James Holmes, a Naval War College strategy professor writing in The National Interest, throws some needed cold water on the idea that the United States and China are destined for war because of the Thucydides Trap—the supposedly inevitable clash between predominant powers and rising powers epitomized by the Peloponnesian War between Athens and Sparta, which was made newly popular by Harvard’s Graham Allison in his 2017 book Destined for War. Holmes cautions against claims that certain events or outcomes are “destined” in global affairs. There are no inevitabilities in history or international relations. Leaders make decisions that determine peace or war. 

Allison is not the first observer to misapply valuable lessons of history to current global politics. Other examples abound. Barbara Tuchman’s Pulitzer Prize–winning book about the origins of the First World War The Guns of August has been misapplied countless times as an example of events and historical-social forces outside of political leaders’ control resulting in war, when, in fact, it was decisions made by political leaders in Austria-Hungary, Germany, Russia, Great Britain, and France that determined war or peace, as well as the intensity and length of the conflict. One only has to read George F. Kennan’s Decline of Bismarck’s European Order and The Fateful Alliance to understand that human agency, not historical inevitability, caused World War I.  

Austria-Hungary did not have to issue an ultimatum to Serbia following the terrorist murder of Franz Ferdinand and his wife. Germany did not have to give Austria-Hungary’s leaders a “blank check” to wage war against Serbia. Russia did not have to mobilize its army against Germany in the days leading up to August 1914. Great Britain, as Niall Ferguson brilliantly pointed out in The Pity of War, did not have to go to war at all. Germany did not have to renew unrestricted warfare at sea and send the Zimmerman Telegram to Mexico, which led U.S. President Woodrow Wilson to ask Congress for a declaration of war. There was nothing inevitable about any of those political decisions.  

Other observers have misapplied Sir Halford Mackinder’s important insights on global geopolitics—especially his heartland theory—to argue for U.S. intervention in the current Ukraine War and to exaggerate the threat posed by Russian aggression today. They often cite his famous dictum about control of the heartland of Eurasia and Eastern Europe leading to the establishment of a world empire. But Mackinder’s geopolitical theories evolved over time, and some of his intellectual disciples focus on his 1904 paper “The Geographical Pivot of History” and his 1919 book Democratic Ideals and Reality while ignoring his last word on the subject—a 1943 article titled “The Round World and the Winning of the Peace,” in which he modified the heartland theory, proposed an Atlantic alliance, prophesied the rise of China and India, and foresaw the establishment of a global balance of power.  

In the early 1950s, the formation of the Sino-Soviet alliance persuaded many in the United States and the West that Mackinder’s nightmare scenario of a hostile and united Eurasian landmass bidding for a global empire had come true. But as events unfolded, it became clear that geography was not destiny. Political leaders in China and Russia (Mao Zedong and Khrushchev) made decisions that led to the Sino-Soviet split, and more than a decade later decisions by political leaders in the United States and China (Nixon and Mao) exploited that Eurasian great-power split to undo Mackinder’s geopolitical nightmare.  

Perhaps the most misapplied inevitability by political leaders and international relations observers is the “lessons of Munich,” popularized by Winston Churchill in the first volume of his history of the Second World War, The Gathering Storm. Churchill argued that the Western powers’ appeasement of Hitler—epitomized by Prime Minister Neville Chamberlain’s Munich agreement, which he claimed meant “peace in our time”—made war more likely, which in this instance it clearly did. Churchill recounted Hitler’s successive acts of aggression that produced no firm response by the Western democracies and thereby persuaded Hitler that the democracies lacked the will to resist his global ambitions. Since then, political leaders and observers of international politics have applied the lessons of Munich to virtually every international crisis that involves an act of aggression.  

The “domino theory” of the 1950s and 1960s was a byproduct of the misapplication of Munich. The result was the disastrous U.S. military intervention in Southeast Asia because Americans were told that if South Vietnam fell to the communists, the rest of Southeast Asia, the Philippines, Indonesia, and quite possibly Australia and India would too. The lessons of Munich have also been cited as a reason to provide military assistance to Ukraine (with some even suggesting direct U.S./NATO military involvement in the conflict) and to give security guarantees to Ukraine when the war ends, perhaps including welcoming Ukraine into NATO. If Ukraine falls to Russia, proponents of this theory say, the Baltic States and Poland will be next, and then Germany, France, and the rest of Western Europe will fall prey to Russian aggression. Chamberlain’s confident visage as he waved the piece of paper that symbolized his deal with Hitler after returning from Munich has made its appearance time and time again in arguments for military action and defense guarantees that resulted in military involvement.    

The Thucydides Trap is simply the latest misuse of theories of inevitability to explain global conflict. It’s as if China’s President Xi Jinping as the rising power challenging the existing preeminent power has no choice but to wage war to replace the existing hegemon. But, of course, Xi does have a choice. And so does President Donald Trump. The two countries are not destined for war, though it is a possibility. Throughout the Cold War, direct military conflict between the United States and the Soviet Union was possible, but the political leaders in both countries avoided a direct clash of arms even as they engaged in proxy warfare around the globe. Even Churchill supposedly said that in most instances it is better to jaw-jaw than to war-war. 

None of this means that we cannot learn from history—it remains the greatest teacher because it records the actions and reactions of human agency over the course of thousands of years and exposes the wisdom and the follies of the past. But no two episodes of history are exactly alike. There is no doctrine, no general law, no one-size-fits-all theory that applies everywhere and at all times.  

As Holmes notes, the Thucydides Trap gets some things right about the actions of nations and the decisions of political leaders, but it does not explain everything a nation does or every decision made by its leaders. There was some validity to the domino theory too—after South Vietnam fell to communist rule, Laos and Cambodia did as well, but the rest of Southeast Asia, the Philippines, Australia, and India did not. And Mackinder’s geopolitics provided a useful framework within which to assess the global balance of power in the twentieth century—indeed, it still does today, but it is a framework instead of a precise road map with which to navigate global politics. 

Let’s give Thucydides the last word. In the History of the Peloponnesian War, he identified war’s most common motivators as fear, honor, and interest—all of which are based in each instance on human perceptions. Doctrines, theories, and general laws can shape those perceptions, but in the end it is human agency that decides for peace or war.