The ancient Greeks had a theory called "anacyclosis", which stated that political systems move in cycles. First you start off with monarchies, which degenerate into tyrannies, which are replaced by an aristocracy, which degenerates into oligarchy. This is then replaced by a democracy, which itself degenerates into ochlocracy or mob-rule. After this, the cycle resets itself and you are back to one-man rule. We seem to be headed in this direction.