There are three purposes for prison. First, prison separates criminals for the safety of the general population. Second, prison is a form of punishment. Third and finally, the punishment of prison is expected to rehabilitate prisoners; so that when prisoners are released from prison, these ex-convicts are less likely to repeat their crimes and risk another prison sentence. The logic for capital punishment is that prisons are for rehabilitating convicts who will eventually leave prison, and therefore prison is not for people who would never be released from prisons alive.