realism, set of related theories ofinternational relations that emphasizes the role of thestate, national interest, and power in world politics.

Realism has dominated the academicstudy of international relations since the end ofWorld War II. Realists claim to offer both the most accurate explanation of state behaviour and a set of policy prescriptions (notably thebalance of power between states) forameliorating theinherent destabilizing elements of international affairs. Realism (including neorealism) focuses onabiding patterns of interaction in an international system lacking a centralized political authority. That condition ofanarchy means that the logic of international politics often differs from that of domestic politics, which is regulated by asovereign power. Realists are generally pessimistic about the possibility of radical systemic reform. Realism is a broad tradition of thought thatcomprises a variety of different strands, the most distinctive of which are classical realism and neorealism.

Classical realism in international relations

Realists frequently claim to draw on an ancient tradition of political thought. Among classic authors often cited by realists areThucydides,Niccolò Machiavelli,Thomas Hobbes,Jean-Jacques Rousseau, andMax Weber. Realism as a self-conscious movement in the study of international relations emerged during the mid-20th century and was inspired by the British political scientist and historianE.H. Carr. Carr attacked what he perceived as the dangerous and deluded “idealism” ofliberal internationalists and, in particular, their belief in the possibility of progress through the construction of international institutions such as theLeague of Nations. He focused instead on theperennial role of power and self-interest in determining state behaviour. The outbreak ofWorld War II converted many scholars to that pessimistic vision. Thereafter, realism became established in Americanpolitical science departments, its fortunes boosted by a number of émigré European scholars, most notably the German-born political scientist and historianHans Morgenthau. It is the realism of Carr, Morgenthau, and their followers that is known as classical.

Morgenthau’s Politics Among Nations (1948) helped to meet the need for a general theoretical framework for realism. Not only did it become one of the most extensively used textbooks in the United States and Britain—it continued to be republished in new editions over the next half century—it also was an essentialexposition of the realist theory of international relations. Numerous other contributors to realist theory emerged in the decade or so after World War II, including Arnold Wolfers, George F. Kennan, Robert Strausz-Hupé,Henry Kissinger, and the theologian Reinhold Niebuhr.

According to realism, states exist within an anarchic international system in which they are ultimately dependent on their own capabilities, or power, to further their national interests. The most important national interest is the survival of the state, including its people, political system, and territorial integrity. Other major interests for realists include the preservation of a nation’s culture and economy. Realists contend that, as long as the world is divided intonation-states in an anarchic setting, national interest will remain the essence of international politics.

Classical realism was not acoherent school of thought. It drew from a wide variety of sources and offered competing visions of the self, the state, and the world. Whereas Carr was influenced byMarxism, Morgenthau drew onFriedrich Nietzsche, Weber,Carl Schmitt, and Americancivic republicanism. Classical realists were united mainly by that which they opposed. Critical of the optimism and explanatory ambition of liberal internationalists, classical realists instead stressed the various barriers to progress and reform that allegedly inhered inhuman nature, in political institutions, or in the structure of the international system. The fortunes of classical realism, grounded as it was in a combination ofhistory,philosophy, andtheology,waned during the era of social-scientificbehaviourism in the 1960s. Its fortunes were revived by the emergence of neorealism during the 1970s.