What should society do when that conclusion is appropriately reached?
What does this refer to? It's illegal to kidnap people, if caught you'll get sent to prison for it.
The GP is trying to say that the whole notion of incarceration is barbaric, and that future generations will look back on it just like we look at, say, stokades.
I guess this is where the fundamental disagreement is located. I don't see anything immoral about locking someone up for committing certain crimes any more than its immoral for a parent to confine a child to a room or take away something according to the "crime".
But the thing about prisons is that they aren't good as a punishment, either. Indeed, they came about as a supposedly "corrective" alternative to the more punitive approach. In practice, to punish someone by locking them up, you have to make the terms so long that the effects linger in their lives long after. Furthermore, locking random people up with career criminals for long periods of time is a wonderful way to turn them into the same.
If we really just want to punish people, let's bring back corporal punishment and be done with it. Ah, but that's considered barbaric - and yet somehow locking someone up for years is not?..
What is the alternative? If someone kills someone in cold blood do you just let them roam free? You could argue that certain crimes don't warrant certain levels of punishment but incarceration /generally/ seems necessary.
Would this work for someone like Stalin? No, I don't think so, so I don't agree entirely with GP.
There are more crimes and pre/potential crimes than just violence and murder. We even treat some innocent people as guilty by locking them up. At least we wouldn't have innocent people in cages if there were no cages. Perhaps restitution or weregeld could be a substitute for theft or assault. But I strongly doubt that putting people behind bars does much to improve their lives or the ones they've affected in the overall vast majority of cases.