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International relations (IR) is an academic and public policy field, a branch of political science, dealing with the foreign policy of states within the international system, including the roles of international organizations, non-governmental organizations (NGOs), and multinational corporations (MNCs). Because international relations seeks to analyze as well as formulate foreign policy, it can be either positive or normative.
It draws upon such diverse fields as political science, economics, history, law, philosophy, area studies, sociology, cultural studies and other social sciences. International relations involves a diverse range of issues, including the environmental movement, nuclear proliferation, nationalism, foreign aid, economic development, and human rights.
There are many ways of thinking in international relations theory, including Constructivism, Institutionalism, Marxism, Neo-Gramscianism, and others. However, two schools of thought are predominant: Realism and Liberalism.
The term Realism is often associated with the German term realpolitik. Realpolitik is a combination of two words: the German "real", meaning "real" or "substantive," as in the German "Realität" (meaning "reality"), and "politik" (meaning "politics" or "policy"). Bismarck used the term after following Metternich's lead in finding ways to balance the power of European empires. Balancing power meant keeping the peace, and careful realpolitik practioners tried to avoid arms races. However, during the early-20th Century, arms races (and alliances) occurred anyway, culminating in World War I.
Realism makes several key assumptions. It assumes that the international system is anarchic, in the sense that there is no authority above states capable of regulating their interactions; states must arrive at relations with other states on their own, rather than it being dictated to them by some higher controlling entity (that is, no true authoritative world government exists). It also assumes that sovereign states, rather than international institutions, non-governmental organizations, or multinational corporations, are the primary actors in international affairs. According to realism, each state is a rational actor that always acts towards its own self-interest and the primary goal of each state is to ensure its own security. Realism holds that in pursuit of that security, states will attempt to amass resources and that relations between states are determined by their relative level of power. That level of power is in turn determined by the state's capabilities, both military and economic. Moreover, Realists believe that States are inherently aggressive ("offensive realism"), and that territorial expansion is only constrained by opposing power(s). The principal Realist theorists are Carr, Morgenthau and Waltz.
There are two sub-schools of realism: maximal realism and minimal realism. The theory of maximal realism holds that the most desirable position to be in is that of the hegemon]], the most powerful entity in the world, and that smaller entities will align themselves with the hegemon out of political self-interests. Under maximal realism, the position where there are simultaneously two equally powerful co-hegemons (such as was the case during the Cold War between the United States and the Soviet Union) is an inherently unstable one and that situation will inevitably collapse into a more stable state where one nation is more powerful and one is less powerful.
The theory of minimal realism holds that non-hegemonic states will ally against the hegemon in order to prevent their own interests from being subsumed by the hegemon's interests. Under the minimal-realism theory it is possible to have two equally powerful co-hegemons with whom a smaller entity may ally in turn depending on which hegemon better fits with the smaller entity's policies at the moment (playing both sides against the middle).
Liberalism holds that state preferences, rather than state capabilities, are the primary determinant of state behavior. Preferences will vary from state to state, depending on their culture, economic system, or type of government. Many different strands of liberalism have emerged; some include commercial liberalism, liberal institutionalism, idealism and regime theory.
Recently, realism and liberalism have evolved into neo-realism and neo-liberalism. no
Other Schools of Thought
Other schools, which cannot (yet) be counted to the established mainstream in the Study of International Relations, include postmodern, feminist and Neo-Marxist approaches, and Neo-Gramscianism. These perspectives differ from both Realism and Liberalism in their epistemological and ontological premises and are postpositivistic in nature.
Different schools of thought in international relations can predict the same events. The theories are differentiated by the assumptions they make in their reasoning toward predictions. For example, both realists and liberals claim that events as disparate as World War I, the Cold War, and the relatively conflict-free post-Cold War Europe were predicted by their theories. The theories differ in the fundamental assumptions they make in predicting state behavior. It is possible that one liberal theorist will predict war while another liberal theorist will predict peace; their disagreement arises from how they interpret events, but their fundamental assumptions are the same. Similarly, it is possible that a realist theorist and a liberal theorist could both predict peace, but their fundamental assumptions as to why that occurs would be different. _
The history of international relations is widely traced back to the Peace of Westphalia of 1648 where the modern states system as we see it today was developed. It was not until 1919 that the first university department devoted to 'international politics' (and its Woodrow Wilson Chair of International Politics) was founded by David Davies at the University of Aberystwyth in Wales. The first university to found an international relations department was the London School of Economics in 1924.
- Cambridge Review of International Affairs, ,
-  ISSN 0955-7571
- The Economist,
- European Journal of International Relations, 
- Foreign Affairs
- Foreign Policy
- Georgetown Journal of International Affairs
- International Affairs ISSN (print) 0020-5850, ISSN (online) 1468-2346
- International Organization,  ISSN 0020-8183
- International Security
- International Studies Quarterly,  ISSN (print) 0020-8833, ISSN (online) 1468-2478
- Journal of International Affairs
- The Global Civil Society Yearbook (London School of Economics)
- Millennium Journal of International Studies (London School of Economics)
- McGill International Review
- The National Interest
- Orbis (Foreign Policy Research Institute)
- The SAIS Review (Johns Hopkins University), ISSN (print) 0036-0775, ISSN (online) 1088-3142
- Journal of Public and International Affairs (Princeton University)