[1] Whereas realism and liberalism make broad and specific predictions about international relations, constructivism and rational choice are methodological approaches that focus on certain types of social explanation for phenomena.
[4] The modern study of international relations, as a theory, has sometimes been traced to realist works such as E. H. Carr's The Twenty Years' Crisis (1939) and Hans Morgenthau's Politics Among Nations (1948).
[citation needed] During the late 1980s and 1990s, constructivism emerged as a prominent third IR theoretical framework, in addition to existing realist and liberal approaches.
It assumes that nation-states are unitary, geographically based actors in an anarchic international system with no authority above capable of regulating interactions between states as no true authoritative world government exists.
[16] According to neo-realists, structure is considered an extremely important element in IR and is defined in a twofold manner as: 1) the ordering principle of the international system, which is anarchy, and 2) the distribution of capabilities across units.
[citation needed] Robert O. Keohane and Joseph S. Nye, in response to neorealism, developed an opposing theory they dubbed "complex interdependence."
The heart of Keohane and Nye's argument is that, in international politics, there are, in fact, multiple channels that connect societies exceeding the conventional Westphalian system of states.
"[27] One version of post-liberal theory argues that within the modern, globalized world, states in fact are driven to cooperate in order to ensure security and sovereign interests.
[28] Another version of post-liberalism, drawing on work in political philosophy after the end of the Cold War, as well as on democratic transitions in particular in Latin America, argues that social forces from below are essential in understanding the nature of the state and the international system.
Furthermore, the impact of social forces on political and economic power, structures, and institutions, provides some empirical evidence of the complex shifts currently underway in IR.
[34] The key element of constructivism is the belief that "International politics is shaped by persuasive ideas, collective values, culture, and social identities."
By "ideas" constructivists refer to the goals, threats, fears, identities, and other elements of perceived reality that influence states and non-state actors within the international system.
For example, constructivists note that an increase in the size of the U.S. military is likely to be viewed with much greater concern in Cuba, a traditional antagonist of the United States, than in Canada, a close U.S. ally.
Marxist and Neo-Marxist international relations theories are structuralist paradigms which reject the realist/liberal view of state conflict or cooperation; instead focusing on the economic and material aspects.
Marxist approaches argue the position of historical materialism and make the assumption that the economic concerns transcend others; allowing for the elevation of class as the focus of study.
Criticisms of Marxists approaches to international relations theory include the narrow focus on material and economic aspects of life, as well as assuming that the interests pursued by actors are derived from class.
Post-structuralism differs from most other approaches to international politics because it does not see itself as a theory, school or paradigm which produces a single account of the subject matter.
Scholars associated with post-structuralism in international relations include Richard K. Ashley, James Der Derian, Michael J. Shapiro, R. B. J. Walker,[42] and Lene Hansen.
In her seminal book, Women and War, Elshtain criticizes gender roles inherent in mainstream international relations theory.
[46] For example, Enloe uses banana plantations to illustrate how different women are affected by international politics depending on their geographical location, race, or ethnicity.
This piece of Tickner's was met with criticism from multiple scholars, such as Robert Keohane, who wrote "Beyond Dichotomy: Conversations Between International Relations and Feminist Theory"[47] and Marianne Marchand, who criticized Tickner's assumption that feminist international relations scholars worked in the same ontological reality and epistemological tradition in her piece "Different Communities/Different Realities/Different Encounters".
[49] In the 1970s, scholars of world politics started drawing on new research in cognitive psychology to explain decisions to cooperate or compete in international relations.
For example, Robert Jervis identified patterns of leaders' misperception in historical cases that led to unwanted escalation, failures of deterrence, and the outbreak of war.
[50] Deborah Welch Larson and Rose McDermott have referred to belief systems and schemas as central drivers of information processing and foreign policy decision-making.
[53] More recently, scholars of international relations have started drawing on emotion research in psychology to shed light on issues in world politics.
For example, Rose McDermott and Jonathan Mercer were among the first to use these new findings to argue that affective experience can have adaptive functions by facilitating quick and effective decision-making.
[64][65] A 2016 study showed that while theoretical innovations and qualitative analyses are a large part of graduate training, journals favor middle-range theory, quantitative hypothesis testing and methodology for publishing.
Instead of testing maxims systematically to determine whether they are true, behaviouralists view proponents of ideological isms as spreading propaganda in the guise of scholarship to guide policy-makers.
[68] Theories previously developed in economics and sociology are applied to international affairs, while the major isms, such as realism, are reconstituted into a form that can be tested systematically with comprehensive databases.
Behavioural scholars seek to retrofit isms identified above into variants of existing paradigms that can be tested empirically, whereupon the future of international relations theory will move beyond untested maxims to a solid foundation of knowledge.