Realist school of international relations

According to leading international relations website E-International Relations:

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The first assumption of realism is that the nation-state (usually abbreviated to ‘state’) is the principle actor in international relations. Other bodies exist, such as individuals and organisations, but their power is limited. Second, the state is a unitary actor. National interests, especially in times of war, lead the state to speak and act with one voice. Third, decision-makers are rational actors in the sense that rational decision-making leads to the pursuit of the national interest... Realism is a theory that claims to explain the reality of international politics. It emphasises the constraints on politics that result from humankind's egoistic nature and the absence of a central authority above the state.

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