# International Relations/Structural Realism
## The Premises of Structural Realism

Structural Realism usually begins with the following assumptions:
* that the international system is anarchic; that is, there is no credible power above the states that compromise the system.
* that states cannot be certain of the intentions of other states
* that at least some states have offensive capabilities
* that states have preferences which they seek to realize, and that survival is a prerequisite for realizing such a preference
From these premises, Structural Realism concludes the following: because states require survival in order to seek their preferences, they seek to survive. Because they cannot be certain of the intentions of other states, which may have offensive capabilities, and because there is no higher authority which can protect them from those other states, it is rational for states to seek some optimal level of power relative to all other states in the system. Relative power can then be used as a means to survival, and therefore a means to the state's true preferences.
The result is an international system in which each state competes with every other state for relative power. While power is an unlimited resource, the competition is, in effect, zero sum, because what is important is how powerful a state is relative to all other states. An increase in absolute power for one state and no change in absolute power for all other states will mean a decrease in relative power for all other states.
Note that, in Structural Realism, states must seek power before being able to realize their preferences. Therefore, the structural imperative to seek power will, in Structural Realism, tend to override any contrary preferences that the state has, at least for a rational state. In this way, Structural Realism posits that the driving factor behind a rational state's foreign policy is not internal politics or preferences, but an externally-determined set of structural imperatives. For this reason, Structural Realists can be very dismissive of a state's domestic politics.
Structural Realists can be further divided into Offensive and Defensive Realists, based on how much power they believe is optimal. Defense Realists posit that there is some ideal level of power which a state should seek; below that level, it cannot be guarenteed of its own security, but above that level, other states will begin to see it as a threat and counter-balance it. Offensive Realists hold that states should maximize their power, since the collective action problem will impede counter-balancing.

#### Modified Structural Realism

Modified Structural Realism is the result of an effort by Robert O. Keohane to improve the theories of Classical and Structural Realism adding some basic assumptions from Idealist theories.
Key assumptions:
* Sovereign states are the principal actors in the international system.
* Emphasis is given to the role of non governmental organizations and international/ multinational organizations.
* States are rational unitary actors each moving towards their own national interest.
* States always try to maximise their military power but they are also interested in maximizing other forms of power such as "soft power".
* The definition of national interests is affected by the structure of the international system and also by internal factors such as public opinion. However, internal characteristics do not shape state behavior in the international system; the anarchic structure of the international system itself does.
Modified Structural Realism cures some of the weaknesses of the theories stated above especially concerning the effective use of the state's power and the role and function of the international regimes.