Alan Maynard is professor of health economics at York University.

With the general election a likely 18 months away, and if the economy remains robust, it is probable that one of the main areas of political debate will be the NHS.

The experts in destabilisation are gathering. The British Medical Association, ever anxious to improve the pay and conditions of its members, has announced another inquiry into future NHS funding. This is super for BMA members as it diverts attention from the quality and efficiency of care and from tough issues like accountability.

The choice of funding options is as obvious as it is clouded by pundits.

Basically, all expenditure is funded by households, which can be 'relieved' of their resources to fund healthcare by taxation, social insurance, private insurance or user charges.

Taxation is generally progressive. The rich pay more than the poor.

Social insurance is disguised taxation, used on the Continent - often because payment of direct taxes is regarded as a sin in places like France - and is a proportional tax; the rich and the poor pay the same proportions of their income.

Private insurance, because the rich tend to be fit, can be regressive - ie the less affluent pay a higher proportion than the rich. Also, many poor people cannot afford private insurance, and they end up with state provision in mini-NHSs - for example, Medicare in the US. Private insurance can be seen as an attempt by the rich to dump the poor into inferior care while they buy Rolls Royce (but often ineffective) care from insurers who give their members cost inflation and inefficiency.

The latter can be seen in the US, where 'managed care' has produced modest short-term efficiency gains followed by renewed cost inflation.

Of course, such inflation is one reason why doctors and other providers like the pharmaceutical industry favour private insurance. For them, more expenditure equals more income.

Both the private and public sectors have user charges. These are a tax on the ill and, to the extent that the ill are old and poor, they are a tax on the poor.

Often the gurus who advocate user charges (the BMA, for example) argue that they reduce 'unnecessary demand'.

This argument has dubious validity. Patients make the initial decision to use healthcare, but decisions to use healthcare resources are usually taken by doctors.

Doctors, in primary care and in hospitals, decide about treatment and, if there is 'unnecessary demand', it is caused by them, not by the patients. To tax patients with user charges to curb doctors' inefficiency is neither logical nor efficient.

Solutions to funding crises are, in principle, easy. Decide who is to carry the burden of expenditure (the rich or the poor, and to what extent? ) and note that tax finance gives you parsimony and cost control, and private finance gives you extravagance and cost inflation.

These are stark public choices that have always existed. The risk is that the BMA and other advocates of changes in finance will be less than explicit about their motives and will exploit public concerns about the NHS to change funding arrangements to their advantage.

The current NHS 'crisis' is a product, first, of parsimonious Conservative spending plans, meekly adhered to by a government whose sole concern is re-election, and second by Blair's campaign to make the NHS modern and dependable. The motivation for such changes is sensible and appealing to the public. Unfortunately, you cannot adopt such an ambitious reform programme without spending more to oil changes in the delivery of healthcare.

The fundamental issue is how to ensure that finance is spent well to improve the health of the population. Health secretary Alan Milburn accepted at the National Institute for Clinical Excellence conference in Harrogate in December that rationing, in the sense of prioritising patient groups, was unavoidable. This political acceptance is overdue.

But are the politicians prepared for the next step? This will involve the 'hard choices' Mr Blair makes much of.

Let's use some recent examples. Lord Winston's attack on Labour NHS performance should have been countered with public discussion about whether funding in vitro fertilisation treatment should be abandoned to give mobility and sight to elderly people by investing in orthopaedics and ophthalmology.

The inquiry into the failure to treat the Leeds woman with cancer of the oesophagus might have addressed two related issues. First, even if the number of intensive-care beds has increased, what are the health gains? Most patients in such beds are often aged over 70 and receiving 'heroic' care, often of dubious cost-effectiveness. Second, treatment of the oesophagus in elderly patients is usually of limited success. Is it sensible to delay death and produce additional months of poor-quality life at high cost?

Other elderly people would prefer hip replacements and cataract removal.

Such choices should be explicit and debated publicly. Instead, we have a demented and ill informed media which focuses on individual shock-horror cases and neglects the relevant social issues of who should be prioritised for what and when. As a society we permit human experimentation, usually with inadequate evaluation, with unproven high-tech medicines whose costs deprive other efficient NHS activities of much needed investment.

Medical practitioners admit this state of affairs, but do not challenge their peers. The politicians and the media consult medical professionals as if they are neutral and well informed arbiters of what needs to be done. Such medics usually pursue self interest rather than the needs of a society which wants proven healthcare interventions provided by accountable professionals.

The self-interest and political preferences of providers should not determine how the NHS is funded and, more importantly, how healthcare is provided.