Also, one of the functions of oligarchies in general can be summed up by this Orwell quote from 1984 in the chapter "War is Peace":
"It is a deliberate policy to keep even the favoured groups somewhere near the brink of hardship, because a general state of scarcity increases the importance of small privileges and thus magnifies the distinction between one group and another."
In peace times, oligarchies do this with 'power' and 'control', only those who are let into the 'oligarchy' are rarely ever let into the 'inner circle' of the oligarchy.
Thus, by creating a 'scarcity' of power and how it is distributed, an oligarchy can give the illusion that it is sharing power when in fact, it isn't sharing power. In that situations, a general sense of paranoia and denial of objective reality becomes the norm, and objective reality is only cited when it is useful to do so, and then shoved back into oblivion when objective reality and truth become inconvenient. In either situation, the truth, as it were, as Orwell notes, the truth and the very act of telling it (or even thinking it) becomes a revolutionary act.