Thomas Hobbes: An English philosopher who developed some of the earliest forms of social contract theory in his work "Leviathan."
Jean-Jacques Rousseau: A philosopher who expanded on the idea of the social contract in his works, arguing that citizens agree to surrender some freedoms to achieve community benefits.
State of Nature: A concept used in moral and political philosophy to denote a hypothetical condition before any state or society's existence. It is often invoked in social contract theories.