The whys and hows of International Relations: classical Realism vs. classical Liberalism


Author: Covadonga Bermejo Cosmen. Double Degree in Law and Business Administration, Honours Program.


The theories that explain the whys and hows of International Relations propose different approaches considering ideas about human nature, politics and foreign policy. Each of the theories propose an analysis that contributes to a better understanding about society, conflicts, economy and institutions.  

Needless to say that explaining many theories would be complex, inefficient and overwhelming. For that reason, two theories will be exposed: classical Realism and classical Liberalism. Although each school of thought bring opposing views, these doctrines hold some common assumptions.

First and foremost, they all highlight the importance of theory when trying to explain international relations. This implies that the different events that take place within the international framework are not just “facts” that emerge nonsense but follow chosen assumptions made about the world.

Second, these theories come from very different origins and times and all of them offer explanations, perceptions and solutions of social problems and dilemmas. In addition, each theory is nurtured by influential philosophers of different epochs and environments. This entails that those problems and the respective solutions are not static, they have been evolving in parallel with humankind.


Las teorías que logran explicar los porqués y los cómo de las Relaciones Internacionales aportan diferentes perspectivas de la naturaleza humana, la política y la política exterior. El análisis que hacen no sólo es meramente teórico sino que tiene un gran alcance práctico en torno a la sociedad, los conflictos que se suscitan en ella, la economía y las instituciones.

La enorme cantidad de teorías que existen hace que resulte ineficiente y extremadamente complejo hacer un análisis detallado de cada una de ellas. Por ello, esta narración profundizará en dos de ellas –el Realismo clásico y el Liberalismo clásico–, detallando su impacto en las Relaciones Internacionales.

El objeto no es recrear un posible conflicto entre las dos teorías sino tratar de dar entender las soluciones que cada teoría da a determinados problemas sociales.

Classical Realism

This theory dates back to the 5th century b.C. and relies on historian Thucydides and his explanation of the Peloponnesian War between Athens and Sparta, and has been expanded by Hans J. Morgenthau (1904-1907) –a German refugee lawyer in the US during the Second World War and Professor at the University of Chicago–, among others.

Prior to making an approach of classic realism’s assumptions and their impact on international relations, is important to scan the pillars of this theory. Realists authors such as Niccolò Machiavelli (1469-1527), Hobbes (1588-1679), and Morgenthau, have in common their negative perception of humanity. According to them, humans are selfish, cruel and driven by unconstrained passion that responds to fear and insecurity impulsed by the state of nature, which is a constant fight in order to survive.

Inner security turns over on the outside converted into desire for coming to power as the main end, attacking others if needed.

Moreover, realist scholars explain categorically the nature of state – considered the unique international actor – and its politics. States are established through social contracts in order to protect each nation from foreigners’ attacks and each state can act coercively when inner disorder arise. Indeed, states are also power seekers – as they are the result of many power-driven human beings – that would promote any conflict to impose their dominance. As a consequence, states’ domestic and international politics are mere manifestations of concern for survival in which the state will defend the use of force even if it is irrational or immoral because the ends justify the means.  

Machiavelli statue in Florence. Photo by Rafael Robles L. on / CC BY


Classical realists recognize that superpowers are their own worst enemies when success because they suffer from biases that lead to feel above the rest of the community. Such self-understanding is not impeded and give rise to mistaken and aggressive foreign policies. On the one hand, they propose a clear solution: a centralist state that enforces laws and restricted cross-border moves.  They see cooperation and alliances as a double-edged sword; because states compete among each other and therefore, cooperation is seen as a weakness and destabilizing since nothing stops one ally to betray you in the future.

Thucydides and Morgenthau understand that balance of power has contradictory results seeking peace, especially because every single state aims feeling under protection.  In the case states and leaders defend consistently status quo and display determination to fight for it, competition for power is restrained and war may be avoided successfully. On the contrary, when a high percentage of states fight simultaneously for achieving protection –to the detriment of the other international players–, tensions may rise and a war is prone to break out.

