Contributor(s): Dr Anastasia Chamberlen, Peter Dawson, Professor Antony Duff | Societies take it for granted that we should punish those who commit crimes. Punishment for serious crime takes various forms in different areas of world and periods of history: caning, mutilation, death, exile, servitude, and imprisonment are all examples. But why do societies engage in this practice? What purpose does punishing serve? And does the punishment we find in modern societies do an effective job of meeting these aims? A leading philosopher, a decorated criminologist, and a prominent prison reform campaigner and ex-governor engage in a dialogue to answer these questions.