So you're trying to say that there's no universal standard for human decency...

[Well, that's...

...are you stupid or something?]

If you kill someone in front of a group of people, even if none of them know each other, there will generally be horror and outrage among the group - those that aren't shocked by it are seen as abnormal unless they can explain why, and they'll usually still be seen as really messed up. Also, countries who otherwise can't agree on anything generally all have laws against murder, and agree that even in times of war attacking civilians is a war crime. That implies some sort of basic standard - "killing innocent people is bad" - that almost everyone can agree on.

This works for other laws as well - even if they don't get upset until it's happening to them, almost everyone will agree that taking what isn't yours from someone else isn't fair. Whether they think it's right or understandable is another matter, it's almost universally acknowledged that it's not fair.

So no, there are some things that are accepted as human decency and some that aren't, and those things aren't arguable.