From George Bernard Shaw’s Preface to The Doctor’s Dilemma

The test to which all methods of treatment are finally brought is whether they are lucrative to doctors or not.

Nobody supposes that doctors are less virtuous than judges; but a judge whose salary and reputation depended on whether the verdict was for plaintiff or defendant, prosecutor or prisoner, would be as little trusted as a general in the pay of the enemy. To offer me a doctor as my judge, and then weight his decision with a bribe of a large sum of money and a virtual guarantee that if he makes a mistake it can never be proved against him, is to go wildly beyond the ascertained strain with human nature can bear.

The large range of operations which consist of amputating limbs and extirpating organs admits of no direct verification of their necessity. There is a fashion in operations as there is in sleeves and skirts. … There are men and women whom the operating table seems to fascinate: half-alive people who through vanity, or hypochondria, or a craving to be the constant objects of anxious attention or what not, lose such feeble sense as they ever had of the value of their own organs and limbs.

But just as the best carpenter or mason will resist the introduction of a machine that is likely to throw him out of work, … so the doctor will resist with all his powers of persecution every advance of science that threatens his income… . It unluckily happens that the organization of private practitioners which we call the medical profession is coming more and more to represent, not science, but desperate and embittered anti-science: a state of things which is likely to get worse until the average doctor either depends upon or hopes for an appointment in the public health service for his livelihood.

The recklessness with which they now recommend wintering in Egypt or at Davos to people who cannot afford to go to Cornwall … often makes one wonder whether it is possible for a man to go through a medical training and retain a spark of common sense.

The only evidence that can decide a case of malpractice is expert evidence: that is, the evidence of other doctors; and every doctor will allow a colleague to decimate a whole countryside sooner that violate the bond of professional etiquet by giving him away.

… The effect of this state of things is to make the medical profession a conspiracy to hide its own shortcomings. No doubt the same may be said of all professions. They are all conspiracies against the laity.

And the healthier the world becomes, the more they are compelled to live by imposture and the less by that really helpful activity of which all doctors get enough to preserve them from utter corruption. For even the most hardened humbug who ever prescribed ether tonics to ladies whose need for tonics is of precisely the same character as the need of poorer women for a glass of gin, has to help a mother through child-bearing often enough to feel that he is not living wholly in vain.

It does happen exceptionally that a practicing doctor makes a contribution to science; but it happens much oftener that he draws disastrous conclusions from his clinical experience because he has no conception of scientific method, and believes, like any rustic, that the handling of evidence and statistics needs no expertness. The distinction between a quack doctor and a qualified one is mainly that only the qualified one is authorized to sign death certificates, for which both sorts seem to have about equal occasion.

All that can be said for medical popularity is that until there is a practicable alternative to blind trust in the doctor, the truth about the doctor is so terrible that we dare not face it.