Prison as punishment is a 19th century humanitarian invention that was something of an advance on what preceded it. Although prisoners were held prior to trial, if found guilty they would be whipped, or branded, or have their nose slit, or ears cut off, or be fined or hanged. It was all a bit, well, Islamic. They wouldn't go back to just being locked up - which wasn't seen as any sort of punishment. Later we exported them - first to America, until a little local inconvenience there in 1776, and later to Australia. Eventually, just as the Second Enlightenment kicked in to end slavery, so it modified our approach to retributive justice. Jeremy Bentham got to work on his drawing board, and Her Majesty became the proud owner of the world's first Panopticon Prison.
Rehabilitation didn't arrive on the scene until sociologists started to turn up in the sixties, at about the same time as we stopped jailing buggers. By the nineties, we were being invited to view prisoners as victims; prison, we were told, was the inevitable destination of most 17 - 24 year old ill-educated but testosterone fuelled bastards from sink estates, and their 'criminality' was our fault, not theirs.
And now the Prison Governors' Association, a body riddled with the cancer of sociology, has called for all sentences under 12 months to be abolished. Never mind that Cameron has just called for magistrates' sentencing powers to be increased from 6 to 12 months. Never mind that this would remove the sanction of imprisonment from the courts that dispose of the vast majority of criminal offences. Never mind that those living next to neighbours from Hell will get no respite from persecution. The PGA are away with the fairies; completely out of touch with what we require them to do, which is to hold in prison for the term specified by the judge or magistrate those whom we have collectively determined must be so punished. Some sentences must, for fairness, be short and some long.
In Waugh's 'Decline and Fall' a liberal prison chaplain named Prendergast decides the best rehabilitation for a homicidal carpenter is to provide him with a full set of the tools of his trade. The prison landing is shortly rewarded with Prendergast's screams as the mad chippie saws his head off. The PGA would probably put it down as the exception that proves the rule.