This was no rationalization. The definition of insanity that you gave certainly does not invalidate my point. You are on a good track here. Asking what the definition of something is important. So now, define "right" and "wrong" in a way that does not involve your own set of values.

Beep... that doesn't work. You are certain that the killers can't distinguish right from wrong. How you come to this conclusion, I don't know. First of all, they could be simple murderers: those who know something is wrong, and yet still do it. If it was always insanity, then instead of full jails we would have had full assylums [sp?], but most people are found responsible for their own deeds.

The other, more sticky point is that "right" and "wrong" are in the eye of the beholder. We grow up on mostly humanist values, meaning that human life is sacred. Some people, however, believe that the most important thing in the world is honor, or the glory of the emperor, or the word of Allah. We grow up believing that freedom is important. Other people believe that order in society is more important than freedom. Others think that glory in battle is more important. There are many systems of values.

So if "right" is "to make the entire world believe in the word of [insert deity here]", and "wrong" is "to allow people who believe in other deities to live", those people can certainly tell right from wrong.

Catch them, prevent them from performing those atrocities - certainly. But we are doing it not because there is an absolute "right" and an absolute "wrong". In this way lies danger. We must do that because we believe that human life are sacred. Not because it's obvious. Because we can't believe anything else.