However, I cannot understand the absolutist position any more than I can understand the absolutist position on abortion: the world is just messier than that, and sometimes we do some things that might not be the morally ideal because the alternatives are morally more reprehensible. It seems to me that sometimes there are individuals who put themselves so far beyond the pale of tolerable behavior -- even tolerable criminality (tolerable in the sense that the punishment for it is limited) that they cannot be permitted to ever possibliy prey on society again. For me that militates for execution: it is certain and it avoids subsidizing the animal's existence. When we as a society face choices about the use of resources, I'm not willing to spend significant sums to house, feed and guard truly dangerous criminals. No one made them do the crime. I suppose an exaggerated sense of fairness might dictate announcing a head of time that murderers (without extenuating circumstances) would after a date certain no longer be tolerated, but the death penalty has been on the books and the criminals knew it was there.
'Cept he's not really an animal, is he?
I guess one could make an argument like military necessity, like we would have to kill Osama bin Laden because he is too dangerous to let live. But short of that, spending the money and applying the technology necessary to safely confine somebody for life doesn't seem too high a price to pay.
And, of course, life means life. In on your feet, out in a box,... life.