The Intelligence Trap

Imagine a brilliant engineer who signs a bad contract because his spreadsheet looks perfect, ignoring a detail that a less accomplished colleague would have spotted in two minutes. This scene opens the discussion in David Robson's book: mistakes don't come from a lack of brainpower, but from how the brain uses its abilities. The smarter you are, the better you become at building convincing arguments, including arguments that convince yourself.

The central argument is unsettling. Robson shows that intelligence is good at solving problems with clear rules, but doesn't protect against cognitive biases, mental shortcuts known as heuristics that distort judgment. In several studies he cites, people with high IQs or advanced education were no less susceptible to these shortcuts, and sometimes more so, because they could build better justifications for the path they had chosen.

The book's title makes sense here: this isn't about foolish mistakes made by unintelligent people, but predictable mistakes made by smart people who trust their own reasoning too much. That shift in perspective changes the question. Instead of beating yourself up for being so foolish, it's worth asking which shortcut your brain took in that situation.

For decades, the standard measure of intelligence has been the IQ test, which assesses vocabulary, logic, working memory, and pattern-based reasoning. These tests are good predictors of academic performance and some career outcomes. The problem is that they measure the ability to solve clearly defined problems, but reveal almost nothing about what happens when someone has to make a decision alone in a messy, emotionally charged situation.

Robson argues that there's an ability separate from raw brainpower: the willingness to check your own answer, question what seems obvious, and look for contradictory evidence. Keith Stanovich, a psychologist who studied the subject, called the situation in which someone uses intelligence to think less rationally dysrationalia. It's not that the person can't reason; it's that they don't reason at precisely the moment they need to.

In real life, this happens when an experienced doctor clings to an existing diagnosis and ignores a test result that contradicts it, or when an analyst accepts a number that confirms a gut feeling. Intelligence supplies the argument, but the habit of looking at the other side of the story is missing.

One of the experiments most often cited in the book is the cognitive reflection test, created by Shane Frederick. One question says that a bat and a ball cost $1.10 together, and the bat costs $1 more than the ball. How much does the ball cost? The intuitive answer, ten cents, comes quickly and is wrong. Anyone who takes two seconds to check arrives at five cents.

The point of the test isn't the arithmetic, but the impulse. People with high scores tend to get more answers right because they generally question their first response. Robson notes, however, that even among the most intelligent, plenty of people fall into the trap because the wrong answer seems so logical that it sets off no internal alarm.

The practical lesson is easy to describe and hard to follow: when a conclusion comes too quickly and confirms what you already wanted to think, it's worth slowing down. That pause doesn't solve everything, but it opens the door to the deliberate thinking the book advocates.