whatTwo squares of four hundred people, each person holding a private threshold: the number of rioters they must see before they join. The same two hotheads spark both squares. Each beat, everyone whose threshold the crowd has met steps in, or nobody does and it stops dead. Below each square is Granovetter's picture: the cumulative threshold curve against the diagonal, with the riot climbing until the curve crosses the line.

whyThe trap: both crowds have the same average threshold. The left crowd's willingness is an even staircase, every step present, so each joiner recruits the next and the cascade runs to a full riot. The right crowd is a tight consensus around the very same mean, but with the low tail missing nobody carries the spark from two rioters to twenty, and it fizzles at half a percent. Measured here: means within two of each other, outcomes one hundred percent against zero point five. The average predicts nothing; the tail decides.

howGranovetter's threshold model, run as a replaying cascade with a half-second beat. Draw on either curve panel to resculpt that crowd's temperament; thresholds are resampled from your curve, the means are reprinted so you can hold them equal yourself, and the cascade replays. Click a square to replay at any time. One integer seeds the crowd.