Does one decide to destroy a part of oneselves humanity - is there a decision to let it go? If not, how can that be punished? I think that a premeditated kill is just the grande finale, it demonstrates a piece of humanity that didn't sufficiently exist in the first place. I think the emphasis on this matter is somewhat messed up - the primary task of the society should be to try and make sure that missing piece gets developed (before its too late). Of course, its a lot tougher than putting people down.
That said, it is clear that humanity doesn't have the wit to get by without killing, any time soon - but pretending it to be just (in any case) will only hamper the progress towards that goal (if it is a goal).
And yet...then you've just made my point in a different way. Once it happens it's too late, so they have to be dealt with somehow.
Humans are not killers by nature. There is plenty of evidence to support this, starting with the fact that most of us never kill another human and going on to the fact that even extensive training to do just that does not always produce someone who can. S.L.A. Marshall proved the point pretty conclusively.
How has a rapist shown that death is the worst punishment?
He hasn't. That's confusing my argument based on the foundations of the US legal system with my personal beliefs. I grant they were in the same post, Kara, but I did delinate them into two seperate paragraphs and even marked the belief-based one for what it was. These are seperate arguments and seperate points.
What you're actually trying to do is claim that some crimes make someone sub-human in order to justify the death penalty. But the question then becomes who gets to decide who is human and who isn't?
See above.
More than that, there is a reason why the death penalty cannot be applied unilaterally by the judge, only recommended by the jury and upheld or rejected by the judge.
EDIT: I could take umbrage at the "claim" part too...I
know first-hand there are things that make someone subhuman, though we haven't actually touched on them here. In any case, it's not "crimes that make someone subhuman" in the sense you mean...
It's not a very rational thing to believe in the soul for an atheist, I suppose, but when an act has such an effect on a victim that it destroys something, or everything, of who they are, then I believe that things have progressed to the point where the perpetrator needs to be permanently removed. Until we develop Bablyon 5's Death of Personality punishment, killing them is pretty much all we have the toolkit for that.