Realism: the world is a dark forest.
Realism asks one question first: who has the power?
Realism starts from the fact you learned in chapter one: no world police. Survival comes first. Power is the thing that makes survival possible.
Realists look at military capability, geography, industrial capacity, population, and alliances. Morality may matter to speeches. Power decides whether a state can act on what it says.
From this view, Russia invaded Ukraine because Moscow calculated that Ukraine was vulnerable and that direct Western intervention was unlikely. That does not make the war moral. It explains the calculation.
States act rationally
States calculate costs and benefits under pressure. They pursue security because no one else guarantees it.
Power is not everything
Realism often underestimates identity, domestic politics, ideology, and leaders who miscalculate.
Liberalism: cooperation is possible.
Liberals agree the world is anarchic. They just think rules, trade, and institutions can tame the danger.
Liberals look at the European Union and see a political miracle. Countries that fought for centuries now share courts, markets, laws, and a currency. Cooperation did not appear naturally. Institutions made it easier.
The core liberal claim is simple: trade raises the cost of war, democracy changes incentives, and institutions reduce uncertainty. If states can see the benefits of cooperation and trust the process, peace becomes rational.
When Russia invaded Ukraine, liberals saw a rule-breaking event: borders changed by force. Sanctions, ICC investigations, NATO coordination, and UN votes are liberal tools for raising the price of aggression.
Interdependence
Trade makes conflict expensive. If your prosperity depends on your neighbor, war starts to look irrational.
Institutions
Organizations create habits, forums, rules, and monitoring. They make cheating more visible and cooperation more predictable.
Constructivism: ideas shape reality.
Constructivists ask why countries want what they want. The answer is identity, norms, memory, and story.
The material world matters. Weapons, money, ships, oil, chips. Constructivists add the missing question: what do people believe those things mean?
Russia tells itself a story in which Ukraine is not fully separate, the West is hostile, and Moscow has a historic mission. Ukraine tells a story in which it is a sovereign European democracy escaping empire. The war is fought with artillery and narratives.
Ideas change interests. Germany and the United States were enemies, then allies. The material facts did not magically disappear. The relationship changed because identity and norms changed.
Identity
What a state thinks it is shapes what it thinks it wants.
Norms
Shared beliefs about acceptable behavior. Norms can make old practices unthinkable.
Use all three on one event.
A single lens gives you a clean answer. Three lenses give you a better one.
Why is China building a larger navy?
“A rising power wants military room to operate.”
China is a rising great power in an anarchic system. A stronger navy lets Beijing deter rivals, project power, and challenge US dominance in the western Pacific.
“The buildup threatens the institutions that made China rich.”
China benefited from open trade and stable sea lanes. A naval arms race increases uncertainty and makes cooperation harder, even when everyone profits from peace.
example. The South China Sea disputes turn trade routes into security problems.
“The navy carries a story of national restoration.”
China tells itself a story about recovering central status after a century of humiliation. A blue-water navy is not just hardware. It is proof that China has returned.
The complete picture is not a compromise between the three. It is a stack. China's navy is rational strategy, inside institutions that make war costly, powered by a story of national restoration.
Have you got it?
Which lens focuses most directly on identity, norms, and national stories?
Constructivism asks how ideas, identity, memory, and norms shape what states want. It is the lens that explains why the same material facts can produce different behavior.
Sources & further reading
Five things you now understand
- 01
Realists see power
They ask who has the capability, who feels threatened, and what survival requires.
- 02
Liberals see institutions
They ask how trade, democracy, treaties, and organizations change incentives.
- 03
Constructivists see ideas
They ask how identity, norms, memory, and stories shape interests.
- 04
Each lens misses something
Power without ideas is too cold. Ideas without power are too light. Institutions without politics are too neat.
- 05
The trick is layering
Use the lenses together. Start with power, add institutions, then ask what story each actor thinks it is living inside.