Theories of International Relations: Realism, Liberalism, Constructivism (2023)

Theories of international relations help us better comprehend how international systems function and also how states interact with one another and perceive global aspects. Diplomatic officials and international relations scholars frequently employ international relations theories, which range from liberal, justice-based approaches to simple realist notions, to determine the path that a nation should take concerning an international political issue or situation. Professionals in the discipline could further understand the motives and aims that underlie policy choices around the planet by examining the relevant major international theories. The theories discussed ahead are the major theories of international relations and that form the foundation of many other theories in this discipline such as the bargain theory, feminist theory, and balance of power theory. Each of the following major theories includes different parts of international relations, unlike the derived theories which are specific to the sub-fields like international trade, law among others.

Theories of International Relations: Realism, Liberalism, Constructivism (1)

  1. Realism

Developed in the early 20th century, Realism is a simple perspective of state-centred international affairs, which claims that all states are attempting to enhance their power and that those governments who can efficiently accumulate such strength will prosper, quickly transcending the accomplishments of comparatively less compelling states. According to this theory’s assumption, a nation’s primary goal ought to be self-preservation, and increasing power has to be a socioeconomic and political requisite. Based on different assumptions, realism has evolved and diversified in the realm of international relations as structural defensive realism, offensive realism, and many others. Glenn H Snyder remarked on this diversity: “the field of international relations now has at least two varieties of structural realism, probably three kinds of offensive realism and several types of defensive realism; in addition to neoclassical, contingent, specific and generalist realism” (as cited in Chatterjee, 2011).

  • Defensive Realism

Kenneth Waltz’s defensive realism bases the struggle for power as a defensive strategy in the anarchy structure of the international system. Waltz states, “Internationally, the environment of states’ actions, or the structure of their system, is set by the fact that some states prefer survival over other ends obtainable in the short run and act with relative efficiency to achieve that end” (Waltz, 1979). According to this, states tend to act in favour of a balance of power instead of letting other states develop economically, military strengths, and political power because it is perceived as a threat to their security and interests. According to defensive realism, nations should obtain the proper measure of power to enable them to survive. They should not, nevertheless, use their comparative power to try to become hegemonic powers.

Example: During the Cold war, the U.S. and the U.S.S.R were in a nuclear arms race which was the result of the nations’ attempting to secure their own nation against the other. As seen in the Cuban missile crisis, the U.S. was involved in a blockade of Cuba as it was seeking to ensure the survival of its territories against the Soviet missile and, similarly, the Soviet Union was in an attempt to secure itself against the U.S. missiles in Turkey. Therefore, both parties were engaged in a struggle to defend themselves while hindering the military progress of their counterparts

  • Offensive Realism

Offensive realism, on the other hand, is more convinced by anarchy’s structural potential for creating conflict. With no authority to impose accords, proponents of this perspective maintain that governments can never be sure that whatever peace-making conditions in existence currently will be in effect in the future too. Given such ambiguity, nations may seldom be convinced of their security and must continually be suspicious of other states’ growing strength. According to offensive realism, nations are prone to rivalry and conflict because they are self-interested, power-maximizing, and frightened of other states. Furthermore, it contends that nations are obligated to behave in this manner in order to survive in the international system. John Mearsheimer argues that the international system requires that states maximize their offensive power to be secure and keep rivals from gaining power at their expense. (Mearsheimer, 2001).

(Video) Major Theories of IR

Example: Historically, there have been multiple attempts by nations to become a hegemon through aggressive strategies. One of the major reasons for World War II was Nazi Germany’s venture to establish absolute post-war continental hegemony of Nazi Germany. And it was supposed to be accomplished by expanding the German state’s geographical territory by aggressive action, along with the political and economic subordination of the European countries to Germany. The underlying objective of this was to secure the interests of German Nazis against others.

