So you agree that there is some degree of punishment that is acceptable for violent criminals? And I don’t think any serious person thinks jailing forever is the only right response to violent crime; the much more defensible position is “jailing until they are rehabilitated”, but this isn’t about punishment, it’s about protecting society. As it happens, rehabilitating prisoners is extremely hard and expensive, so sometimes we have long sentences and other times we let violent offenders out to further victimize their communities.