Tradition and common-sense assume that ethics is about trying to determine what is objectively right or wrong, so that we can try to do what is right.  please choose one : psychological egoism, cultural relativism, ethical subjectivism, error theory, and expressivism.

Pick whichever of these theories you think provides the strongest challenge to traditional ethics, and then explain what the theory claims.

Demonstrate how this theory could be used by applying it to an example you create (preferably, not an example already used in the textbook or lectures).

In your view, is there a good response to the challenge posed by this theory, or must we accept that the traditional, objectivist approach to ethics is incorrect?