Differences between defensive realism and offensive realism

Comparison: Defensive realism vs. offensive realism

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Defensive realism and offensive realism are theories within the school of realism in international relations theory that provide distinct assumptions that collectively explain the behaviors and actions of states relative to the supposed anarchy in the international system.

Similarities between defensive realism and offensive realism

Before discussing the differences between defensive realism and offensive realism however, it is first important to understand their similarities.

Remember that both theories are derivatives of realism. One of their general assumptions is that states are the primary actors in the international system and there are no other actors that can regulate their conduct. Even supranational organizations have no real authority over state actors.

Another similarity between defensive realism and offensive realism is that both assert that the international system is inherently anarchic because states are primarily and perpetually driven to maintain power and promote security. Their behaviors and actions are driven by self-interest and the need to survive.

Both theories also assume that states can never be certain about the true intentions of other states. However, both also assert that states are rational actors that are capable of developing and implementing strategies that maximize their prospect of survival.

Differences between defensive realism and offensive realism

Defensive realism and offensive realism first emerged from the separate and contradicting works of two American political scientists. To be specific, defensive realism traces its roots from the 1979 book “Theory of International Politics” by Kenneth Waltz while offensive realism finds its foundation from the 2001 book “The Tragedy of Great Power Politics” by John J. Mearsheimer.

The aforementioned works provided the groundwork used by adherents to further expand and enrich either of the two theories. Nonetheless, the following are the specific differences between defensive realism and offensive realism:

1. Core Arguments: Defensive realism asserts that states develop and maintain policies and programs aimed at promoting security through a defensive approach. On the other hand, offensive realism asserts that the programs and policies developed and maintained by states are aimed not only at promoting security but also at increasing their power to dominate the international system. Thus, one of the major differences between defensive realism and offensive realism centers on their respective interpretations and expansions of the general assumptions of realism.

2. Handling Anarchy: The international system is inherently anarchic according to the school of realism of international relations theory. Defensive realism contends that states navigate through anarchy by balancing their power through arms race or capability-building. An imbalance resulting from a state pursuing dominance is counterbalanced by other states seeking to maintain the status quo. The international system punishes aggressors according to defensive realists. However, offensive realism argues that states inherently desire dominance because they are power-maximizing actors. Furthermore, offensive realists believe that the international system rewards states that are able to secure and maintain their dominance.

3. Purpose of Military: The primary purpose of military of a particular state under defensive realism is to maintain security by having the capacity for defending against aggressors. In addition, defensive capability is superior over offensive capabilities. The collective military capabilities of different states also create a stabilizing effect. Meanwhile, offensive realism argues that the primary purpose of military is to display the power of a state through aggression, thus further depressing threats from other states.

4. State Survival: States are driven by self-interest and self-preservation through power and security. Defensive realists and offensive realists both agree to this fact. However, defensive realists specifically believe that states are only interested about maintaining their security through defensive measures while offensive realists think that states are interested in conquest and that the best way to survive is to demonstrate their power and prevent others states from attaining similar level of power.

5. View on Mistrust: Another difference between defensive realism and offensive realism is the way each of them analyze the concept of mistrust. Both theories claim that because states can never be absolute about the true and specific intentions of other states, mistrust is pervasive among these actors. Offensive realism specifically argues that mistrust is not only prevalent but also constant. However, defensive realism contends that mistrust is variable and amenable to change through international cooperation, primarily through mutual security agreements.


  • (1) Mearsheimer, J. J. 2001. The Tragedy of Great Power Politics. New York: W. W. Norton
  • (2) Waltz, K. N. 1979. Theory of International Politics. New York: McGraw Hill