Most doctors, especially the good ones, are acutely aware of the limits of their knowledge. I have learned from those much more experienced and qualified than me that humility is something to be cultivated over time, not lost.

Our field is built around trying to prove ourselves wrong. In hospitals we hold morbidity and mortality meetings trying to show where we have failed, what we need to change, how we can do better. Our hospital work is audited to identify where we fell short of our ideals. Through scientific research we try to disprove the effectiveness of treatments. Our failings are exposed from the inside.

The nature of evidence-based health care is that practices change as new evidence emerges.

That is also the case for other health professionals whose practice is based on science, like qualified dietitians, physiotherapists, occupational therapists and psychologists. Guidelines are revised, advice is reversed — on blood pressure, diet, hormone replacement, opioid prescribing. This can be immensely frustrating for patients, even though it is what we must do to provide the best possible treatment.

In the face of such doubt, it is not surprising that some individuals, even those who are intelligent and well educated, are swept away by the breezy confidence of health gurus, who are full of passionate intensity while the qualified lack all conviction, to borrow from Yeats.

It is a cognitive bias known in psychology as the Dunning-Kruger Effect. In short, the less you know, the less able you are to recognize how little you know, so the less likely you are to recognize your errors and shortcomings. For the highly skilled, like trained scientists, the opposite is true: The more you know, the more likely you are to see how little you know. This is truly a cognitive bias for our time.