Spiral Model

The spiral model is a concept in international relations that describes how well-intentioned, defensively motivated states can find themselves in an unintended arms race or even war with other similarly motivated states because of the difficulty of assessing state intentions in the absence of a supranational government. This dilemma is caused by the fact that the means one state uses to make itself more secure often have the unintended consequence of making other states less secure. Such an outcome is an example of how individually rational decisions can sometimes result in collectively suboptimal outcomes. In its view of state intentions and of the effects of one state's armament decisions on other states' behavior, the spiral model sits in stark opposition to the theory of deterrence.

[Page 626]Anarchy, or the absence of a centralized government, in the international system is the ultimate source of the unintended outcomes characteristic of the spiral model. A state in such an environment must develop armaments and seek other ways of protecting itself from states with potentially malignant intentions. However, because many weapons that can be used for defense can also be used for offense, other states read these defensive actions as potentially threatening and reciprocate by increasing their own military capacities. This in turn makes the first state more fearful, thereby setting off a spiral of increasing hostility and armament that can lead to war. This situation in which one state's efforts to improve its own security often backfire by provoking unexpected reactions from other states is often described as the security dilemma. Psychological dynamics—such as the tendency to assimilate discrepant information to previously formed beliefs—may make the dilemma more acute, though its basic roots lie in the structure of the system.

Robert Jervis has argued that two variables affect how severe this dilemma is apt to be: (1) the distinguishability of offensive from defensive weapons and (2) whether offensive or defensive weapons have the advantage. Because a central cause of the security dilemma lies in the fact that weapons used for defensive purposes can likewise be used for offensive ends, the dilemma does not theoretically operate during historical epochs when military technology makes it possible to clearly distinguish offensive armaments from defensive. However, making such a clear-cut distinction is rarely possible. Moreover, the dilemma will be especially vicious when existing technology and geography make it easier to conquer than to defend territory.

Deterrence theory, in contrast, presents a strikingly different view of state intentions and behavior and starts by making opposing assumptions about the intentions of the potential enemy state. While the spiral model assumes innocuous or defensive intentions on the part of the other state, deterrence theorists assume that this state has malignant or expansionist intentions. In international relations language, the spiral model assumes that the other state is a status quo power, while deterrence theorists view this state as a revisionist power. Because of this deterrence theorists emphasize not the danger of a misunderstanding between two defensively motivated states, but rather the danger that an aggressor will be emboldened by any conciliatory gesture. According to deterrence theorists, as long as the state's power level permits, it is often appropriate to take a hard-line stance in response to the potentially threatening actions of another state, lest the other state read attempts at compromise as evidence of weakness and lack of will. The quandary here is obvious: deterrence theorists recommend the same policy measures that the spiral model predicts will lead to an unnecessary increase in hostility and even war. Determining which model is most appropriate in a given situation ultimately depends on forming accurate assessments about the intentions of the opposing state, a notoriously difficult task.

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