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What Is the Thucydides Trap?

The Thucydides Trap is a phrase coined by the Harvard political scientist Graham Allison for the danger of war when a rising power threatens to displace a ruling one. It comes from Thucydides’ explanation of the Peloponnesian War (431–404 BC): that the growth of Athenian power, and the fear it caused in Sparta, made war inevitable. Allison’s project studied 16 cases of such rivalry over 500 years and found that 12 ended in war; he applied the idea to the United States and China in his 2017 book Destined for War. Critics accept the warning but dispute the case list and point out that Thucydides himself gave more than one cause.

Where the phrase comes from

Thucydides, an Athenian general who wrote a history of the war between Athens and Sparta, separates the complaints each side made in public from what he calls the truest cause. In the usual English rendering of his first book (1.23), the war was made inevitable by the growth of Athenian power and the fear this caused in Sparta. After the Persian Wars Athens had built a maritime empire out of the Delian League; Sparta, the established land power of Greece, watched it grow for half a century before the fighting began in 431 BC.

Graham Allison, founding dean of Harvard’s Kennedy School, used the sentence as the name for a pattern. He introduced the phrase in a 2012 article and set out the argument at length in Destined for War: Can America and China Escape Thucydides’s Trap? (2017).

The 16 cases

Allison’s Thucydides’s Trap Project at Harvard’s Belfer Center looked at 16 instances over the past 500 years in which a rising power challenged a ruling one. Twelve ended in war. Among the war cases are Habsburg Spain against France in the sixteenth century, the Dutch Republic against England in the seventeenth, and Germany against Britain before 1914. Among the four that did not end in war are the United States overtaking Britain in the early twentieth century and the Cold War between the United States and the Soviet Union.

His conclusion is not that war is certain. It is that such rivalries are dangerous, and that the peaceful cases show the outcome depends on choices made by both sides.

The objections

Historians and political scientists have raised three main objections. First, the case list: critics argue that cases were chosen and coded in ways that inflate the pattern, that some ‘ruling’ and ‘rising’ labels are debatable, and that wars between great powers had many causes besides a shift in power. Second, Thucydides: specialists point out that his history gives detailed accounts of other causes, from the quarrels over Corcyra and Potidaea to decisions made by individuals, and that one sentence is a thin base for a general law. Third, the present: some argue the US-China comparison overstates how close the two countries are in power, or understates the effect of nuclear weapons.

Even critics tend to grant the narrower point: a rising power and an anxious established one can misread each other, and that misreading has a long record of ending badly.

What most scholars accept, and what stays contested

Frequently asked questions

Who coined the term Thucydides Trap?

Graham Allison of Harvard University, in a 2012 article, developed in his 2017 book Destined for War.

What did Thucydides actually say?

In Book 1 of his history he wrote that the truest cause of the Peloponnesian War, though the least spoken of, was the growth of Athenian power and the fear it caused in Sparta, which made war inevitable.

How many Thucydides Trap cases ended in war?

Allison’s project counted 16 cases over 500 years; 12 ended in war and 4 did not.

Is the Thucydides Trap about China?

Allison applied it mainly to rivalry between the United States and China, which is why the phrase became widely used after 2017. The idea itself is general.

Sources and further reading