Four ways of understanding why states behave the way they do. Realism, liberalism, the English School, and constructivism - the analytical lenses you need to deploy in every Paper 3 Global essay, tested against the war in Ukraine.
When examiners ask why states cooperate, why they go to war, why the European Union exists and why the UN does not work, they are asking you to use a theoretical lens. International relations is not just a chronicle of events - it is a discipline that argues about why those events happened. Four major theoretical traditions dominate the field and dominate Edexcel A-level Global Politics. Realism says states are billiard balls in anarchy, pursuing their own survival. Liberalism says states can cooperate through institutions and mutual interest. The English School says there is more order in international politics than realists admit, because states share norms and rules. Constructivism says identity and ideas shape what states want in the first place. Each theory is a way of seeing the world. The strongest A-level answers deploy them as analytical tools, not as facts to be recited.
Why theory matters before any specific question.
International relations theory is not abstract decoration. Every claim about why a state did something rests on some theoretical assumption. When a commentator says "Russia invaded Ukraine to protect its security interests", they are making a realist claim. When another says "Russia invaded because it had become an autocracy that no longer accepts the post-1991 European liberal order", they are making a constructivist or liberal claim. When a third says "the EU sanctions show that there is a society of states that punishes rule-breakers", they are making an English School claim. The interpretation comes BEFORE the conclusion.
Edexcel expects A-level Global Politics candidates to know four theoretical traditions and to apply them to substantive questions. The strongest answers do not just describe the theories - they deploy them as competing readings of contemporary events. A 30-mark essay on the war in Ukraine should not pick one theory and ignore the others. It should compare what each theory says, identify where they agree and disagree, and reach a clear judgement on which best explains the case.
The dominant tradition of the modern era. Scroll through its key claims.
States are the dominant actors. They operate in anarchy. They pursue national interest defined primarily as security and power. They cannot trust other states because there is no enforcement of agreements above them. Cooperation is possible but limited and contingent on power balance. War is a recurring feature of the system. Scroll through the variants.
Hans Morgenthau, Politics Among Nations (1948), is the foundational text. Classical realism roots state behaviour in human nature - states are run by humans, humans are driven by lust for power and self-preservation, so states pursue power and self-preservation. Morgenthau's six principles include: politics is governed by objective laws rooted in human nature; statesmen think in terms of interest defined as power; the concept of interest is universal but its content is historically variable. Classical realism builds on a Hobbesian view of human nature - life in the state of nature is "nasty, brutish, and short", and so is life in international anarchy.
Kenneth Waltz, Theory of International Politics (1979), is the modern foundation. Waltz argued classical realism was wrong to root state behaviour in human nature. The real driver is structure: states behave the way they do because they exist in an anarchic system without an overarching authority. Any state, regardless of its government type or culture, would behave similarly in that structure. Neo-realism predicts that great powers balance against the most powerful state to prevent dominance. The Cold War (USSR balancing the US) and now the rise of China balancing the US are the canonical examples.
John Mearsheimer, The Tragedy of Great Power Politics (2001), is the contemporary hard-edged variant. Mearsheimer argues that states do not just seek security - they seek hegemony. Because states can never be certain of others' intentions, the rational strategy is to accumulate as much power as possible, ideally to become the most powerful state in the region. Mearsheimer is the most prominent contemporary realist commentator on Russia and Ukraine - he has argued for over a decade that NATO expansion eastward would provoke a Russian backlash. Critics see this as apologetic for Putin; defenders see it as analytical realism.
The internal counter-tradition to Mearsheimer. Defensive realists argue that states seek security NOT hegemony - the costs of seeking hegemony usually exceed the benefits, because other states balance against the would-be hegemon. The Iraq War 2003 is the defensive-realist case study: the US sought hegemonic intervention and paid a strategic cost. Security dilemma is a defensive-realist concept: state A's defensive measures look offensive to state B, which increases its own forces, which then looks offensive to A. Mutual fear produces conflict even when neither side wants it.
Realism does poorly on: the EU (deep cooperation among states that should be rivals); international institutions that constrain great powers (WTO, ICJ); the role of non-state actors (multinationals, NGOs, terrorist groups); the long peace among democracies; major moral norms (slavery prohibition, human rights, R2P). Realists usually respond that these are anomalies, marginal cases, or the products of underlying power. Critics argue realism's predictions consistently fail in these domains.
The counter-tradition. Scroll its main claims.
