The oligarchy is a form of power structure in which power effectively rests with a small segment of society distinguished by royalty, wealth, family ties, corporate, or military control. The word oligarchy is from the Greek words "ὀλίγος" (olígos), "a few" and the verb "ἄρχω" (archo), "to rule, to govern, to command". Such states are often controlled by a few prominent families who pass their influence from one generation to the next.
Oligarchies have been tyrannical throughout history, being completely reliant on public servitude to exist.
Robert Michels believed that any political system eventually evolves into an oligarchy. He called this the iron law of oligarchy. According to this school of thought, modern democracies should be considered as oligarchies. In these systems, actual differences between viable political rivals are small, the oligarchic elite impose strict limits on what constitutes an acceptable and respectable political position, and politicians' careers depend heavily on unelected economic and media elites.
Corporate oligarchy is a form of power, governmental or operational, where such power effectively rests with a small, elite group of inside individuals, sometimes from a small group of educational institutions, or influential economic entities or devices, such as banks, commercial entities that act in complicity with, or at the whim of the oligarchy, often with little or no regard for constitutionally protected prerogative.
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