The ability comes from what is socially constructed. Morals evolve over time, unfortunately. Murder is only wrong because society says it is wrong. Once society accepts it as a norm, murder could become alright. But because it is so extreme, it is not. Homosexuality was once regarded as a perversion but is now widely accepted as an acceptable lifestyle because society says it is "okay", they don't want to interfere with the private lives of others.
God put the blueprint for living right there in front of us.
Afghans say enslaving women is okay in their culture. And according to your criteria, they are right as culture defines morality. Where do universal human rights come from - can't be cultural. What are they?
Homosexuality was once regarded as a perversion but is now widely accepted as an acceptable lifestyle because society says it is "okay", they don't want to interfere with the private lives of others.
You have just stumbled into the "is-ought fallacy." Just because certain moral behavior is observed - that says that doesn't require that people OUGHT to be doing it. A conclusion about the nature of morality cannot be made from mere observation of different cultural moral practices. Morality is not judged empirically.
Actually, this is incorrect. That would be a "socialistic" view point. The individual has a sovereign interest in his own survival, so he doesn't need society's instruction as to whether he has a right to defend himself. He can, in fact, figure that out from introspection alone.
Morality tells us how we may interact. By first principles we always retain the right of self-defense. We can always adjudge an unprovoked assault on ourselves as "wrong" or "immoral". Whether society agrees or not is irrelevant.
Yes, society can empower or align with natural rights, such as self-defense, but it can't simply whim them out of existance.
Well, I have to disagree with this. Murder and other detrimental behaviour like stealing undermine the trust that the members of a society put in each other.
Societies are fault tolerant systems to a cerain degree but if such a behaviour becomes to common they disintegrate. So if a society adopts murder you end up with individuals that regard each other as enemies thus fighting each other to the death. Therefore one can say that these individuals no longer form a society.