Philosophy

Ethical systems are similar to mathematical systems: Both are based on axioms -- statements considered to be true for which no proof is given. You start with a belief, "The greatest good for the greatest number" or the Stoic view that the greatest good is contentment and serenity or the ancient Chinese view which bases the moral worth of an act on how it contributes to the social harmony of the state and so on; you then see how you can develop an ethical system from it.

Some time ago, I was having an argument with a follower of Nietzsche, who was claiming that all ethical systems were "lies". I suggested that Aleister Crowley's "Do what you wilt is the whole of the law" is the logical consequence of such an attitude. If you reject all existing ethical systems, you must replace them with something. If you don't, you are left with nihilism as a default. Nietzsche called for a mythical Übermensch to make everything well; since he said that God was a myth, he was simply replacing one myth with another. In other words, he replaced ethics with nothing, so everything is morally acceptable.