Schools of thought
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42 theoretical approaches
Realism States pursue security and power in an international system without a central authority. Liberalism Institutions, economic interdependence and domestic preferences can make sustained cooperation possible. Constructivism International politics is shaped not only by material power, but also by ideas, identities, norms and shared meanings. English School States form an international society when they recognize common interests, rules and institutions despite anarchy. Marxism & Dependency Global politics is structured by capitalism, class relations and unequal patterns of production, exchange and dependency. Feminist IR Global politics is gendered: institutions, security practices and economic orders depend on often-hidden hierarchies and forms of labor. Postcolonialism Colonial histories continue to shape sovereignty, borders, knowledge, hierarchy and whose voices are treated as authoritative. Critical Theory Theories and institutions are never fully neutral; analysis should expose domination and identify possibilities for political emancipation. Neoclassical Realism Systemic pressures influence foreign policy through leaders' perceptions, state capacity and domestic politics. Neoliberal Institutionalism International institutions can sustain cooperation among self-interested states even without a world government. Democratic Peace Theory Established democracies are observed to be unusually unlikely to fight interstate wars against one another. Securitization Theory Political actors can frame an issue as an existential threat and seek acceptance for exceptional security measures. World-Systems Theory Capitalist development forms a world-scale division of labour structured by core, semi-peripheral and peripheral positions. Regional Security Complex Theory Security interdependence often clusters geographically: neighbours' threats and responses are closely linked. Offensive Realism Great powers face incentives to maximize their relative power because they cannot be certain of others' future intentions. Defensive Realism States often obtain security by preserving a workable balance rather than continuously expanding their power. Balance of Threat Theory States form alignments against perceived threats, not necessarily against the materially strongest power. Power Transition Theory War risk may rise when a dissatisfied rising power approaches parity with the dominant state. Hegemonic Stability Theory A leading power may help sustain an open economic order by supporting rules, market access and international public goods. Neofunctionalism Integration in one policy sector can generate pressures for integration in others through spillover and political mobilization. Liberal Intergovernmentalism European integration reflects domestic preference formation, interstate bargaining and choices about credible commitments. International Regime Theory International regimes organize expectations around shared principles, norms, rules and decision-making procedures within particular issue areas. Deterrence Theory An actor attempts to prevent an unwanted action by credibly communicating costs or denial of benefits. Strategic Culture Historically shaped beliefs, symbols and practices can influence how security elites understand and use military force. Critical Geopolitics Geographical descriptions and maps are not neutral: political actors produce spatial narratives that justify foreign-policy choices. Security Community Theory Shared identities, institutions and dependable expectations of peaceful change can make war among members increasingly unlikely. Two-Level Games International bargaining takes place simultaneously at the negotiating table and within domestic constituencies that must accept its outcome. Bureaucratic Politics Model Foreign-policy outcomes may emerge from bargaining among officials and organizations with different responsibilities and interests rather than a unitary national decision. Prospect Theory Decision-makers evaluate risky options relative to perceived gains and losses rather than absolute outcomes, potentially producing different risk choices across contexts. Role Theory in Foreign Policy Leaders' conceptions of the roles their country should play can shape foreign-policy commitments, while external expectations may reinforce or challenge those roles. Postfunctionalism European integration is increasingly shaped by politicization, mass identity and party competition rather than elite agreement alone. Multi-Level Governance Authority and policy-making in the EU are distributed across supranational, national and subnational institutions rather than monopolized by national governments. Bargaining Theory of War War can occur despite mutually preferable peaceful bargains because private information, commitment problems or indivisible demands obstruct agreement. Weaponized Interdependence States occupying central positions in asymmetric financial and information networks may obtain surveillance and exclusion advantages over others. Ontological Security Theory Political actors may seek continuity in their self-identity and routines even when familiar practices expose them to material security risks. Historical Institutionalism Institutions and policies evolve along historically established paths, so timing, sequences and critical junctures help explain later outcomes. Principal-Agent Theory Delegating authority to an agent can create information asymmetries and opportunities for independent action beyond what the principal intended. Practice Theory in International Relations International politics is enacted through recurring competent practices, embodied know-how and the shared understandings of diplomatic and security communities. Regime Complexity Overlapping international agreements and organizations in the same issue area can generate competing rules, strategic forum choices and fragmented authority. Green Theory International relations should account for ecological limits, nonhuman nature and environmental justice rather than treating growth and state interests as unquestioned goals. Global International Relations (Global IR) International relations scholarship should incorporate histories, experiences and theoretical contributions from beyond its traditionally Eurocentric canon. Poststructuralism in International Relations Political language and representational practices help constitute the identities, threats and boundaries through which international affairs are understood.
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Key thinkers Thucydides Niccolò Machiavelli Hans Morgenthau Kenneth Waltz John Mearsheimer
Core assumptions 1 The international system is anarchic: no supreme authority stands above sovereign states.
2 States are the principal actors in international politics and must provide for their own survival.
3 Power-especially material and military capability-shapes bargaining, deterrence and conflict.
4 Uncertainty about other states' intentions encourages caution, competition and balancing.
5 Cooperation is possible, but it is constrained by security concerns and relative gains.
Foundational works History of the Peloponnesian War
Thucydides
Politics Among Nations
Hans Morgenthau · 1948
Theory of International Politics
Kenneth Waltz · 1979
The Tragedy of Great Power Politics
John Mearsheimer · 2001
Key concepts What does it explain best?
Explaining rivalry, alliance formation, deterrence, arms races and great-power competition.
Critical perspectives Realism is often criticized for treating state interests as too fixed, underestimating institutions and domestic politics, and struggling to explain durable cooperation or major changes in identity and norms.