States are NOT the only actors - international institutions, NGOs, multinational corporations all shape outcomes. Anarchy does not prevent cooperation - states can build institutions that bind themselves. Trade interdependence reduces the incentive for war. Democracies do not fight each other. The international order is improvable through law, trade, and democratic spread.
The classical foundation is Immanuel Kant's essay Perpetual Peace (1795), which argued that war would diminish if states became republics (responsive to their own citizens, who bear the costs of war) and built a federation of free states. Modern liberal internationalism descends from this. The post-1945 institutional order - UN, IMF, World Bank, GATT then WTO, regional bodies, NATO - is the liberal-internationalist project in practice. The argument: institutions create rules, predictability, and lower transaction costs of cooperation.
Robert Keohane and Joseph Nye, Power and Interdependence (1977), is the modern liberal foundation. Their argument: in the contemporary world, states are tied together by multiple channels (economic, social, environmental, technological) that make traditional realist categories misleading. Military force is less central; economic interdependence matters more. States face a complex web of mutual sensitivities and vulnerabilities. Russia-Europe gas dependence before 2022 is the textbook case of complex interdependence working in both directions.
Michael Doyle's 1983 essays revived Kant's argument with empirical data: democracies do not fight wars with each other. The pattern is one of the most well-established findings in IR. There are debates about why (shared norms, structural constraints, transparency reducing security dilemmas) but the empirical pattern itself is unusually strong. Implication: the spread of democracy is itself a peace-building project. The post-1990 expansion of liberal democracies in Eastern Europe is the empirical test case - and its partial reversal since 2010 (Hungary, Turkey, India backsliding) is the contemporary worry.
The most influential modern liberal variant, also Keohane. Argument: even in anarchy, states have repeated interactions that make cooperation rational. Institutions reduce transaction costs, build reputation effects, monitor compliance, and create iterated games that punish defection. The WTO dispute-settlement system, the EU's deep integration, NATO's persistence after the Cold War, the Paris Climate Agreement's ratchet mechanism are all institutional arrangements that constrain great powers more than realism would predict.
Liberalism does poorly on: outright power competition between great powers (the US-China contest); cases where institutions fail to constrain great powers (Russia in Ukraine; Israel-Gaza); the resilience of authoritarian regimes that should not exist according to democratic-peace logic; the partial reversal of democratisation since 2010. Critics argue liberalism describes the post-Cold-War unipolar moment when US dominance made institutional cooperation easy - and that the return of multipolarity is exposing liberalism's optimism as conditional on US power.
The British alternative. Order in anarchy through shared norms.
Founded at the London School of Economics in the 1960s, most associated with Hedley Bull's The Anarchical Society (1977). Argument: international politics is anarchical (no overarching authority) but it is also a society - states share norms, rules, institutions, and a sense of common interests. This makes it different from a Hobbesian state of nature and different from a domestic society. International order is real but rests on consent and shared understanding.
The core English School concept. States are not just billiard balls colliding in anarchy. They share rules of sovereignty, diplomacy, non-intervention, recognition of borders, conduct of war. These are not external impositions but mutually recognised norms. The society of states is what makes diplomacy possible. Bull identified five institutions of this society: balance of power, international law, diplomacy, war (as a regulated practice), great-power management. The order is not perfect - states violate the norms - but the norms themselves shape behaviour.
The classical English School position. The international society is pluralist - states agree on a thin set of rules (sovereignty, non-intervention) but disagree on substantive values (human rights, religious freedom, economic system). Pluralism respects that disagreement; it does not try to impose one state's values on another. Non-intervention is the bedrock principle. The Westphalian framework is the pluralist achievement: a way for diverse polities to coexist.
The contemporary English School development. Solidarism argues that the international society has thickened - states now share more substantive norms, particularly around human rights, genocide prevention, and the responsibility to protect (R2P, endorsed at the UN 2005 World Summit). Where pluralism says non-intervention is the bedrock, solidarism says non-intervention can be overridden when states fail their citizens systematically. Libya 2011 (UNSC-authorised intervention) was the high point of solidarist practice. The retreat since (Syria, Yemen, Ukraine, Myanmar) is the pluralist counter-narrative.
The English School is the most empirically subtle of the IR theories - it accepts realist insights about anarchy while also explaining the institutional richness liberals describe. It also handles the variation between regions well - the international society is thicker in Europe, thinner in the Indo-Pacific. The limits: critics argue solidarism overstates the depth of normative consensus; the post-2014 return to great-power confrontation has eroded the society's shared rules; the English School's focus on states underweighs non-state actors and economic globalisation.
