Known unknowns and unknown unknowns: The map of what we don’t know In February 2002, Donald Rumsfeld, then United States Secretary of Defense, delivered a response at a Pentagon press briefing that became one of the most quoted — and most mocked — statements in modern political life. Asked about the evidence linking Iraq to… Read more

The tools we think with There is a map of London’s Underground railway that has been reproduced more than a billion times. It appears in every station, on every tourist guide, on the phones of every visitor who has ever tried to find their way from Paddington to Borough Market. It was designed by an… Read more

Why your brain is always compressing In the summer of 1956, the cognitive psychologist George Miller published a paper in the journal Psychological Review that has become one of the most widely cited in the history of the field. Its title was deliberately playful: “The Magical Number Seven, Plus or Minus Two: Some Limits on… Read more

There is an experiment so simple that it requires nothing beyond the page you are currently reading. Focus your eyes on a single word somewhere near the center of this line. Without moving your eyes, try to make out the words at the far left and right margins. They are within your visual field —… Read more

What is a model? Explanatory power, prediction, and the art of knowing the limits There is a map of the London Underground that has been reproduced more than a billion times. It hangs in train carriages and ticket halls, appears on tourist guides and phone screens, and is recognized by more people worldwide than almost… Read more