I have never heard one politician use the word "evidence" so persistently, and so misleadingly, as Andrew Lansley defending his NHS reforms. As he repeatedly claims that the evidence supports his plan, let's skim through what we can find on whether GP consortiums work, the benefits of competition and the failures of the NHS.

Are GP consortiums better than primary care trusts (PCTs) for commissioning? There have been 15 major reorganisations of the NHS in 30 years. We've had GP fundholders, GP multifunds, primary care groups, PCTs, family practitioner committees, purchasing consortiums, and more. After all this change, lots of data should have been gathered on the impact of specific strategies.

In reality, few were properly studied. Here are four papers on GP fundholding, which is broadly similar to Lansley's GP consortiums. Kay in 2002 found it was introduced and then abolished without any evidence of its effects. In 2006 Greener and Mannion found a mix of good and bad, but no evidence that it improved patient care. In 1995, Coulter found nothing but gaps in the evidence and no sign of any improvement in efficiency, responsiveness or quality. Petchley found there was insufficient data to make any judgment. Lansley says he is following the evidence. I see no evidence to follow here.

Next, competition. Lansley has repeatedly denied that he is introducing competition on price. This is disturbing behaviour: his bill explicitly introduces price-based competition, it's in paragraph 5:43 of his NHS Operating Framework.

Does variable-price competition work in healthcare markets? It's hard to measure, but the evidence even on fixed-price competition – where you compete on quality – is mixed. There are various ways to assess it: often people choose an outcome – such as the number of people who survive a heart attack – and compare this outcome in areas of more intense or less intense competition. Sometimes competition makes things worse, sometimes better.

Working from first principles, markets where people compete on price as well as quality will probably make quality worse, because prices are easy to measure, while quality is not. The evidence seems to support this theory. The introduction of variable price competition in New Jersey in the 1990s was associated with a worsening death rate from heart attacks, while in the UK, stopping variable price competition was associated with improvement. It's hard to measure either way, but the "evidence" does not support Lansley here.

Last, there is the justification for reform. Both Lansley and Cameron overstate our mortality figures to claim that the NHS is failing. Everyone wants more improvement, but money does not produce an immediate and visible reduction in mortality from one thing. Interventions take time to have an impact, especially on things that kill you slowly, and treatment isn't the only factor affecting how many people die of something. But to take just two things, mortality from cancer has fallen every year since 1995, and heart attack deaths have halved since 1997.

The government claims that our rate of death from heart attacks is double that in France, even though we spend the same on health. Health economist John Appleby instantly debunked this claim in the BMJ, and his piece will become a citation classic. From static 2006 figures in isolation the government is right: but the trajectory of improvement in the UK is so phenomenal that if the straight line continues – as it has done for 30 years – we will be better than France by 2012.

I'm not in favour of, or against, anything here: all health service administrative models bore me equally. But when Lansley says all the evidence supports his interventions, as he has done repeatedly, he is simply wrong.

His wrongness is not a matter of opinion, it is a fact, and his pretence at data-driven neutrality is not just irritating, it's also hard to admire. There's no need to hide behind a cloak of scientific authority, murmuring the word "evidence" into microphones. If your reforms are a matter of ideology, legacy, whim and faith, then, like many of your predecessors, you could simply say so, and leave "evidence" to people who mean it.