Key Theories of International Relations Explained
Realism in International Relations
Realism is based on three basic ideas shared by all its versions:
- Statism: States are the main players in world politics, not companies or individuals.
- Survival: Every state’s number one priority, always, is to survive.
- Self-help: There is no world police, so every state can only count on itself to stay safe.
Realists also maintain a pessimistic view of human nature, inspired by thinkers such as Thucydides, Machiavelli, and Hobbes.
Classical Realism argues that the problem stems from human nature. Humans naturally desire power, and since states are run by humans, states desire power too, leading to constant competition. Hans Morgenthau’s key idea is simple: in politics, national interest always means power, and that remains constant.
Neorealism (Waltz, 1979) suggests the problem is not humans but the structure of the system. Because there is no world government above states, they are all forced to compete—regardless of who leads them or their type of government. Key concepts include:
- Balancing: Joining forces against the strongest state.
- Bandwagoning: Joining the strongest state instead.
- Buck-passing: Letting someone else deal with a threat.
Waltz argues that bipolarity is the most stable system, while multipolarity is the most dangerous. Mearsheimer disagrees with Waltz on one point: he believes states always try to grab as much power as possible, not just enough to feel safe.
Neoclassical Realism adds another layer: while the structure of the system matters, internal factors—such as a leader’s beliefs, political culture, and domestic institutions—also shape how a state behaves.
The main criticism of Realism is that balancing does not always occur in practice, and focusing exclusively on power overlooks much of what transpires in world politics.
Liberalism and Global Cooperation
Liberalism begins with the same premise as Realism—the international system is anarchic—but reaches a different conclusion: states are not destined for constant conflict, and lasting cooperation is possible under the right conditions.
- Democratic Liberalism: Argues that a state’s government type influences its behavior. The central idea is the Democratic Peace Theory: democracies do not go to war with each other. While evidence supports this, it does not mean democracies fight less in general; they simply do not fight other democracies.
- Commercial Liberalism: Suggests that trade unites countries. High economic interdependence makes war mutually damaging, providing a strong incentive to avoid conflict.
- Liberal Institutionalism: Contends that international organizations—like the UN or the WTO—help maintain peace by sharing information, reducing mistrust, and punishing rule-breakers. Institutions manage anarchy rather than eliminating it.
The main criticism of Liberalism is that it overestimates the power of institutions, which are often run by the most powerful states, and that interdependence can sometimes create conflict rather than prevent it.
Constructivism: The Power of Ideas
Constructivism disagrees with the assumption that states always behave selfishly for power or security. It argues that state behavior depends on beliefs, values, and perceptions of self and others. In other words, ideas matter as much as material power.
The most famous concept in Constructivism comes from Alexander Wendt: “Anarchy is what states make of it.” This means anarchy does not automatically lead to conflict; it depends on interpretation. If states see each other as enemies, they act accordingly; if they see each other as friends, they cooperate.
Constructivism also introduces norms—shared rules about acceptable behavior, such as human rights or sovereignty. These are constructed over time by norm entrepreneurs. Additionally, it distinguishes between the logic of consequences (acting for benefit) and the logic of appropriateness (acting because it is socially right).
The main criticism is the lack of clear evidence that norms and ideas are strong enough to override material interests during critical moments.
Neo-Marxism and World-Systems Theory
Neo-Marxism applies Marxist ideas to International Relations, drawing on authors like Hobson and Lenin. Its biggest departure is that the main actor is the social class, defined by control over the means of production. Economic elites operate globally, competing for resources but cooperating to keep dominated classes under control.
This creates a division of the world into core and periphery: a few rich countries benefit from the system while many poor countries remain disadvantaged. According to Immanuel Wallerstein’s world-systems theory, conflict happens between and within these zones. Global elites influence elections and shape leadership, leading to the conclusion that international competition is a result of capitalism: imperialism.
The proposed solution is a worldwide communist revolution of Trotskyist inspiration. While economic actors clearly influence foreign policy, critics argue there is no clear evidence that social class independently dictates state behavior, as economic and political interests often align.
Critical Theory and Human Emancipation
Originating at the Frankfurt School in 1923, Critical Theory evolved through thinkers like Horkheimer. Its central idea is reflectivism: knowledge and theory are never neutral and always serve some power. This opposes positivism, which seeks objective study.
Applied to International Relations, it is a normative theory aiming to achieve human emancipation by addressing social injustices rooted in the Enlightenment. It serves as the theoretical “mother” of several schools: postcolonialism, feminism, green theory, and postmodernism. Common topics include genocide, failed interventions, and modern slavery.
Postcolonialism and the Global South
Postcolonialism argues that decolonization must be political, material, and cultural. It centers analysis on previously colonized countries and rejects Western-centric perspectives. Former colonies often remain the periphery, serving the Global North through local elites.
Key topics include how imperialism shapes today’s order, Western military presence as neocolonialism, and the emergence of new colonizers from the Global South, such as China. A useful case study for exams is the comparison between “Françafrique” and “Chinafrique” as different forms of neocolonialism.
Feminism and Gender in World Politics
Feminism is both explanatory and normative, seeking to understand and correct gender inequality. It examines how gender influences international politics and vice versa, focusing on victims, gendered structures, and women as active agents of change.
It is categorized into five waves:
- Legal and political equality.
- Socioeconomic and sexual emancipation.
- Social class.
- Intersectionality.
- Redefining womanhood.
Hypotheses include: conflict affects women disproportionately; gender-equal countries are less militaristic; and women negotiators are more effective at achieving cooperation. While it has shown that women improve peacekeeping effectiveness, it remains difficult to empirically demonstrate the impact of gender on major international outcomes due to a lack of leadership data.
Green Theory and Environmental Security
Green Theory examines the relationship between International Relations and environmental degradation through three angles:
- Why states fail to cooperate on environmental issues.
- How degradation affects human security.
- Alternative models of global governance for sustainability.
Main hypotheses include: democracies respect environmental treaties better; climate change creates environmental refugees; and transnational movements have the power to change policy. Climate change serves as the reference case study, often appearing in exams alongside Critical Theory and Feminism.
Eclecticism and Mid-Range Theories
Eclecticism argues that International Relations should focus on solving practical problems rather than defending a single paradigm. It utilizes mid-range theories where causal factors change depending on the case. Its logic is summed up by the phrase “isms are evil.”
Examples include:
- Japan–South Korea relations: Explained by combining Realism (U.S. alliance), Liberalism (economic ties), and Constructivism (historical memory).
- Foreign aid: Effectiveness depends on combined political, cultural, and economic contexts.
While offering analytical flexibility, Eclecticism risks losing the “bigger picture” of world politics by lacking a single coherent framework. Iran is often used as a reference case study for this approach.