Social contract
Social contract is a concept in political philosophy as a justification for the existence of state, or government, by the consent of the people among themselves and/or with the governing authority, in a collective agreement analogically called "contract". One of the earliest proponent of social contract theory was Thomas Hobbes, who espoused monarchical absolutism. However, the concept was then used by different theorists such as John Locke, Jean-Jacques Rousseau and Immanuel Kant to arrive to their conclusion supporting different forms of liberal or democratic state.
In the modern era, social contract was revived again by modern American philosopher John Rawls. Greatly influenced by the Kantian version of social contract, Rawls rebranded it into his own version and named it "origional position" in his A Theory of Justice.