How does the world work — International Relations in a nutshell

Adilson S. Proença
5 min readDec 4, 2022


Greek troops rushing forward at the Battle of Marathon (490BC), depicted by the artist Georges Rochegrosse in 1859.

The field of study of International Relations (IR, for short) seeks to understand and predict the interaction between different actors (countries, international organisations, individuals, etc.) in the international arena. Internationalists — the people who hold a degree in IR — rely heavily on theories to help them answer various questions, such as: why countries behave the way they do? why do wars occur? why do countries need nuclear weapons if they hope they’ll never have to deploy them? Despite the fact that IR is a relatively modern field of study (about a hundred years since the first course was established), the foundations of its early theories are couched on the ideas of scholars and thinkers that date back centuries and even millennia! It would take a whole book to summarise all the different theories that one can use to explain international politics. Nonetheless, it can all be boiled down to two rivalling theories: realism and liberalism.

Before I jump into that, though, here’s something important. By writing this text I want to achieve two goals. Firstly, I want to flesh out the core tenets of both the realistic and the liberal schools of thought in IR to provide the reader with two pair of lenses through which he or she will be able to make sense of international events like the on-going Russo-Ukrainian war. Secondly, I want to establish a theoretical foundation upon which, in an upcoming text, I will attempt to explain why Russia has decided that the benefits of invading Ukraine outweigh the costs of the backlash from the West that the Kremlin has been suffering. I’ve decided to write this text in English because I know I can reach more readers, some of which are my own students. I’ll also provide versions in Portuguese and French.

Edward Carr was the first contemporary theorist who put together a structured rationale to explain the world. He argued that in realism there is no moral dimension. This is an idea that comes from Niccolo Machiavelli’s difference between individual morality and statesman morality. This means that for a realist what is successful is right and what is unsuccessful is wrong. Carr also drew on the ideas of the Greek philosopher Thucydides to explain that the world is an anarchical system, and on Thomas Hobbes’ writings to argue that it is not possible to create a Leviathan in the international system. This means that, unlike inside a country where the State holds power monopoly over the citizens and controls them through laws, at the international level, it is impossible to create a supra-state government to control other countries, because countries would never agree to relinquish all their sovereignty (the ability to decide for themselves). Carr’s best-selling “Twenty years of crises: 1919–1939” paved the way for a subsequent IR theorist: Hans Morgenthau.

Morgenthau’s 1948 book, “Politics among nations”, was so successful that it became the basic way of explaining world diplomacy and it influenced most of the United States post-World War II foreign policy, up until the mid-1970s. In a nutshell, a core tenet of Morgenthau’s theory is the essence of human nature. In his view, humans are naturally dominated by the desire for power, and this made them inclined towards violence as they struggled for power. Morgenthau called this the animus dominandi (animal dominance), and he believed that because countries are ultimately controlled by people, then countries tended to behave violently in search for power.

In the late 1970s Kenneth Waltz’s best-selling “Theory of International Relations” brought on a more scientific approach to the field. Waltz’s theory is called defensive-structural realism. Basically, the scholar believes that it is not the human nature that explains why countries behave the way they do, but, rather, the anarchical structure of the system. For Waltz, the absence of a “world night watch creates an atmosphere of self-help. This, in turn, leads countries to the realisation that they are the only ones to be held accountable for their own security, and that they had better take the necessary actions to be able to protect themselves, because they can never be certain whether other countries harbour good or evil intentions towards them. For Waltz, this set of constraints means that countries will then seek to maximise their relative power so that they can deter potential threats. Waltz’s theory takes the name “defensive” realism precisely because, in his view, countries will not seek to amass the most power they can, because this would tip too much the balance of power among countries and make others feels insecure. In Waltz’s theory, the bipolar system was the safest one, because it meant “fewer fingers on the trigger”. When this system was intentionally dismantled in the early 1990s, Waltz’s structural realism needed a review. This is where John J. Mearsheimer’s works come in.

John J. Mearsheimer is one of the advocates of the realistic school of thought still alive. Like his predecessors, Mearsheimer upholds most of the core tenets of realism like the anarchy of the international system and countries’ need for power and the potentially violent competition that comes out of that. Unlike his predecessors — and particularly unlike Waltz –, John thinks that countries will seek to have all the power they can get (and not just enough, like Waltz argued). Because of this, Mearsheimer’s theory is called offensive-structural realism.

In IR’s history, what came to be known as idealism first emerged in the aftermath of World War I. Woodrow Wilson, the American president during WWI, was one of its first proponents in the modern age. Wilson’s idealism can be seen in his Fourteen Points, particularly the 14th one, which upheld the creation of the League of Nations. Wilson’s ideas find their theoretical roots in early thinkers like John Locke, Jeremy Bentham, and Immanuel Kant.

The idealistic tradition is associated with the emergence of the modern liberal State (after 1789), which is the reason why it is commonly referred to as liberalism (not in the economical sense of the word). In short, liberalism acknowledges that the human nature is fundamentally selfish and competitive, but, unlike their realist counterparts, the liberals are more optimistic about the possibility of breaking that trend for violence through progress and reason. The idea of progress is a central pillar of the liberal school of thought in IR. Liberals believe that cooperation based on mutual interest among countries will eventually prevail, because modernisation creates interdependence and the need for cooperation. This, in turn, makes it clear for countries that the cost of violence usually outweighs the benefits.

At the break of World War II, the liberal thinking in IR was eclipsed by the realistic school. That’s understandable, as liberals proclaimed, after WWI, that countries had entered in a new age of rationality and that the League of Nations would help prevent a catastrophe like WWI. Just like realism, the liberal though has evolved over the years and many branches have been shaped into new theories.



Adilson S. Proença

An International Relations degree holder; a language, history and economics aficionado; and a soon-to-be Economist who sees writing a thought-untangling act.