1. John Locke
Locke's political theory was founded on social contract theory.
Locke believed that human nature is characterized by reason and tolerance.
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.” 
Most scholars trace the phrase "life, liberty, and the pursuit of happiness," in the American Declaration of Independence, to Locke's theory of rights, though other origins have been suggested.

2. John Locke
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.
Locke also advocated governmental separation of powers and believed that revolution is not only a right but an obligation sometimes.
These ideas would come to have profound influence on the Declaration of Independence and the Constitution of the United States.

3. Montesquieu
Montesquieu's philosophy of history minimized the role of individual persons and events. He expounded the view in Considérations that each historical event was driven by a principal movement:
“It is not chance that rules the world. Ask the Romans, who had a continuous sequence of successes when they were guided by a certain plan, and an uninterrupted sequence of reverses when they followed another.”
“There are general causes, moral and physical, which act in every monarchy, elevating it, maintaining it, or hurling it to the ground.”
“All accidents are controlled by these causes. And if the chance of one battle—that is, a particular cause—has brought a state to ruin, some general cause made it necessary for that state to perish from a single battle.
In a word, the main trend draws with it all particular accidents.

4. Montesquieu

5. Montesquieu
Montesquieu believed that all things were made up of rules or laws that never changed.
He set out to study these laws scientifically with the hope that knowledge of the laws of government would reduce the problems of society and improve human life.
According to Montesquieu, there were three types of government: a monarchy (ruled by a king or queen), a republic (ruled by an elected leader), and a despotism (ruled by a dictator).
Montesquieu believed that a government that was elected by the people was the best form of government. He did, however, believe that the success of a democracy - a government in which the people have the power - depended upon maintaining the right balance of power.

6. Montesquieu
Montesquieu argued that the best government would be one in which power was balanced among three groups of officials.
He thought England - which divided power between the king (who enforced laws), Parliament (which made laws), and the judges of the English courts (who interpreted laws) - was a good model of this.
Montesquieu called the idea of dividing government power into three branches the "separation of powers."
He thought it most important to create separate branches of government with equal but different powers. That way, the government would avoid placing too much power with one individual or group of individuals. 
He wrote, "When the [law making] and [law enforcement] powers are united in the same person... there can be no liberty."
According to Montesquieu, each branch of government could limit the power of the other two branches. Therefore, no branch of the government could threaten the freedom of the people.
His ideas about separation of powers became the basis for the United States Constitution.