Answer:
1. Sovereignty of the People: The source of all political authority lies in the people.
2. Separation of Powers: No government branch should have too much power, thus the legislative, executive and judicial branches should be separate and co-equal.
3. Checks and Balances: Powers should be divided among the three branches, so that no one branch has too much power.
4. Popular Sovereignty: All government power is derived from the people, who can change or abolish the government if needed.