Thucydides Trap: Definition, Theory & Historical Examples

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  • 0:04 The Thucydides Trap
  • 0:51 Thucydides
  • 1:57 Allison's Research
  • 3:50 Modern Issues
  • 5:54 Lesson Summary
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Lesson Transcript
Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

Thucydides was an ancient Greek historian. So, what can he teach us about modern international relations? In this lesson, we'll examine the Thucydides Trap, and see how ancient history can help us prevent future wars.

The Thucydides Trap

History is littered with examples of things that seemed like good ideas at the time, but that turned out to be disastrous. While we've recognized these pitfalls for a long time, we now have an official term for at least one of them. In 2015, Harvard political scientist and professor Graham Allison identified a scenario he calls the Thucydides Trap. Basically, the Thucydides Trap says that as a rising power challenges the dominance of an established power, that dominant power is likely to respond with violence. It's a model for predicting when warfare is likely between two nations, but also a way to propose alternative solutions meant to prevent warfare. After all, the whole point of identifying a trap is to avoid it.


The Thucydides Trap is a political metaphor, so in order to understand it we need to look at its namesake. Thucydides was a 5th-century BCE Greek historian and politician who wrote the most famous account of the Peloponnesian War. Here's what he observed in the outbreak of the nearly 30-year conflict that rocked the Greek city-states.


Sparta was the hegemony, or dominant power, of the Aegean. Athens, however, was growing so quickly that Sparta got spooked. They worried that Athens would soon become a real threat to their power, so they attacked preemptively. And that's the trap. Athens' ambition and Sparta's fear of losing power drew the two into conflict, even when no one expected it. When Sparta attacked Athens, it forced the other Greek city-states to pick a side, and a massive Greek war ensued that lasted for decades. Thucydides would later write that the entire Peloponnesian War was due to ''the growth in power of Athens, and the alarm which this inspired in Sparta.''

Allison's Research

According to Graham Allison's article, the Thucydides Trap is one of the great misjudgments of history. Nations overexert their growing influence, stronger nations see a threat to their power, and the result is warfare. When Allison presented this theory in 2015, he claimed that his research team at the Harvard-affiliated Belfer Center identified 16 cases over the last 500 years that mirrored the Sparta/Athens example of a growing power threatening a dominant one. Of those sixteen cases, twelve of them resulted in warfare.

While these cases drew from events across the last five centuries, perhaps the most notable example was the outbreak of World War I. In the early 20th century, Germany began industrializing rapidly under Kaiser Wilhelm II. Their economy skyrocketed, and they used this wealth to start building an industrial navy. The rapid and ambitious growth of Germany worried Europe's dominant power, Great Britain, and the British prime minister put more resources into their own militarization, starting an arms race. Prime Minister Eyre Crow even posed this question to the king: could German growth threaten the very existence of England?

Wilhelm II and Edward VII together in 1904

We have to remember that, at the time, a war between these nations was unthinkable. They were in an arms race to see who was the greater power, but violence between them seemed impossible. After all, Kaiser Wilhelm was King Edward VII of England's cousin. When the King died, the Kaiser was at the funeral, where he praised England and assured the concerned Theodore Roosevelt that war between the two nations was unimaginable. Four years later, they were at war. England and Germany had fallen into the Thucydides Trap of assuming that war was impossible and failing to safeguard against it.

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