Summary: This short entry, in less than 450 words, distinguishes two particular meanings and connotations of oligarchy, introduces a few scholars who write about the concept, and discusses its connections with elite theory.
The first usage of oligarchy comes from the original Greek and means "rule by the few." In this sense, the concept is quite distinct from monarchy or autocracy--rule by one person--and democracy--rule by the many, by the people. As both Plato and Aristotle point out, oligarchy tends to approximate plutocracy, where power and privileges are based on wealth.
Oligarchy in its second sense is a management method used in political organizations. In this conceptual view, power rather than wealth is the key to political success. Numerous scholars point to oligarchic tendencies among those in positions of power. One significant example is Roberto Michels' iron law of oligarchy. Critics of Michels' law are divided into those who find the process destructive and those who believe it is simply inevitable. C. Wright Mills, Mosca and Pareto connect oligarchy to the study of elites and elite theory. Again, writers in this camp are divided between the danger and the inevitability of elites.