This seems like a very straight forward question, that I would bet most americans would get wrong. The purpose of a prison is supposed to be to remove from society people who cannot be rehabilitated. Thats it. It is NOT supposed to be punishment for a crime. First of all positive reinforcement works far better than negative.
I really want to continue with this post. I read some Howard Zinn last night that got me fired up. Prisons are terrible terrible things. Yes any civilization is going to need some, a few. But when a small town like mine 30,000 ppl, has count 'em TWO maximum security prisons its a sign that something is wrong. Yeah most of the prisoners aren't from here, many come from The City, and many times their families follow which many residents blame for the town going to shit. But thats off topic, the problem is our justice system seems to have forgotten or maybe simply never learned about human behavior. If you have a person with a drug problem who robs a store to buy drugs, the solution isn't to punish them for the robbery its to get them off drugs. Which leads to a bigger issue of giving people enough hope so that they don't want to numb themselves with drugs. Thats just a quick example, our drug policies are unconscionable thats all there is too that. But even more serious criminals need to be taught a better way, they need education, they need a chance to do better legally. Few people want to be criminals but many people will go to that if they feel they have no other choice. This isn't even getting into the massive inequality between the rich and the poor.
The quick of it is that the US has more prisoners than any other country in the world, and it doesn't matter if you weight it for population or not. Think about that China has a billion people more than us and less of them are in jail, I'm not saying we should emulate China but they must be doing something better.
I'm spent. Too much bitterness at the political world of late and not enough good going on elsewhere.