Vilfredo Pareto (1848-1923) was an Italian engineer, philosopher, economist, sociologist and political scientist, famous, among other things, for his theories about “the elites”.
In his theory of the “circulation of the elites” he argues that social mobility is fundamental for the peaceful continuity of social order: as long as the elite is open to the influx of capable elements from the lower classes, the system is able to rise up to the challenges it faces. When the elites shut themselves off and do not assimilate exceptional individuals from the lower social strata, an imbalance is created that can result in a violent overthrow of the ruling class by a new one capable of governing.
Drawing on that theory we argue that democratic systems have evolved in a way that an overthrow of the elite can happen without violence, but by democratic vote. Lack of social mobility, says Pareto, results in an elite detached from the daily challenges of the common man and a sense of disenfranchisement of the voters.