International relations as an academic field of study has evolved significantly over the past century, with various schools of thought emerging to explain and analyze the complex dynamics between nation states. Key political concepts such as power, anarchy, cooperation, institutions etc. have been defined and reinterpreted through different theoretical lenses. This article will provide an overview of the major political concepts in international relations theory and how they have developed over time, referencing 50 seminal works on the subject.
Realism and the Concept of Power
Classical realism emerged in the aftermath of World War II, with scholars such as Hans Morgenthau, George Kennan and E.H. Carr rejecting the idealistic approach to international relations that had dominated the interwar period.  Realists argued that international politics was fundamentally about power and security in an anarchic world order, with sovereign states as the main actors. 
Morgenthau in his book Politics Among Nations defined power as anything that establishes control over the minds and actions of others.  Military and economic capabilities were seen as key sources of power. The concept of the balance of power, whereby stability is achieved through states counterbalancing each other’s power, was central to realist theory.  Kenneth Waltz later added a structural realist dimension, arguing in his Theory of International Politics that the anarchic structure of the international system compels states to pursue power. 
Other realist scholars like Robert Gilpin focused on power transition theory and hegemonic war, analyzing how the rise and fall of leading powers over time shaped geopolitics.  Stephen Krasner examined different dimensions of power and sovereignty.  Overall, realism placed power and security competition at the heart of international relations.
Liberalism and the Role of Institutions
Liberal institutionalism emerged in the 1970s as a challenge to realist dominance, emphasizing the role that international institutions, regimes and norms play in shaping state behavior.  Institutions are defined as the “rules of the game”. 
Key works include Robert Keohane’s After Hegemony, which argues that cooperation can continue even without hegemonic leadership, sustained by institutionalized relationships.  International Regimes by Stephen Krasner focuses on how contractual norms and principles embedded in institutions can facilitate cooperation. 
Liberal institutionalists do not reject power politics entirely, but argue that institutions help mitigate anarchy and enable collective gains through issue-specific or regional cooperation.  Andrew Moravcsik outlines liberal theories of international politics rooted in domestic politics and transnational interdependence. 
Overall, liberalism highlights the possibilities for cooperation, interdependence and international governance within a rules-based order.
Marxism and Critical Theories
Marxist and critical approaches view the international system as deeply shaped by capitalist forces and resulting in exploitation, domination and inequality. 
Key texts include Imperialism by Lenin, which examines the competitive logic of capitalist expansion.  World Systems Theory by Immanuel Wallerstein analyzes the historical development of the global capitalist system with its exploitative core-periphery structure. 
Robert Cox combines Gramscian theory and historical materialism to explain how dominant material capabilities and collective images of world order favor the interests of hegemonic powers.  Critical theorists such as Robert Keohane and Joseph Nye have examined complex interdependence in the global political economy. 
Feminist IR scholars have focused on gender hierarchies and the marginalization of women’s rights in foreign policy.  Post-colonialism critically examines colonial legacies, Western dominance and the denial of indigenous voices in the international system. 
Overall, critical theories shed light on how ideological, economic and social power dynamics within the global system perpetuate structural inequalities and uneven development.
Constructivism and the Power of Ideas
Constructivism emerged in the late 1980s, emphasizing the socially constructed nature of international relations.  Key texts include Anarchy is What States Make of It by Alexander Wendt, arguing that self-help and power politics are not predetermined, but rather socially constructed through interactions, shared knowledge and norms. 
Constructivists focus on the power of ideas, norms and identity in shaping state interests and behavior, as opposed to just material capabilities.  Martha Finnemore shows how international organizations actively shape and diffuse new norms. 
Critical constructivists like Ted Hopf emphasize how identities and norms are internalized by social actors and projected outwards, constituting perceived interests and policy, often in harmful ways towards marginalized groups. 
Overall, constructivism highlights the socially constructed, intersubjective dimension of international relations, downplaying rationalist assumptions. The emphasis on norm promotion provides scope for transnational activism. 
The English School and International Society
The English school occupies a middle ground between realism and liberal internationalism.  Its founders include Hedley Bull, Martin Wight and Barry Buzan.  It emerged from the post-war study of international relations at the London School of Economics.
Key concepts include international society – referring to a society of states bound by shared norms, institutions and values; international systems – the balance of power; and world society – global civil society. 
Hedley Bull’s Anarchical Society emphasizes the duality between conflict and cooperation in international politics.  Solidarism vs pluralism debates examine strains on international society.  Overall, the English school focuses on the social, ethical and normative dimensions underlying world order.
Neo-Marxism and Dependency Theory
Neo-Marxist theory rose to prominence in the 1960s and 1970s through dependency theory, pioneered by scholars like Andre Gunder Frank, Theotonio Dos Santos and Walter Rodney. 
It holds that the global capitalist system inherently disadvantages and exploits the peripheral ‘satellite’ states in the Global South, maintaining their dependence on the industrialized core economies.  Dependency is actively reinforced through political and corporate elites. 
World-systems analysis by Immanuel Wallerstein also emerged within this paradigm, focusing on the dynamic relationship between the core, periphery and semi-periphery.  Neo-Marxist scholars called for self-reliance and restrictions on neo-imperialist foreign capital. 
Dependency theory fell out of favor in the 1980s as governments moved away from import substitution and many Marxist predictions failed to materialize.  However, the neo-Marxist paradigm continues to shape critical development studies and responses to globalization.
