Locke's political theory was founded on social contract theory. Unlike Thomas Hobbes, Locke believed that human nature is characterised by reason and tolerance. Like Hobbes, Locke believed that human nature allowed people to be selfish. This is apparent with the introduction of currency. In a natural state all people were equal and independent, and everyone had a natural right to defend his "Life, health, Liberty, or Possessions".[33] Most scholars trace the phrase "life, liberty, and the pursuit of happiness," in the American Declaration of Independence, to Locke's theory of rights,[34] though other origins have been suggested.[35]
Like Hobbes, Locke assumed that the sole right to defend in the state of nature was not enough, so people established a civil society to resolve conflicts in a civil way with help from government in a state of society. However, Locke never refers to Hobbes by name and may instead have been responding to other writers of the day.[36] Locke also advocated governmental separation of powers and believed that revolution is not only a right but an obligation in some circumstances. These ideas would come to have profound influence on the Declaration of Independence and the Constitution of the United States.