Humans are weak. Humans need leaders. Tigers make great leaders. Rawr.
Jean-Jacques Rousseau believed in a State of Nature that people would be kind to one another and peaceful. This formed the idea of Direct Democracy, a form of government where everyone can vote on decisions being made.
John Locke is the man who came up with the idea of a Republic, the government us Americans are living in today. Since people in a State of Nature would be rational and organized (according to him), he believed that people needed leaders, but could choose their managers themselves.
Do not mistake this man for a tiger! Thomas Hobbes, the first of the three philosophers, believes that people in a State of Nature would act like ANIMALS. People needed a leader! Thus, Autocracy was born. (Note: Hobbes does make a good comic character)