my revised war data in electronic format and make it available online. 

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