The newest tradition. Scroll through its central claims.
States' interests and identities are not fixed by the structure of anarchy. They are shaped by ideas, norms, identity, and history. The same structural condition can produce different state behaviours depending on what states believe about themselves and others. Anarchy is what states make of it. Scroll through the variants.
Alexander Wendt's 1992 essay - one of the most-cited articles in modern IR - is the foundational text. Wendt accepts the realist premise of anarchy but argues anarchy does not have a single meaning. States interpret the structure through their identities and ideas. Three "cultures of anarchy" are possible: Hobbesian (enemies), Lockean (rivals), Kantian (friends). Which culture predominates depends on what states have come to believe about each other. Western Europe shifted from Hobbesian (1914-45) to Lockean (Cold War) to largely Kantian (post-1989) - a structural change driven by ideational change.
Constructivists argue that what states want (interests) flows from who they think they are (identity). Germany after 1945 built an identity around being NOT the militarist Germany - and this identity shaped its post-war pacifism, EU commitment, and reluctance to use force. The 2022 Zeitenwende (Chancellor Scholz's announcement of major rearmament after Russia invaded Ukraine) was a major identity shift. Japan's post-war pacifism is similar. Constructivists argue that realism cannot explain these patterns because realism has no place for identity-driven behaviour.
Constructivists study how international norms spread and become taken for granted. Martha Finnemore and Kathryn Sikkink's work on "norm cascades" describes how a critical mass of states adopting a norm produces wider adoption. The norm against chemical weapons use (Chemical Weapons Convention 1993 onwards) is a textbook case - violations are rare because the norm has cascaded. The norm against landmines (Ottawa Treaty 1997) is another. The retreat of certain norms (torture after 9/11; territorial conquest with Russia in Ukraine) is also constructivist-relevant - norms can erode as well as cascade.
The more radical constructivist variants question whether IR is a science of objective discovery or itself a social practice that produces what it claims to describe. Realism's claims about anarchy, on this view, are not neutral descriptions but ideological frameworks that justify particular kinds of state behaviour (military spending, balance-of-power politics). These post-positivist constructivists are often radical critics of mainstream IR; they overlap with feminist IR, postcolonial IR, and post-structuralism.
Constructivism does best on long-term change - explaining how norms emerge, evolve, and decay over decades. It does less well on immediate strategic decisions where realist calculations of power are unavoidable. Critics also note that constructivism can struggle to predict - it tends to explain after the fact. The strongest constructivist work usually accepts realist constraints and shows how ideas operate within them, rather than treating ideas as primary drivers.
How each theory reads the same event.
The Russia-Ukraine war that began in February 2022 is the contemporary test case for IR theory. Each theory reads it differently. The strongest A-level answers use this kind of multi-lens analysis - showing that the same event yields different conclusions depending on the theoretical framework deployed.
Realism, liberalism, the English School, constructivism. Each reads the war differently. Scroll through.
Russia invaded Ukraine for security reasons - NATO expansion eastward threatened Russian security and great-power status. Mearsheimer has argued this case since at least 2014. Western support for Ukraine is balance-of-power behaviour - the US and Europe preventing Russian regional dominance. The war continues because neither side has accepted the strategic facts: Russia cannot afford to lose; the West cannot afford to let Russia win. A realist solution is a negotiated settlement that recognises Russian sphere of influence concerns. Critics see this as apologetic for aggression.
Russia invaded a democracy. The post-1991 European liberal order, built on institutions and norms, did not deter the invasion - but the sanctions response and Ukrainian resistance demonstrate that institutions and democratic solidarity matter. EU enlargement, NATO support, IMF financing of Ukraine all reflect liberal-institutional commitments. The war is testing whether the liberal order can hold against authoritarian revisionism. Democratic peace theory: a democratic Russia would not have invaded.
Russia violated the bedrock norm of the society of states: non-aggression against a sovereign state. The international response (sanctions, ICC indictment of Putin for war crimes, UN General Assembly votes) demonstrates the society of states punishing a rule-breaker. The non-Western response (China abstention, Global South neutrality) demonstrates that the society of states is not uniformly thick - non-intervention norms hold in most regions, but solidarist responses (sanctions, military aid) are largely a Western project. The war is testing pluralism's limits.
