Power & Market

Realism, Liberalism, and Constructivism: A Primer on International Relations Theory

University of Chicago professor John Mearsheimer gave a lecture to a group of university alumni in 2014 entitled “Why is Ukraine the West’s Fault,” essentially predicting the Russo-Ukrainian war. The lecture has over 24 million views. Even though he’s been accused of pro-Putin sympathies, Mearsheimer approached the topic of NATO encroachment and Russian security concerns from a dispassionate perspective, using international relations theory to see the situation from the Russian side. 

Much how Misesians search for the “regularity in the concatenation and succession of events,” international relations theory tries to observe regularities in the way states behave. By understanding the operation of the international system of states, strategists and policymakers can generalize and hopefully predict global events, like incursions. Just like in economics, theory models empirical reality. For IR scholars, that reality is the relationships among states in the international system. Ultimately, the field of international relations offers three broad lenses through which observers can view the world: realism, liberalism, and constructivism.


John Mearsheimer is among the foremost experts in international relations who view the world through a realist lens. Realism focuses on the absence of an overarching global government that can harness the behavior of state and non-state actors. In other words, the world lives under a state of international anarchy. As a result, states pursue security above other concerns. Distrust of other states means that they can only truly rely on themselves to protect their national interests, a principle known as self-help.

Thucydides’ History of the Peloponnesian War in the fifth century BCE first formulated the basic assumptions of realism. First, the state is the primary actor in international politics. Second, the state is a unitary actor. Third, the state is a rational actor: it weighs costs and benefits, seeking to maximize utility in the decisions it makes. Fourth, the state focuses on security from both foreign and domestic threats. To the methodological individualist, these assumptions that states take on the characteristics of subjective and acting human beings seem exaggerated. As the state can be defined as that institution that enjoys the monopoly on the legitimate use of violence within a given territory, it stands to reason that states would also project that violence outward in the name of self-preservation.

Hans Morgenthau and Kenneth Waltz applied realism to the modern international state system, which began after the Peace of Westphalia in 1648. Morgenthau (1948) argued that states struggle against each other for both military and economic power, leading to an acute focus on relative—rather than absolute—gains compared to other states. A feature of this struggle for relative gains is the security dilemma, a situation in which one country responds to an increase in the capabilities of another country with a counter increase in capabilities. A tit-for-tat increase in capabilities ensues, leading all sides into a state of tension where no side has an incentive to back down.

Kenneth Waltz (1979) developed neorealism, also known as structural realism, positing that the structure of the international system explains international politics better than any inherent and universal characteristic of states. His Theory of International Politics theorizes that the distribution of power in the world determines peace and war. In particular, the world can be unipolar, bipolar, or multipolar. Bipolarity and multipolarity represent more distributed balances of power than the current “unipolar moment” that the United States enjoys today. It is an open question—and one that theorists actively debate over—whether unipolarity, bipolarity, or multipolarity leads to greater global peace.


Liberalism states are more cooperative, challenging the realist assumption that states are primarily in conflict with one another. Through trade, treaties, norms, diplomacy, and international institutions, states emphasize peaceful transaction over zero-sum power projection. Although this IR theory of liberalism derives from Enlightenment thinkers, it is not a prescriptive ideology like classical liberalism. Remember that IR theories try to formulate a generalized model about how states operate in the international system. Accordingly, IR liberalism views states as rational individuals are, cooperating and transacting for mutual benefit. 

Mutual benefits can accrue when states create institutions to enforce rules that govern behavior, to allow states to communicate, and to mediate disputes. Collective security arrangements provide security guarantees to member states if one should be aggressed against by an outside actor. This collective defense provides an initial deterrent to would-be aggressors. Likewise, liberals do not ignore security as a concern. Rather, they see cooperation as an observable way that states reckon with international anarchy.

A modern variant of liberalism is neoliberal institutionalism, which argues that states cooperate most of the time through what Robert Keohane and Joseph Nye (1977) termed complex interdependence. States interact through multiple channels, in addition to formal diplomacy, and have a range of issues through which agreement can be derived. Military force then moves increasingly farther down the preference scale of states the more they interact and depend on each other. Repeated interaction among states helps them find common interests and reduces their incentive to exploit each other’s weaknesses through military force. International governmental organizations, or IGOs, facilitate these interactions to generate mutual benefit.


A third and less unified theory of international relations called constructivism focuses on norms and identities for explanations of global politics. States derive their identities from individuals, cultures, and norms and thus view international anarchy to be interpreted differently by each state. Consequently, states with opposing identities might have divergent interests in international politics.

