The Great Mental Models Volume 3: Systems and Mathematics

by Rhiannon Beaubien

What Popular Culture Gets Wrong about the Butterfly Effect The image of a butterfly flapping its wings and causing a typhoon is a vivid one, and it’s no surprise it went on to inspire endless films, books, songs, and motivational quotes. It’s unusual for a mathematical idea to become so mainstream. The idea of a tiny thing having a big impact on the world is powerful. But this is a misreading of the actual meaning of the butterfly effect.1 It’s not that the wing flap causes the typhoon; it’s that the difference in starting conditions between a world where the butterfly flaps its wings and one where it doesn’t is sufficient to mean a typhoon in one and not the other. Chaotic systems are so sensitive to starting conditions that the minutest differences can lead to highly divergent outcomes. We cannot, however, look at an outcome and say that a particular change in conditions caused it. Within chaotic systems, no moment is any more significant than any other. Every single moment changes everything that happens after.