We know that plenty of learning does in fact take place in prisons. Why else should they be called "Universities of Crime"? New inmates (nearly always young men) are speedily introduced not only to new forms of crime and more sophisticated techniques than the ones which got them put away in the first place, but to a brutal institutionalised sub-culture. With the prisons more overcrowded than ever, who can doubt that many prisoners come out even worse than when they went in?
Prison can be said to have four main functions: deterrence; rehabilitation; protection of the public and retribution. Apart from the fact that individuals do find it hard (though not impossible) to continue their criminal activities while actually locked up, the only function which our system now seems to be fulfilling is the last one - retribution.
Where is Number 10's much-trumpeted social exclusion unit in all this? Quite rightly, the Government is trying to create cross-departmental policies to address the needs of those who are socially or politically marginalised: the unit's first report, on exclusion from school, comes out next week.
But no one seems to be focusing on prisoners, who are apparently expected to exist in some sort of developmental limbo until their release. If intervention is supposed to be targeted on those who need it most, surely no one could be more excluded from mainstream society than someone who is in jail.
The shameful state of our prisons speaks of anything but a fresh start. Are we going to carry on packing them to bursting, barely attempting to train, educate or rehabilitate their inmates? Could it be that the Government is so in thrall to the voters of Middle England that it will tolerate this antiquated, vengeful regime indefinitely?
The one bright spot on the horizon is the New Deal, which this week took one more step towards becoming a reality (see page 4). We know that young people who played truant from school or were excluded, or spent their formative years in care, are the ones most likely to be in jail.
So it is good news that 11 prisons and young offenders' institutions are taking part in the New Deal, in the hope of improving the job prospects of almost 2,000 young people.
But as well as a couple of months of basic literacy and numeracy, and help in job-seeking skills, prisoners need a real introduction to the whole world of self-improvement through education. New technology gives us a marvellous opportunity to develop innovative learning packages for those who missed out so badly first time around; it is no longer necessary to gather people together in a room in order to teach them - but prison education, by and large, has yet to reflect this fact.
Maybe ministers fear that equipping jails with computers for lifelong learning would result in tabloid headlines featuring the dreaded "h" words:
"holiday camp" and "hotel". But surely they could justify spending a bit of money on a system which would send offenders back into society better-educated - and better people - than they were when they left it. In the long run, Middle England would benefit too.