Alexander Wendt (1992) stated that “anarchy is what states make of it,” expressing the common postmodernist critique of reality as being socially constructed. States view the world in terms of their elites’ beliefs, identities, and social norms. Where realists will point to states as being primarily security-oriented, constructivists will counter that security, and national interests for that matter, has no single objective meaning that can be applied to all states. In addition, what constitutes as an identity or norm evolves over time, rendering blanket assumptions of state behavior inert.

The power of ideas is important to constructivists. Diffusion of ideas, culture, and language through internationalization, socialization, or hybridity become ways in which identities can be shaped. Constructivism does not contribute an overarching theory about states, as realism and liberalism attempt to do, and it is often thought to be more of a critical theory like Marxism or feminism. Its value in interpreting international politics is in recommending to analysts that they should study the individual cultures, histories, values, and norms each country carries with it to the international scene.

Applying These Perspectives to the Real World

The most visible international event currently is the Russo-Ukrainian War. Russia was powerless to halt the NATO enlargements of 1999 and 2004, which incorporated many of the former Soviet and Soviet-bloc countries of Eastern Europe and the Baltic Sea coast. NATO moved into Russia’s historical sphere of influence and abutted Russia’s western border. NATO sought further encroachment: in 2008, it declared its support for eventual Georgian and Ukrainian accession to the alliance. Vladimir Putin pushed back, calling it a direct threat to Russia. Like NATO, the European Union simultaneously sought eastern integration with its Eastern Partnership proposal to bring Ukraine gradually into its economic orbit. 

Ukrainian domestic politics further exacerbated the tensions. American-backed protests in 2014 culminated in the ouster of Ukrainian president Viktor Yanukovych and the installing of a pro-Western regime in Kyiv. Shortly after, pro-Russian Ukrainians and ethnic Russians in Crimea occupied government buildings, and Russia annexed the peninsula after a secession referendum. NATO war games in the Baltic, American arming and training of Ukrainian troops, and an evolving de facto integration of Ukraine into NATO and the EU sphere of influence preceded a Russian invasion of Ukraine in late February 2022.

Realists, liberals, and constructivists view this situation in different ways. Realists center their analysis on the security interests of states and power distribution. Western influence created a security threat to Russia and a relative power imbalance in favor of the West. Russia’s actions reflect a protection against Western encroachment to protect its security interests. 

Liberals emphasize domestic politics and the role of international institutions in the conflict. The coup in 2014 that brought into power a pro-Western government prompted Russia to undertake actions that would destabilize the country and pull Ukraine back into its trade orbit. A pro-Western population within Ukraine saw in NATO and the EU a way to advance their interests, reducing Ukrainian economic dependence on Russia.

Constructivists look more at diverging identities in the conflict. The attraction of pro-democratic Western identity stood in stark contrast to the authoritarianism of Putin’s Russia. Patriotic rhetoric from the Kremlin emphasized Russian identity and justified Crimean annexation as a reterritorialization of a historical Russian land.

International relations scholars view these main theories as both complementary and distinct ways of looking at the world. While staunch realists like Mearsheimer predicted the Russian reaction to NATO encroachment, many observers view these theories as tools in a toolbox of perspectives to consider when interpreting world events. Accordingly, it is important to understand that IR theories provide lenses for interpretation rather than a set of public policies that should be pursued. In other words, IR theory is value-free, seeking to understand how the world works. This outlook stands in contrast to ideologies of domestic politics or foreign policy, which are methods for achieving ends.

Foreign policy prescriptions may, however, follow from viewing the world through one of these theories. Offensive realism argues that international anarchy requires states to seek opportunities constantly to improve their relative power positions against other states. Defensive realism sees this strategy as misguided. Instead, states should enact foreign policies of restraint to avoid provoking other countries into belligerence. Liberals generally see economic interdependence, democracy, and international institutions as peacebuilding. As a result, liberals seek to expand democracy, trade relations, and international institutions on the global system and among other countries. They see liberal values as mutually beneficial for the United States as well as the target countries. Some, however, like Woodrow Wilson, George W. Bush, or Hillary Clinton, might like to impose these institutions and relationships by force. Like IR theory generally, these approaches can overlap and do not correspond to ideologies on the political spectrum or compass. IR theory is to foreign policy as economic theory is to economic policy. Both try to understand the world as it is and then derive policy that would best achieve ends sought. 


Koehane, Robert O. and Joseph S. Nye. Power and Interdependence: World Politics in Transition. Boston: Little, Brown and Company, 1977.

Morgenthau, Hans J. Politics Among Nations: The Struggle for Power and Peace. New York: Alfred A. Knopf, 1948.

Waltz, Kenneth N. Theory of International Politics. Boston: McGraw-Hill, 1979.

Wendt, Alexander. “Anarchy is What States Make of It: The Social Construction of Power Politics.” International Organization 46, no. 2 (Spring 1992): 391-425.

Note: The views expressed on Mises.org are not necessarily those of the Mises Institute.
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