The United States is based on abstract principles which must be constantly reinterpreted and renewed in practice. That is the beauty of the American experiment.
These principles include:
1. The Rule of Law
2. Democracy: Rule by will of the people.
3. Freedom: Freedom from tyranny, freedom of thought and speech, freedom of religion, etc... .
4. Human Rights: People are endowed with unalienable rights the state cannot take away.
Unfortunately, corruption and power have tried to subvert these fundamental principles on which the U.S. and the free world is based. It doesn't mean we should give up. Just the opposite, we must strive even harder to obtain them. Perfection is the enemy of the good.