Russia invaded because of identity, not just security. Putin's identity as the leader of a great power humiliated by the Cold War's end produced the invasion. Ukrainian identity-formation since 2014 (the Revolution of Dignity, EU aspirations, language and church reorganisation away from Moscow) was experienced in Russia as identity-loss. The German Zeitenwende after 2022 is also constructivist - a major shift in German military identity. Norm erosion: territorial conquest had become unthinkable in Europe since 1945; the invasion attacks that norm.
The strongest readings of the war in Ukraine use multiple lenses simultaneously. Realism explains the strategic logic and the limits of negotiated outcomes. Liberalism explains the institutional response and the role of Ukrainian democratisation. The English School explains the global pattern of responses and the divide between Western and non-Western reactions. Constructivism explains why Russia chose this moment and why the invasion is so personally tied to Putin. A 30-mark answer that uses one lens is partial; the strongest answers explicitly compare them.
Likely 30-mark questions and the three-theme structure.
The architecture of every 30-marker on IR theory. Questions usually ask you to evaluate one theory against another, or to apply a theory to a contemporary case. The strongest answers use multiple theories as competing lenses on the same evidence.
Trap: "remains" implies historical comparison. Three themes: realism's strength on great-power competition (Ukraine, US-China, sanctions); liberalism's strength on institutional cooperation and democratic peace; constructivism's strength on identity-driven decisions. Argue realism best explains some domains, others best explained by liberalism or constructivism - no single theory is the most useful for everything.
Trap: "better than" forces a comparison. Three themes: institutional successes (WTO, EU, Paris ratchet); institutional failures (UNSC paralysis on Ukraine, Israel-Gaza); the conditional nature of institutions (most institutions reflect US power; their resilience depends on continuing US commitment). Argue liberalism explains cooperation under unipolarity; realism returns under multipolarity.
Trap: "best explanation" forces a comparison. Three themes: identity-driven shifts (Germany's Zeitenwende; Putin's identity politics); norm cascades (chemical weapons, landmines); but realist counter-cases where strategic calculation dominates (Iraq War 2003 decision; Ukraine military operations). Argue constructivism explains shifts that realism cannot, but does not replace realism on immediate strategic decisions.
Trap: "remains relevant" implies a contemporary test. Three themes: society-of-states norms (non-aggression, sovereignty, diplomacy still operative); solidarist developments (R2P, ICC, human rights enforcement); but post-2014 great-power confrontation eroding the shared rules. Argue the society of states is real but thinner than 1990s liberal optimism suggested.
Three directly comparative themes.
Anarchy - the absence of an overarching authority above states. Not chaos; the structural condition of the international system.
Realism - the IR tradition that emphasises states, anarchy, national interest defined as security and power.
Classical realism (Morgenthau) - roots state behaviour in human nature; Hobbesian inheritance.
Neo-realism / structural realism (Waltz) - roots state behaviour in the structure of anarchy; all states behave similarly under it.
Offensive realism (Mearsheimer) - states seek hegemony, not just security.
Defensive realism - states seek security; balancing punishes hegemony-seekers.
Security dilemma - state A's defensive measures look offensive to state B, producing mutual fear and arms-racing.
Liberalism - the IR tradition that emphasises institutions, interdependence, democracy, and the improvability of international politics.
Liberal internationalism - the Kant lineage; post-1945 institutional order; UN, IMF, WTO etc.
Complex interdependence (Keohane and Nye) - multiple channels of mutual sensitivity between states; military force less central.
Democratic peace theory (Doyle) - democracies do not fight wars with each other; an empirically well-established pattern.
Neoliberal institutionalism - institutions reduce transaction costs and make cooperation rational in anarchy.
English School - the British IR tradition emphasising the society of states - shared rules, norms, institutions among states despite anarchy.
Society of states (Hedley Bull) - states share five institutions: balance of power, international law, diplomacy, war, great-power management.
Pluralism (English School) - states agree on thin rules (sovereignty, non-intervention) and disagree on substantive values.
Solidarism (English School) - international society has thickened to include human rights, R2P; non-intervention can be overridden in extreme cases.
R2P (Responsibility to Protect) - 2005 UN World Summit doctrine; states have a responsibility to protect their citizens; the international community can intervene when they fail.
Constructivism - the IR tradition that emphasises ideas, identity, and norms as drivers of state behaviour.
Wendt's three cultures of anarchy - Hobbesian (enemies), Lockean (rivals), Kantian (friends). Which culture predominates depends on what states believe about each other.
Norm cascade (Finnemore and Sikkink) - the process by which an international norm spreads from early adopters to wider acceptance.