But why do we punish? What is the logical reason for punishing?
There are two:
1) to prevent people commiting crimes.
2) to prevent people commiting crimes again.
Ultimately yes, prisons are about punishment. But the punishment is there to lower/prevent crime. We have prisons these days to maintain order, not just for revenge on people for being bad.
I absolutely agree, sentence should fit crime. Stealing a loaf of bread should not be the same as killing your neighbour and ****ing her corpse, or pounding her car.
I'm not saying there shouldn't be prisons, I'm saying this call every few years for longer and longer sentences is self-defeating and had been proved over and over again all over the world to not be effective in lowering crime. There is actual data that it doesn't.
If you get five years, or fifteen years in jail for beating someone badly, at that point there is a diminishing set of returns on preventing crime. Same with murder, I can't imagine many people would say "20 years in jail isn't so bad. I'll kill this guy." But then reconsider for thirty years.
Incidentally as an interesting aside... prisons, AS a punishment, is actually a fairly recent phenomenon before the late 1700's prisons were where you kept people before you decided how to punish them. Prisons weren't actually built with the intention of keeping people locked up as a punishment originally. It's where you kept people before putting them in the stocks, or hanging them, etc.