D'oh! I haven't got time to read it properly yet, but it would seem that despite theoretical "unfairness" that Francesca rails against, the scheme has stood in good stead for the 104/67 years of operation. It would seem that what is needed is reasonable readjustment, rather that outright abolition.
Specifically with respect to the state pension and public sector occupational pensions where current contributions only cover current outgoings.......
From my perspective the unfairness is that today's NI and tax contributors pay for the current set of retirees. Because of a much larger number of retirees and a proportionally much smaller number of workers means that today's workers are paying a greater proportion of their salary to support retirees than in the past (and looking at demographics, the situation is likely to get worse).
IMO FrancescaR is correct that this is a transfer of wealth from working age people to the retired. When the currently retired people were starting their careers, there were twice as many contributors and benefits were significantly lower in real terms. They are getting maybe three times the benefit than they have paid for. There comes a point in time where such schemes become unaffordable especially when trying to square the circle of reducing government expenditure as a % of GDP and raising pensions in real terms.
We don't know that the current scheme has stood us in good stead (at the moment the NI contributions - after the NHS payment has been made - cover somewhere between 1/3 and 1/2 of the current liabilities, the remainder being made up from general taxation) but I agree that there needs to be revision.
The defined benefits route puts all of the risk and liability onto the employer, in this case the UK taxpayer. If we keep a defined benefits model then that risk remains with the employer (even if contributions are increased and/or benefits are reduced (by some combination of averaging rather than final salary, being able to buy fewer n'ths of salary or having to contribute for longer) and people currently working will bear the brunt of funding those pensions.
Defined contribution schemes aren't a panacea either. The employer has abdicated responsibility and the employee is at the mercy of the pension find manager for better or worse.
The trouble is that I cannot come up with a fair and reasonable shared risk model where both employer and employee have skin in the game.