2. Liberalism

Liberalism is centred on the premise that the existing international system is competent in establishing a harmonious global order. Instead of depending on aggressive force, such as military conflict, liberalism encourages global cooperation as a tool of advancing every state’s individual goals. Liberalists think that the negative repercussions of using warfare, such as economic damage and civilian fatalities, considerably outweigh the possible gains. As a result, liberal political leaders normally like to use economic and political power to realize national objectives. In the current, globally connected world, economic techniques such as bilateral agreements and international political diplomacy might be more efficient than using force in achieving political objectives. Realism might have begun to fade as a credible political approach as liberalism has grown to be more established in international collaboration via the formation of organisations such as the United Nations. It may also be suggested that the liberalist tradition, as sustained by the US, is becoming the predominant framework in international relations, with defined principles and international bodies in place to govern this system. Supranational governance research, particularly on the link between democracy and global collaboration, is prospering, and it supports liberal studies on democratic peace-making.

Example: The SAARC Preferential Trading Arrangement (SAPTA) represented the Member States’ intention to enhance and sustain mutual trade and economic cooperation within the SAARC area via the exchanging of tariff concessions (Dep of Commerce, Sri Lanka). The notion of liberalising commerce among SAARC states led to the conception of SAPTA as the first step toward the establishment of a South Asian Free Trade Area (SAFTA), which would eventually lead to a Customs Union. This encourages economic cooperation among governments rather than war.

  • Constructivism

Constructivism theories in international affairs are based on the assumption that nations, like humans, exist in a world of our making in which certain concepts, such as social facts, gender roles are created by human activity, as opposed to brute facts, which are developed independently (Onuf, 1989). Its arguments are based on concepts such as discourses, conventions, identities, and social interaction, which are widely used in contemporary conversations about a variety of international matters such as globalization, international human rights, defence policy, and others. Constructivism believes that the structure of the international system cannot be uniformly applied to all state relations as it mainly bases the relations and interactions between countries and their shared understandings as the sources of conflicts or cooperation. Constructivists view identity as the basis for interests, institutions, and relations between countries. Wendt argues that states are “intentional and corporate actors whose identities and interests are in important part determined by domestic politics rather than the international system,” (1999) and this denotes that these actors’ policies and actions affect the international structure directly or indirectly.

Example: The nations India and Pakistan were built on ideological and religious grounds that were directly opposed. The core issue of these antagonisms has expressed itself in a ‘Self-and-Other’ rivalry, with both states challenging the authenticity of the other. The conflicting religious identities of India and Pakistan are a primary cause of continuing conflicts. The rivalry between them could further escalate as Hindu nationalism as a national identity is growing in India. The domestic politics of both states influences and is influenced by the religious identity of their citizens and therefore affects the relationship between the two countries. The military strategies of the two countries are based on the notion that the identity of the other is conflicting and therefore a threat.

(Video) Realism vs. Liberalism - Global Politics Theories Compared


The international system is filled with interactions among states as well as non-state actors. These interactions are of various types and the theories of international relations are an attempt to understand them and use them to analyze and predict decisions. The theories evolve with time and space, providing multiple perspectives and approaches to viewing situations. It is to be noted that the interactions between nations do not belong to one major theory as there can be hybrid theorizations of nations that cover different aspects of the actors’ relations and, therefore, theories in international relations are often debated among scholars. However, despite its complex network of approaches, the theories have made great progress and continue to do so, in analyzing the relations of various types in the world today.

Also Read: Resource-Based Conflicts


Johnson, D., & Thayer, B. (2016). The evolution of offensive realism: Survival under anarchy from the Pleistocene to the present.Politics and the Life Sciences,35(1), 1-26. doi:10.1017/pls.2016.6

Snyder, G. (2002). Mearsheimer’s World-Offensive Realism and the Struggle for Security: A Review Essay. International Security, 27(1), 149-173.

(Video) Lecture 2- Theories of International Relations: Realism, Liberalism and Constructivism

Badie, B., Schlosser, D. (2011). Liberalism in International Relations. International Encyclopaedia of Political Science. Sage.

