When I first heard about Sushi in the early 2000s, like many others, I found the idea of eating raw fish very strange. When a friend urged me to give it a try, I flatly refused.

– ‘Why on earth would you want to eat raw fish?’, I asked. ‘It makes no sense. Fish is for frying, cooking or baking. You wouldn’t eat raw meat either.’

– ‘But you do eat raw meat’ my friend objected. ‘Just the other day, I saw you stuff yourself with Hackepeter [a form of seasoned minced pork meat, as raw as raw can be]. And you eat smoked salmon, which is, sort of, raw fish as well.’

Luckily, I had a highly sophisticated killer argument on hand: ‘But…that’s different!’

I can’t remember what ridiculous post-hoc rationalisation I came up with, but I’m sure I made one up on the spot. We always do. Unfortunately, we do it especially in political debates. ‘But that’s different’ almost always means ‘X is not principally different from Y at all, but Y has always been around while X hasn’t, so X makes me uncomfortable while Y doesn’t. And don’t ask me to explain why, or I’ll scream’.

The but-that’s-different argument has featured heavily in the responses I have received to my new paper, Health Check: The NHS and Market Reforms, in which I make the case for building on Labour’s quasi-market reforms, and allowing much greater involvement of the independent sector in healthcare. NHS purists like to think of healthcare as an island of socialism within the neoliberal dystopia of modern Britain. To them, the health sector is like a serene little church in the middle of a red light district, a sanctuary of higher moral principles that refuses to be tainted by all the corruption around it.

But the NHS has never been as insular as its worshippers would like to see it. The private sector and the profit motive have always played a role in healthcare provision. For a start, even the most devout NHS puritan would probably not argue that the NHS should produce its own stationery and its own office furniture (which, if you follow it through, would also imply that the wood used for NHS furniture has to be grown in NHS-owned forests).

The private sector is also, and has always been, heavily involved in the delivery of healthcare. In most routine cases, ‘healthcare’ simply means seeing a doctor, getting a prescription, and taking the medicine. If the term ‘private healthcare’ makes you shudder, open your medicine cabinet and read the labels on the packets. You won’t see the NHS logo on any of them, but the names of various private pharmaceutical companies, owned by shareholders and run for profit. And presumably, the GP who wrote that prescription was not an NHS employee either, but a self-employed contractor.

It does not stop there. Look around you in any NHS hospital or diagnostic centre: not a single piece of the medical equipment you will see there has been produced by an NHS-owned entity. They have been produced by private companies, and for a profit. Even some of the doctors will have studied at private medical colleges, and others may have received some of their training at private medical facilities. If you’re still with me, resist the urge to jump up and down and shout ‘But that’s different!’ It isn’t.

My point is not that just because some aspects of healthcare have always been delivered on a for-profit basis, we might as well sell off everything. None of the above says anything about the relative merits of public or private provision, and there are respectable arguments cautioning against being too optimistic about the private sector’s abilities. All I’m saying is that our perceptions of where for-profit provision is acceptable, and where it is beyond the pale to even consider it, are very much shaped by what we are accustomed to. Suppose that in 1948, pharmaceutical companies and producers of medical technology had been nationalised, and suppose that since then, NHS patients had never come across a privately manufactured drug or medical device. Further, suppose that today, a senior health politician had suggested that in the future, the NHS might buy some drugs and some pieces of medical technology from a private supplier, perhaps a big US corporation. And now, try to imagine for a second what the newspaper headlines would look like tomorrow.

But the habituation process can also work in the opposite direction, and this is why I believe that in the long run, NHS purism has no future. A lot of the comments I have received since the publication of the paper (Did I mention my NHS paper? Which you can read here?) have been of the unquotable variety, but a few have been along the lines of: ‘I have always been a defender of the NHS and its founding principles, however, I have recently had a scan/test/whatever at a private centre, and I have been very satisfied. Maybe we are being a bit too hysterical.’

This is the Sushi effect in action. It will eventually lead to a normalisation of private provision, and this will change the terms of the debate. Those of us who argue for a more pluralistic, polycentric healthcare system will then find it a lot easier to get our arguments across. Since we’ve got the better arguments on our side, that will be all we need.