You have suggested two reasons why ethical relativism is plausible.

• Relativism offers an explanation for the diversity of moral judgments and fundamental moral principles.
• Many people believe that there is no proof that a single set of principles is superior to others or true in some important sense of 'true.' Indeed, as Ayesha pointed out, it isn't clear what it means to say that a principle like "Do not kill innocent human beings" is true. We do not usually say that commands are true or false.

John suggested that people often accept the second view because various proofs of this or that principle seem to fail. You mentioned several kinds of proof:

• scientific proofs
• metaphysical proofs showing that values are somehow built into reality
• conceptual proofs showing that values are implied by some of our basic concepts
• theological proofs showing that values are given by God

If all of these fail, then ethical relativism seems to be left standing by default. Perhaps that is true, but it is also important to be clear that not all philosophers agree that these approaches are doomed. These are tough issues. It may seem obvious that none of these proofs can succeed, but perhaps for that very reason we should question it. Do we really know that these proofs are hopeless?

Let us assume that none of these proofs succeeds. Then what?