- Realism is one of the dominant schools of thought in international relations theory, theoretically formalising the Realpolitik statesmanship of early modern Europe. Although a highly diverse body of thought, it is unified by the belief that world politics is always and necessarily a field of conflict among actors pursuing power. The theories of realism are contrasted by the cooperative ideals of liberalism. Realists can be divided into three classes based on their view of the essential causes of interstate conflict. Classical realists believe it follows from human nature; neorealists attribute it to the dynamics of the anarchic state system; neoclassical realists believe it results from both, in combination with domestic politics. Neorealists are also divided between defensive and offensive realism. Realists trace the history of their ideas back through classical antiquity, beginning with Thucydides. Jonathan Haslam characterizes realism as "a spectrum of ideas." Its theories revolve around four central propositions: 1.
* states are the central actors in international politics, rather than leaders or international organizations; 2.
* the international political system is anarchic, as there is no supranational authority to enforce rules; 3.
* states act in their rational self-interest within the international system; and 4.
* states desire power to ensure self-preservation. Realism is often associated with realpolitik, as both deal with the pursuit, possession, and application of power. Realpolitik, however, is an older prescriptive guideline limited to policy-making, while realism is a wider theoretical and methodological paradigm to describe, explain, and predict events in international relations. As an academic pursuit, realism is not tied to ideology; it does not favor any particular moral philosophy, nor does it consider ideology to be a major factor in the behavior of nations. Priorities of realists have been described as Machiavellian, single-mindedly seeking the power of one's own nation over others. (en)