I dont think that we will ever find an answer to this often posed question. We have seen it posed in one form or another both here and at the teachers site on many occasions. It is a question that cuts right at our human values and affords everyone who offers thier opinion on this topic to be God for a day, as it were.
While I acknowledge that my stance on this issue can easily be argued as being idealistic or maybe even altruistic my advocacy is borne of the general question and is a conclusion that I arrive at without looking at some of the horrific details of any one particular crime that posters offer in support of thier arguement.
It is true that there are a great many criminals for whom there is no hope of rehabilitation as thier twisted approach to life and the lives of others is beyond any current corrective methods. In cases such as these, are we to simply give up and remove them from the planet and in doing so end the problem? In my opinion, I think not, as it has indeed not ended the problem because there will be another such case to deal without doubt.
Are we, as a human society, to exhaust all avenues of assistance for these twisted souls and then throw our hands in the air when no solution can be found and simply execute them, often in a cruel and very violent way?
Again, I think not as in doing so, we are saying that we have no solution.
All this is assuming that the evidence is complete and final and that no more remains to be discovered either before or after thier execution. If for no other reason than past experience has shown that new evidence does come to light, after the fact, and innocent folk have been killed based on incorrect evidence, we, as a race, should never level death as a punishment because we are human and, as such, are prone to error.
Life, no matter how turgid and ugly or twisted in the eye of the sane, is everything.