Well first of all, that's far from immediately clear. How do you know? It's dangerous to apply this label to someone, I believe. I think you'll find many decent individuals alive today who broke the law in the past and were deemed by some as forsaken.

But if somehow you were able to determine without fault, or with so little fault that it's somehow acceptable that someone is truly not able to change. Well, what about a dog that can't be rehabilitated? Do you torture him? Of course not. (not saying you're implying this but revenge was the root of the discussion).

You either kill him, or let him live a normal life with few luxuries, separated from those who he can harm.

So what about killing. Well we know a few things. For one, innocent people have been killed, but killing is a uniquely permanent action. So for that reason alone we ought to be skeptical towards capital punishment, and preferably outlaw it completely in my opinion. And secondly, it's not a dog, it's a human being, and killing humans says something about your society, about how human life is treated, how a legal system leans on notions of revenge, and shows a failure of finding good solutions, a loss of hope and perhaps even basic humanity.

That may sound like a load of crap, but when we reduce our sense of justice to the harshest punishment we can imagine that permeates throughout the rest of society in more insidious ways. It creates this sort of cognitive dissonance (he's on death row, so he must deserve it) that opens up discussions on even harsher and more barbaric punishments (torture).

In short, I don't think the death penalty is a great solution.