Not the whole point. Surely you'd want some attempts at rehabilitation? Also you'd like to prevent re-offending.
Anyway. Interesting though this little side discussion is into the reasons for prisons, I think we should clear the way for the deluge of posts on Nick Griffin's imminent appearance on Question Time.
I fear most of us will be disappointed - he seems pretty media-savy. I think he'll raise lots of sensible objections to the current system as a way to show the public how the BNP represent their concerns. I suspect he'll neatly side-step any direct questions on, for example, the BNP's policy of repatriation.