Thomas Hobbes

Hobbes proposed that in the face of chaos (no law or order), individuals would do whatever was necessary to fend for themselves and would act selfishly and harmfully towards one other. He also argued that these natural results could be avoided by setting up a government.

http://www.thomas-hobbes.com/works/leviathan/

State of nature is a philosophical concept originating with Hobbes. Paraphrased, the term is used to describe the hypothetical condition of humanity prior to the existence of government. It would be the period before any rule of law existed.

http://en.wikipedia.org/wiki/State_of_nature

Jean Jacques Rousseau

Rousseau’s writings influenced the thinking of the American founding fathers, in particular his discussion of social contract theory.

In his Discourse on the Inequalities of Men (1754) and Social Contract (1762) he explains that people entered into a social contract among themselves, establishing governments and educational systems to correct the inequalities brought about by the rise of civilization.

They submit to the authority of the general will of the people and ensure obedience because they, themselves, are the authors of the law. As translated by G. D. H. Cole at http://www.constitution.org/jjr/socon.htm, Rousseau writes the following in The Social Contract:

“Finally, each man, in giving himself to all, gives himself to nobody; and as there is no associate over whom he does not acquire the same right as he yields others over himself, he gains an equivalent for everything he loses, and an increase of force for the preservation of what he has."

If then we discard from the social compact what is not of its essence, we shall find that it reduces itself to the following terms:

“Each of us puts his person and all his power in common under the supreme direction of the general will, and, in our corporate capacity, we receive each member as an indivisible part of the whole.”

John Locke

In his work of political philosophy, Two Treatises, Locke covers a variety of themes, including the defense of resistance to tyranny. He believed there was a natural equality among all men.

Locke is a believer that, where there is no legitimate government, there is anarchy. Even in this scenario men are not free to do whatever they choose. "The state of nature has a law of nature to govern it, which obliges every one: and reason, which is that law, teaches all mankind, who will but consult it."