I don’t suppose that the people who taught me at medical school thought that they were promoting particular mental models. They were trying (and sadly failing) to make me the best doctor they could. But just like the man who didn’t know he’d been speaking prose all his life, they were promoting mental models. One was always wrong and one is no longer right.

One mental model was that doctors were scientists who used the natural sciences to solve people’s health problems. It still prevails and is still wrong. Some doctors are scientists, but most, as all doctors know, are not. A few months’ exposure to molecular biology and physiology does not make you a scientist. Scientists pose falsifiable hypotheses, design interpretable experiments, gather data, and mostly find that their hypothesis was wrong. That’s not how doctors work, and as a knowledgeable patient I wouldn’t want them to. Doctors work more like dressmakers or carpenters: they learn through apprenticeship and experience and work mostly by using familiar responses to familiar problems.

The mental model that once made sense but has lost its usefulness is “diagnose, treat, and cure.” That’s the model I was taught, and I fear that it lingers on in medical education and worse in the minds of some doctors and many patients.

Around 20 years ago the then chief medical officer, Ken Calman, said that what doctors did uniquely in the health system was “diagnose, diagnose, diagnose.” (There was a fashion at the time for triple repetition.) In contrast, a general practitioner friend responded when I told her of Calman’s maxim: “Nonsense, I go weeks without a diagnosis.” GPs are supposed to make a tripartheid diagnosis (physical, psychological, and social), but this isn’t what my teachers meant by diagnosis and perhaps stretches the concept to the point where it isn’t useful.

Diagnosis is no longer important because most patients have long term conditions. Doctors know their diagnosis, and so do they. Some patients, particularly in the television series House, present with mysterious problems where a brilliant and maverick doctor (played by Hugh Laurie in House) makes an extraordinary diagnosis and saves the patient, but that happens more on television than routine healthcare.

Because of the change in epidemiology from patients with single acute problems to those with multiple, long term conditions, treatment has become the province of patients rather than doctors. If you are a patient with acute meningitis then your recovery will depend mainly on what the doctors and nurses do, but if you have diabetes, hypertension, or chronic obstructive pulmonary disease it depends much more on what you do. Can you change your lifestyle, stop smoking, lose weight, exercise more, and ensure that you take your unremarkable medicines regularly and properly? Your behaviour not the doctor’s will determine how well you do.

Again because healthcare is dominated by long term conditions there is little curing any more. Medicine is about ameliorating, palliating, listening, explaining, advising, and consoling. It’s not glamorous. It should also be about caring, but patients accept that doctors are “too busy” for that (sometimes, I fear, in pursuit of the mirage of diagnosing, treating, and curing). I often used to drive past “The Home For Incurables” in Putney, snigger, and be grateful that I wasn’t in there. But now most of us are incurable, although the Putney hospital now has a euphemistic name.

I hope that I’m wrong that medical educators, some doctors, and many patients have not acknowledged the near death of the “diagnose, treat, cure” model, but I fear I’m right.

Richard Smith was the editor of The BMJ until 2004. He is now chair of the board of trustees of icddr,b [formerly International Centre for Diarrhoeal Disease Research, Bangladesh], and chair of the board of Patients Know Best. He is also a trustee of C3 Collaborating for Health.