In This Article Expand or collapse the "in this article" section Balance of Power

  • Introduction
  • Definitions and Meaning
  • Balance-of-Power Mechanisms
  • Balance of Power as Manual or Automatic
  • Balance of Power in International Law
  • Balance of Power in History
  • Balance of Power in the First Half of the 20th Century
  • Balance of Power during the Cold War
  • Balance of Power in the Post–Cold War Era
  • Alternatives to Balance of Power in History
  • Newer Interpretations: The Soft-Balancing Debate
  • Criticisms
  • The Future of Balance of Power

International Law Balance of Power
Erik Underwood, T.V. Paul
  • LAST REVIEWED: 15 January 2020
  • LAST MODIFIED: 15 January 2020
  • DOI: 10.1093/obo/9780199796953-0202


Balance of power is one of the most discussed and contested theoretical and policy concepts in international relations. It is in fact the bedrock of realism of all varieties, in particular classical and structural, and it is the most significant variable in systemic theories of international stability. The idea of balancing power has been popular since 17th-century Europe, although it was around in some fashion in ancient Greek, Indian, and Chinese statecraft. Beginning with the Treaty of Westphalia in 1648, it took a prominent role in legal and political thought, with legal theorists and policymakers seeing the concept as central to considerations of international law and strategy. The fact that balance of power has found enduring relevance to scholars and policymakers throughout the ages suggests that the theory is one whose value should be carefully considered. The theory holds that when power is balanced among competing states, peace is obtained, but disequilibrium in power means a strong state can attack a weaker state and rob the latter of its security and independence. The goal of balance of power is to prevent any power from becoming too strong, first by deterring aggression, but if that fails, by ensuring that the aggressor does not significantly alter the balance of power. For realists, balance of power is born in the crucible of international anarchy. It is either a tool that states manually use to keep the power and aggressive behavior of other states in check, or a state of affairs generated by power competition among states. According to realism, states fear other states, and international anarchy creates a self-help system where one’s own strength and ability to find allies with similar interests are the only means to achieve security.

Definitions and Meaning

Haas 1953 offers some eight meanings and definitions of balance of power, showing how difficult it is to define the concept. While empirically the balance of power often refers to a description of the relative military balance between states, in international-relations theory the most commonly accepted definitions refer to an equilibrium of power between states that preserves stability and peace. Morgenthau 2006 defines a balance of power as “stability in a system composed of a number of autonomous forces. Whenever the equilibrium is disturbed either by an outside force or by a change in one or the other elements composing the system, the system shows a tendency to re-establish either the original or a new equilibrium.” For Waltz 1979 the balance of power refers to an equilibrium of power in the international system that states, as the units in the system, will achieve through their individual efforts at self-preservation. To structural and neorealists the question is not whether a balance of power will be achieved, but what distribution of power will be obtained under it. Power distributions are defined either as multipolar, with three or more great powers; bipolar, with two great powers; and unipolar, with power concentrated in one great power. It is also important to distinguish between a balance of power and balancing, the latter referring to efforts or strategies seeking to constrain the power of others, sometimes for the purpose of seeking a balance of power. For Rosecrance 2003 there is a set of stringent criteria to identify balancing by a state: it must be motivated by defensive and not offensive purposes, when seeking allies it must join the weaker coalition, and it must be willing to defend its allies and restore the balance of power when threatened. For Mearsheimer 2014, balancing is something that self-interested states engage in to check the power-maximizing ambitions of their peers. The author defines balancing as where “threatened states seriously commit themselves to containing their dangerous opponent.” Alternatively, Walt 1987 argues that states do not balance purely against power; they balance against threat, and power is just one element that generates threat.

  • Haas, Ernst B. “The Balance of Power: Prescription, Concept, or Propaganda?” World Politics 5.4 (1953): 442–477.

    DOI: 10.2307/2009179

    In this classic article, in the context of the onset of the Cold War, Haas discusses the various ways in which scholars of his time understood balance of power in terms of (1) the distribution of power, (2) equilibrium, (3) hegemony, (4) stability and peace, (5) instability and war, (6) power politics in general, and (7) a universal law of history, as well as (8) a system and guide to policymaking.

  • Mearsheimer, John J. The Tragedy of Great Power Politics. New York: W. W. Norton, 2014.

    In this book, Mearsheimer develops his theory of offensive realism, arguing that because states can never be certain of the intentions of other states, looking only to their power to determine their intentions, states must maximize their power, with each seeking to become a regional hegemon. Here every state is a potential aggressor and must be balanced.

  • Morgenthau, Hans J. Politics among Nations: The Struggle for Power and Peace. Boston: McGraw-Hill Higher Education, 2006.

    In this classical text, Morgenthau develops a theory of international politics that, among a wide variety of subjects, covers balance of power. For Morgenthau, states seek power because of an innate desire of humans for power and prestige, and power has many elements, including not just material but also ideational elements of national character and morale.

  • Paul, T. V., James Wirtz, and Michel Fortmann, eds. Balance of Power: Theory and Practice in the 21st Century. Stanford, CA: Stanford University Press, 2004.

    This colleciton of essays contains theoretical explanations, criticisms, and regional and global applications of balance-of-power theory and policy. It aso contains valuable citations and ideas as well as changing notions of balance of power in the contemporary world.

  • Rosecrance, Richard. “Is There a Balance of Power?” In Realism and the Balancing of Power: A New Debate. Edited by J. A. Vasquez and C. Elman. Upper Saddle River, NJ: Prentice Hall, 2003.

    In this book chapter, Rosecrance critiques definitions of balance of power which he argues define the concept too broadly. He provides a narrower definition to try to more accurately capture empirical cases: a state must be motivated by defensive purposes, when balancing through alliances it must join the weaker coalition, and it must be willing to defend those allies and the balance of power.

  • Walt, Stephen. The Origins of Alliances. Ithaca, NY: Cornell University Press, 1987.

    In contrast to Kenneth Waltz’s structural realism and offensive realists such as Mearsheimer, Walt argues that states balance against threat. Aggregate and offensive power are seen as generators of threat, but geographical proximity influences the ability to project power, and states are concerned over whether other states possess aggressive intentions. Each of these decides whether a state sees a threat, and balances against that threat.

  • Waltz, Kenneth N. Theory of International Politics. Reading, MA: Addison-Wesley, 1979.

    In this seminal text, Watlz develops the theory of structural realism, which sees anarchy as the key driver of conflict, since with no higher power, states must rely on self-help. He develops a theory of balance of power, arguing that states will automatically form balances of power against more-powerful states, and that the main variation that will occur will be between bipolar (power concentrated in two great powers) or multipolar systems (power concentrated three or more great powers), with the former more stable.

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