Vilfredo Pareto's thesis that governing elites decay and are replaced by new ones drawn from below or from rival elites, so that history is a succession of ruling minorities rather than a progression towards rule by the many.
In more detail
In his Trattato di sociologia generale (1916), Pareto contrasted elites of "foxes", who rule by cunning and bargaining, with "lions", who rule by force and conviction, and argued that an elite which blocks the rise of capable outsiders accumulates resentment and invites violent replacement. Gradual co-optation of talent was, for him, the condition of stability. The idea influenced elite theory and studies of revolutions, but critics see it as too schematic and as having lent itself to anti-democratic politics.