NA. (2017). Key Theories of International Relations. Norwich University.

NA. Department of Commerce, Sri Lanka.

Chatterjee, S. (2011). Structural realism and South Asian security. In Sridharan, E.,International relationstheoryand south Asia(pp. 35-70). Oxford.

Onuf, N.G. (1989).World of our making: Rules and rule in social theory and international relations.University of South California Press

Waltz, K. (1979).Theory of International Politics.Addison-Wesley Publishing Company.


Wendt, A. (1999).Wendt,Social Theory of International Politics. Cambridge University Press.

Checkel, J. T. (2008). Constructivism and foreign policy. In Smith, S. Hadfield, A. & Dunne, T.,Foreign Policy: Theories. Actors. Cases. Oxford University Press. DOI:10.1093/hepl/9780198708902.003.0004

Mearsheimer, J. J. (2001).The tragedy of great power politics. WW Norton.

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What are the 3 main IR theories? ›

This article identifies Realism, Liberalism, and Constructivism as the three major branches of IR theory. These three branches have replaced the earlier realism-idealism dichotomy.

What is realism liberalism and constructivism? ›

Whereas realism deals mainly with security and material power, and liberalism looks primarily at economic interdependence and domestic-level factors, constructivism most concerns itself with the role of ideas in shaping the international system; indeed it is possible there is some overlap between constructivism and ...

What are the 5 IR theories? ›

The five main theories of international relations include: realism theory, liberalism theory, Marxism theory, constructivism theory, and feminism theory.

What is the theory of liberalism? ›

Liberalism is a political and moral philosophy based on the rights of the individual, liberty, consent of the governed and equality before the law.

What are the types of international relations? ›

International relations, world politics, transnational relations, global society. This sphere of diplomacy and war, treaties and alliances, aid and trade, migration and tourists. This arena of empires, international organizations, states, nations, governments, groups and individuals.

What are the theories of constructivism? ›

Constructivism is the theory that says learners construct knowledge rather than just passively take in information. As people experience the world and reflect upon those experiences, they build their own representations and incorporate new information into their pre-existing knowledge (schemas).

What is constructivism theory in IR? ›

In international relations, constructivism is a social theory that asserts that significant aspects of international relations are shaped by ideational factors (which are historically and socially constructed), not simply material factors.

What are examples of constructivism? ›

Example: An elementary school teacher presents a class problem to measure the length of the "Mayflower." Rather than starting the problem by introducing the ruler, the teacher allows students to reflect and to construct their own methods of measurement.

Which international relations theory is best? ›

The realist theory concentrates on few major assumptions and uses those to better cope with international politics, which is certainly an advantage over other theories when describing today's world.

Which is better realism or liberalism? ›

While liberalism offers an optimistic view of the global order, it's more about what the world ought to be. Realism is more about what the world is. For realists, a peaceful global order is desirable, but that's far from reality. Hence, they are pessimists.

What are the basic differences between realism and liberalism? ›

While realism is taken to portray pessimism in the relations between states in the international system, liberalism depicts optimism and positivism in as far as the relations and goals of states in the international system are concerned. Realism depicts competition in the relations between states.

Which IR theory is the best? ›

First, realism is the easiest way to approach international politics and describing the world. Second, realism best applies to our daily individual lives and, therefore, dominates how we shape international relations.

What is system theory in international relations? ›

Systems theories of international relations (IR) focus on the structure of the international system to explain the behavior and interactions of the system's units. The units consist primarily of states, which collectively constitute a system of states.

Which is better realism or liberalism? ›

While liberalism offers an optimistic view of the global order, it's more about what the world ought to be. Realism is more about what the world is. For realists, a peaceful global order is desirable, but that's far from reality. Hence, they are pessimists.

What is liberalism theory in international relations? ›

October 2nd, 2017. Liberalism is a social school of thought in international relations theory that developed in the 1970s. The political concept holds that the state is not subject to external authority of other states nor is it subject to other internal authorities such as the military.


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