Classical Liberalism

The other big theory that approaches humanity and illustrates international relations is classical Liberalism, which is composed of economic, social and political disciplines. One of the most important liberalist thinkers are: John Locke (1632-1704), Adam Smith, (1723-1790), Ludwig von Mises (1881-1973) and Friedrich Hayek (1899-1992).

It is necessary pointing out key principles around which Liberalism is constructed. Liberalism beliefs in freedom, individualism, non-religious natural law, a limited state and the rule of law.

For liberals, the individual is prior to the collective and they consider the groups lack entity – interests or ambitions themselves–: they only assembly individuals.

The basis for these assumptions is its vision on human nature. Man is seen to be a mixture of reason and passion. Reason provides humankind with tools to adapt to changes and expand intellectual capacities. However, reason is not capable of everything and in fact, it is fragile and subject to passions or temptations of which man cannot get rid of. Nevertheless, liberals do not see man as cruel nor evildoer morally, but he can tend to it. Basically, liberals propose this definition of human nature and accept it how it is without trying to change it. And contrary to realists, they understand the nature of humans is harmony.

Focusing on international relations, the ultimate goal of Liberalism is maximizing individuals’ freedom – the area in which the individual decides without any interference from other humans or the state –.

Every individual has inherent –natural– rights to life, liberty and property and the respect for others’ rights and tolerance among states allow them to live together in society and even cooperate. When states are respectful, individuals foster international private relations and they promote trade and other mutual advantageous actions.

Liberalists firmly enforce trade partners in international relations. Spuring trade may increase tolerance, mutual understanding and empathy, as well as it will reduce the cultural barriers. Regarding wars and taking into account that state action is human action, they cannot be completely prevented but at least minimized. We can think that two close trading partners who continuously negotiate and maintain a stable and profitable political relationship will refuse to promote a conflict between them. Not to say that liberalists consider democracy the most suitable way of promoting individual freedom and tolerance; demonstrating that a state that respects its citizens will respect other states citizens too. Hence, democratic states are more peaceful and prone to cooperate with other peaceful allies.

States are representative institutions that constitute the principal international actors. It is permanently under construction in the sense it depends on social groups, preferences, and the purposes of society. Although the states’ mission is protecting natural rights and maximizing individual freedom, states have been proved to be the most abusers of these rights and therefore their task shall be limited by constitutions, laws and the separation of powers.  There is also space for international agreements to solidify practices or to smooth states interactions. But as the risk of overregulation exists, the classical liberal rule of thumb will defend avoiding a supreme authority imposing rules and beforehand –although it may be needed in exceptional circumstances, for instance during the Cold War period–. They claim to prefer a spontaneous order like the free market in which countries negotiate and cooperate to avoid suffering others’ dominance, to promote development and to safeguard the so-called peaceful democracy and therefore, their own security.

All in all, principles of each theory are its own foundations and biases, and both theories have proven not to be sufficient explaining the complexity of international relations or at least, international relations in the manner we know them. Given human nature, the wide variety of theories that arise and prosper and its limitations, there is no guarantee that the problems that concerned us will be solved. As a consequence, it will be meaningless declaring which theory approaches foreign policy best, since they have opposing views about humans, and in consequence propose totally different solutions.

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11 de noviembre de 2020

ISSN 2340 – 2482

Key words: classical Realism, classical Liberalism, Political theories, Human nature, Philosophy, International relations, Peace, War

Palabras clave: Realismo clásico, Liberalismo clásico, Teorías políticas, Naturaleza humana, Filosofía, Relaciones internacionales, Guerra, Paz



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The whys and hows of International Relations: classical Realism vs. classical Liberalism by Covadonga Bermejo Cosmen is licensed under a Creative Commons Reconocimiento-NoComercial 4.0 Internacional License.