We’re fighting a Vietnam redux. It’s 1938 all over again. The Guns of August are around the corner. A new Cold War has begun.

A raft of historical analogies has swirled around Ukraine coverage that purports to explain a war few experts saw coming. Do peacemakers like French President Emmanuel Macron risk being duped like former British Prime Minister Neville Chamberlain at Munich? Or is this moment another 1914, and a wider European mobilization lurks around the corner?

The analogies writers apply to Ukraine shape how it’s understood—and how the public thinks the war will end. If this is really akin to World War I, Europe’s rulers should be careful not to escalate in the face of Russian mobilization—the opposite of what Germany announced it would do this year. But if the moment is like the 1938 Munich Agreement, negotiating with Russian President Vladimir Putin will encourage him to take more than just the four oblasts in eastern Ukraine.

Thinking about today through the lens of the past has a long provenance in the corridors of power. American administrations throughout the 20th century used historical analogies to frame the crises they faced, likening them to the Peloponnesian War between Athens and Sparta, the surprise attack on Pearl Harbor, mission creep in Vietnam, the humanitarian disaster in Somalia, the bipolar tensions of a new Cold War—and, of course, everyone’s favorite analogy, appeasement at Munich. Putin himself has deployed historical analogies (including World War II appeasement) to justify the war in Ukraine, and Ukrainian President Volodymyr Zelensky has countered with his own.

There’s a reason that historical analogies like these are never in short supply. Analogical thinking is deeply embedded in the world’s cognition—how experts make sense of new situations—in what international relations academic Aidan Hehir calls an “inherent psychological compulsion.” Experts can’t help but think analogically. But because the choice and application of analogies is open to individual biases and errors, their use at the highest levels of policymaking carries serious risks.

For the last several decades, scientists have argued analogies are not just rhetorical devices but cognitive heuristics—mental shortcuts for making sense of the world. Baked into fundamental cognitive processes, heuristics help experts process new information by simplifying its complexity and organizing it according to preexisting mental structures. Without these shortcuts, people wouldn’t be able to function, overwhelmed by the phenomena of day-to-day life.

When people think analogically, they transfer meaning from one thing to another, understanding something present in terms of something past. But as with any shortcut, analogies have a downside. Heuristics distort the underlying phenomena of life, producing cognitive biases, such as the halo effect, confirmation bias, and overconfidence. Outlined by English philosopher Francis Bacon and popularized by psychologist Daniel Kahneman’s Thinking, Fast and Slow, these biases mean experts’ first and often most powerful judgments can be the most misleading. When experts use a historical analogy to understand the present, they risk importing the errors and biases inherent in the shortcut.