Neoliberalism and Global Governance
Neoliberalism rose to prominence in the 1980s under leaders like Reagan and Thatcher, promoting market deregulation, privatization, free trade, reduced government spending and inflation targeting. 
In international relations, neoliberals advocate liberal democratic governance and institutions to support global free markets.  Global governance institutions such as the IMF, World Bank and WTO promote neoliberal policies worldwide. 
Critics argue neoliberal policies exacerbate global inequality, disadvantage small producers and workers, and benefit corporations and elites.  The 2008 global financial crisis was seen as discrediting unregulated markets. 
However, neoliberalism remains influential, with collective bodies like the G20 and OECD providing forums for major economies to coordinate macroeconomic policies.  Key scholars include Robert Keohane, Joseph Nye, Anne-Marie Slaughter and John Ikenberry.
Post-Modernism and Post-Structuralism
Post-modernism and post-structuralism introduce radical skepticism towards dominant western discourses and metanarratives in international relations. 
Influenced by philosophers like Foucault, Derrida and Lyotard, post-modernism challenges conventional notions of truth and objectivity in social science.  Cynthia Weber criticizes mainstream IR theory as a masculine, Eurocentric narrative that silences marginalized voices. 
Richard Ashley focuses on deconstructing state-centric discourses and highlighting marginalized populations.  Michael Shapiro examines the colonial and patriarchal ideologies underlying western political thought. 
Overall, post-modernism problematizes power-knowledge relationships within mainstream IR theory and breaks down barriers between theory and practice.  However, critics argue it offers no substantive alternative theories. 
Green Theory and Ecologism
In recent decades, international relations scholarship has increasingly incorporated environmental concerns and sustainability. 
Green theory highlights how the unconstrained pursuit of state interests and power can lead to ecological risks and climate catastrophe.  Sustainable development calls for integrating environment and development. 
Ecologism goes further in advocating radical change of the growth-oriented capitalist system towards ecologically balanced lifestyles and degrowth.  Prominent green scholars include Jennifer Clapp, John Dryzek, Robyn Eckersley and Kate O’Neill.
Key concepts include ecological interdependence, environmental justice, climate ethics, ecological citizenship and carbon sovereignty.  Green theory links domestic consumption, global production chains, and North-South equity.  Critics argue environmental cooperation has achieved limited results.  Nonetheless green perspectives are influencing IR debates.
Foreign Policy Analysis
Foreign policy analysis (FPA) applies international relations theories to explain the foreign policy behavior and decision-making processes within states.  It links the domestic and systemic levels of analysis.
Prominent FPA scholars include James Rosenau, Graham Allison, Valerie Hudson and Christopher Hill.  Key concepts include bureaucratic politics, organizational process models, national role conceptions, and the psychological drivers of leadership. 
Realist, liberal and constructivist theories have all been applied within FPA frameworks, with implications for policymaking processes and outcomes.  For instance, Allison’s seminal Essence of Decision analyzes the organizational behavior and political bargaining during the Cuban Missile Crisis. 
FPA has been critiqued for US-centrism.  However, the subfield shed lights on the complex intersection of domestic and international factors shaping foreign policy.
Critical geopolitics emerged in the 1980s and 90s led by scholars like Simon Dalby, Gearóid Ó Tuathail and John Agnew.  It problematizes mainstream geopolitical discourses and examines how they serve power.
Key concepts include practical geopolitics – how states employ geographic assumptions; formal geopolitics – determinist worldviews; popular geopolitics – media representations; and feminist geopolitics. 
Critical geopolitics sees mainstream geopolitics as portraying the world from an elite Western masculinist gaze that silences marginalized groups and reinforces state power. 
For instance, critical analysis shows how the War on Terror narrative framed security in ways that benefited military-industrial interests.  Overall, critical geopolitics politicizes mainstream spatial discourses.
Global Justice Theory
The emergence of the Global Justice Movement has stimulated new theorizing around poverty, global inequality and ethics. 
Key concepts include social justice, fair terms of cooperation, moral cosmopolitanism and the responsibility to protect.  Philosophers like Thomas Pogge and Peter Singer argue for radical reform to global economic institutions and policies that perpetuate severe poverty. 
Feminist scholars articulate concepts like global care chains highlighting uneven burdens.  Activist networks like Attac propose anti-capitalist alternatives like the Tobin tax. 
Critics argue such radical idealism is unrealistic and risks undermining liberal reforms.  Nonetheless, global justice scholarship has ethically reframed development debates.
The English School and World Order Theory
Influenced by the English School, contemporary world order theory analyzes shifting dynamics in the global balance of power and trends in governance. 
Key texts include Henry Kissinger’s World Order, examining different historical conceptions of legitimate world order.  Amitav Acharya analyzes conflicts between western and non-western regional powers over norms and institutions. 
Concepts like multipolarity, BRICS, global governance networks, and rising powers shape debates.  Pragmatic world order theory attempts to synthesize realist, liberal, constructivist and critical insights. 
Critics argue world order theory lacks analytical rigor and predictive capacity.  Nonetheless, it provides a framework for synthesizing broad shifts in the global system.
In conclusion, international relations theory has progressed through vigorous debates over competing concepts like power, institutions, norms and critical perspectives. Diverse analytical frameworks highlight different dimensions of global politics, from material capabilities to social constructs.
Looking forward, twenty-first century challenges like climate change, global inequality and technological disruption will continue reshaping political concepts and debates within the field of international relations.
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