[lehmannro]

Depending on your standards, you can justify absolutely anything. There is nothing that is inherently right or wrong -- perhaps something that is right or wrong in most views.

Our standards have changed, too -- not even a century ago, holocausts were considered absolutely appropriate (even by scientists!).

[sant0sk1]

No. Despite your opinions, and your best efforts to redefine good and evil, there are things which are inherently wrong. Murder is one of those things. All humans know murder is wrong, whether they admit it or not.

[donw]

Right, so the Samurai, who would randomly cut the heads off of people they didn't fancy, knew they were doing something wrong, and yet were totally okay with it? Beheading a few peasants was, after all, the right way to test out a new sword... there's even a term in Japanese for it: Tameshi-giri.

Plenty of societies, both ancient and modern, have legalized, or even encouraged, what we define as 'murder'.

And note that I'm not arguing that murder is acceptable; rather, that the definition for it changes so much between societies as to make the statement "Murder is wrong in all human societies." a completely meaningless phrase.

A likely explanation for the prohibition against the killing of other humans is strictly pragmatic: Societies where members can kill each other freely will self-destruct. This has nothing to do with 'murder being wrong', as much as free homicide not being a very stable evolutionary path.