Prisons is not only about threat to others, its also about punishment. Someone could maybe kill a whole family, then after a year in prison have an "enlightenment", become religious, have regrets about the killing, and knowing himself that he won't do it again, he still deserves his full prison sentence!
That's moralizing. Punishment is something parents do to their kids or churches do to their congregants. I certainly understand why people strongly believe the prison system should be used to try to balance the grand metaphysical scales of justice, but I tend to think it should be used to make society safer and better.
Thinking that criminal justice should be about personal punishment, not social outcomes, is what leads to people being thrown in prison for selling sex or consuming drugs.
You're wrong. The whole system should be based on crime prevention, not punishment.
There should be better predictors of how likely a person is going to repeat the crime and keep him locked up for that amount of time. Also, predictors of how likely it is for someone to make their first crime, so it could be prevented in the first place.
I'm pretty sure that it's possible to predict future criminals from their Facebook data etc, and just send those people somewhere else where their environment matches their behavior.
