1. Montesquieu: Separation of powers and checks and balances
The French political philosopher Baron de Montesquieu is most remembered for his work called The Spirit of the Laws (1748), in which he established and promoted the idea that the government should be separated into three different branches: the legislative, the executive, and the judicial. All of which should rule under the law and must check and limit each other’s power in order to prevent corruption or abuses of power (Checks and balances).
2. Voltaire: Freedom of religion and separation of church, state
The French philosopher Voltaire advocated for the freedom of religion and speech, and the separation of church and state. And as a deist, he also supported the toleration of other religions and ethnicity and didn't agree in people's fanaticism, idolatry, and superstition. These ideas were a great influence on the First Amendment of the U.S. Constitution.
3. Rousseau: Belief in democracy
The Genevan philosopher Jean-Jacques Rousseau believed that a perfect government was one ruled under a direct democracy in which all adult, white male citizens could participate and decide the content of the laws and all the measures that affected them.