Cliodynamics

We describe a compartmental model that captures the spread of political dissent between a civilian population and security forces. Both groups are subdivided into "accessories" and "dissenters" with a "dissent bug" spreading from the latter group to the former in the same way a virus spreads from infectives to susceptibles. We provide conditions under which the corresponding system of two non-linear ordinary differential equations has either the origin or a non-trivial value as its unique asymptotically stable equilibrium.  The model is illustrated with data from the French Revolution and shows that the unraveling of the old regime is consistent with Chenoweth's rule, which postulates that no revolution has failed if more than 3.5% of the population is involved in "mass non-cooperation". We complement this metric with a dissension ratio equal to the civilian dissenting population divided by the security forces accessories —a ratio with a threshold value approximately equal to five as the old regime was collapsing.