Is morality objective? In other words, are there moral obligations that apply to all rational beings?
Consider some theories that deny this, and some reasons why those theories fail (cf. James Rachels, Elements of Moral Philosophy, third edition, 1999): Nihilism: Morality is an illusion; there are no moral obligations. This would mean that there s nothing inherently wrong with something like cruelty, which seems strongly counterintuitive. A nihilist would have no grounds upon which to argue rationally against someone else who wanted to harm him or her just for the fun of it. Psychological egoism: We can t avoid being selfish, hence there s no point in reasoning about ethics. Selfishness can sometimes masquerade as altruism, to be sure. But PE is too sweeping and reductionistic: even if showing compassion toward others makes you happy, that isn t necessarily why you do it. Even if we are sometimes selfish, we can have unselfish motives, too. Normative egoism: I have no moral obligations to anyone else; only my interests count in deciding what I should do. But if others interests are sim