I am sympathetic to your perspective, but this ignores any deterrent effect, which is probably very hard to measure.I don't think there's ever been any evidence that punishment ever does anything effective.
I disagree. I'm not advocating an elimination of a correctional system, just a revised one. Mass incarceration of overwhelmingly poor, minority, non-violent offenders to long sentences isn't a system that works as it should. You're still going to have a prison system, but one where it effectively attempts to address underlying issues. If a violent criminal is put in the system, is it because of gang ties or mental illness? Is it a result of being forced into a gang from a young age? Is it a failed emotional maturity? Etc., etc. If you have somebody in for, say, assault with a deadly weapon, they should be targeted differently than a person committing petty theft. Additionally, reducing our very bloated sentences won't affect the overall deterrent idea; however, are we convinced that the system we have now is a convincing deterrent?