> The additional 10 years is 10 more years where they can't hurt innocent people. The justice system exists for the benefit of society and innocent citizens, not criminals.
By this logic we should just never release them. Should we keep the 80% that would not reoffend locked up to prevent the 20% that would from doing so?
Should we increase the sentence from 10 to 20 years to make that ratio 60% to 40%? Then we prevent more crime, and the would be criminals are off the street longer.
Maybe if we decrease the comfort of the cells and general state of the prisons, we can get the rate to 20% to 80%? Then we can practically say we’re justified to keep those 80% off the street.
> Why would you ever assume that? Punishments absolutely have a deterrent effect.
Because most people aren’t stopped by the deterrent effect. It’s perfectly possible the net negative effect of locking people up for a longer time is larger than the extra deterrent effect [1].
[1]: https://nij.ojp.gov/topics/articles/five-things-about-deterr...