threshold phenomena

Whenever we have threshold phenomena, whether in physical, biological, or social systems, the configuration of the system at the moment when the threshold is reached becomes unstable and the slightest, even infinitesimal, displacement of the configuration in a proper direction leads eventually to a finite change in the configuration of the system. Therefore a change in the behaviour of a single individual, no matter how small, may precipitate in an unstable social configuration, a process that leads to a finite, sometimes radical, change.

– Nicolas Rashevsky, mathematician, 1805-1964