Political Theory/Early Humanism
State of Nature Philosophy
During the mid 1600's there were two competing theories about political philosophy, but both began with the same idea. Imagine complete and total anarchy. People are free to do whatever they want at any time, with absolutely no government or authority controlling them. Two of the main philosophers of the time, John Locke and Thomas Hobbes, deemed this a "state of nature", but their theories went completely different directions from there
Hobbes and the Leviathan
Hobbes deduced that people would need someone to rule over them with an iron fist: a Leviathan from biblical times. People would constantly infringe on other's rights without a government, and he believed that a strong, powerful dictator-like figure could keep control over the masses the best in order to protect people from a State of Nature.
Locke and Social Contract Theory
Locke tends to get a little more attention when it comes to Natural Rights Philosophy. He thought that even in a state of nature, all humans possessed inherent rights: those to life, liberty, and property. He also believed something similar to Hobbes in that people would constantly infringe on one another's rights, and that they would end up living short, painful lives.
That is where they began to separate. Locke thought that the people would eventually naturally form groups that would agree to protect each other's rights in exchange for a few of their freedoms. This is the main idea behind social contract theory in modern politics like democracies. The idea that the government's power is derived from the people who support it, and therefore that the ultimate governing authority rests with the people of a nation-state was almost unheard of at the time, but is now used as a basis for most republics.
That is, of course, a very simple explanation of a very complex idea, and each has it's own intricacies, If you are interested in political science, reading Leviathan and some of Locke's papers are a must.