The debate between realists and liberals has reemerged as an axis of contention in international relations theory. Revolving in the past around competing theories of human nature, the debate is more concerned today with the extent to which state action is influenced by “structure” (anarchy and the distribution of power) versus “process” (interaction and learning) and institutions. Does the absence of centralized political authority force states to play competitive power politics? Can international regimes overcome this logic, and under what conditions? What in anarchy is given and immutable, and what is amenable to change?

The discipline of international relations faces a new debate of fundamental significance. After the realist challenge to the pervasive idealism of the interwar years and the social scientific argument against realism in the late 1950s, it is now the turn of critical theorists to dispute the established paradigms of international politics, having been remarkably successful in several other fields of social inquiry. In essence, critical theorists claim that all social reality is subject to historical change, that a normative discourse of understandings and values entails corresponding practices, and that social theory must include interpretation and dialectical critique. In international relations, this approach particularly critiques the ahistorical, scientific, and materialist conceptions offered by neorealists. Traditional realists, by contrast, find a little more sympathy in the eyes of critical theorists because they join them in their rejection of social science and structural theory. With regard to liberal institutionalism, critical theorists are naturally sympathetic to its communitarian component while castigating its utilitarian strand as the accomplice of neorealism. Overall, the advent of critical theory will thus focus the field of international relations on its “interparadigm debate” with neorealism.

As the world moves away from the familiar bipolar cold war era, many international relations theorists have renewed an old debate about which is more stable: a world with two great powers or a world with many great powers. Based on the chief assumptions of structural realism—namely, that the international system is characterized by anarchy and that states are unitary actors seeking to survive in this anarchic system—some security analysts are predicting that a world of several great powers will lead to a return to the shifting alliances and instabilities of the multipolar era that existed prior to World War II. For instance, John Mearsheimer argues that “prediction[s] of peace in a multipolar Europe [are] flawed.” Thomas Christensen and Jack Snyder argue that states in a multipolar world can follow either the pre-World War I or the pre-World War II alliance pattern, thus implying that a third course is improbable. They further assert that “the fundamental, invariant structural feature, international anarchy, generally selects and socializes states to form balancing alignments in order to survive in the face of threats from aggressive competitors.” The realist argument predicts that great powers in a self-help international system will balance one another through arms races and alliance formations.

There is a distinctively repetitive quality about trade policy problems. Domestic economic growth slows; producers seek protection against foreign competitors; and national decision makers raise barriers to trade while at the same time criticizing their counterparts in other governments for engaging in similar practices. Because trade is one of the more important topics in international and comparative political economy and because this scenario has played itself out more than a few times, it is not surprising that a number of theorists have sought to model the underlying processes thought to produce movements toward and away from protectionism.

The decision of the European Community (EC) members to complete their “internal market” by the end of 1992, as embodied in the 1987 Single European Act (SEA), may represent the most ambitious instance of multilateral cooperation since the construction of the post-World War II international order. The economic objective of internal market completion is the removal of a wide array of nontariff barriers to trade that elsewhere have proved politically intractable, including border controls, national standards, preferential procurement policies, and industrial subsidies. The institutional structures underpinning the internal market are more constraining on the behavior of sovereign states than has been the case for other international regimes. The SEA replaced unanimity voting (national vetoes) in the primary decision-making body of the EC, the Council of Ministers, with a system of majority voting over matters pertaining to the internal market. In addition, the internal market is buttressed by an elaborate and powerful legal system. EC law is considered to have supremacy over national laws and to have “direct effect” in domestic jurisdictions, regardless of whether it is explicitly incorporated through legislation.