In response to the previous discussion on punishment, I think that maybe some problems are being overlooked here. If what we are concerned about is behavior mod, then it is being assumed that the loss of retributive punishment is simply going to eliminate only the vengeance. But this is far from clear. The end up retribution may result in less harsh punishments in some cases, but also perhaps harsher ones in other cases. I am inclined to think of retribution is an upper limit on punishment. We must give criminal at most as much punishment as they deserve, but we can't possibly give them all the punishment they deserve every time, and it would make us far worse people if we did. If we thought that we ought to a serial torture killer (BTK, for example) suffering equivalent to that which he inflicted on his victims, then we would be punishing people in ways that no civilized society could punish them.
However, once punishment is reduced to behavior modification, then we could punish people a la Minority Report who might become offenders, we could end up punishing innocent people if we think their punishment will result in better results for society.
I hate to say it, but it's all in Lewis, it's all in Lewis.