Medicine has, for several decades, been fixated on establishing the validity of treatment - in answering the question 'does this work?'.
How do we know whether a medical intervention works?
The correct answer is: in the same way we know anything in life - which is to say by observing what happens, compared with what we expected to happen.
If somebody's finger is cut off; but is then re-attached by a surgeon and works reasonably well - we know to attribute the result to a surgical intervention.
Or if someone suffers an agonizing pain in a particular part of their abdomen, and experience tells us that everyone in the past who got this unique kind of pain had died, but cutting out the appendix stops them from dying - then we assume the operation was life-saving.
If we expect (from experience, from knowledge) that when we get this kind of headache it will last 24 hours, but when we take tablet X it disappears in 1 hour; then we think it is probably the tablet that helped.
This is first order knowledge in medicine, but there are pitfalls. For example a drug may make someone feel better at first, but they become addicted to or dependent on the drug, and cannot stop taking it. This was noticed for morphine and cocaine - healthy people who took these drugs for the psychological effects would feel terrible when they tried to stop taking it, or needed increasing doses to get the same effect.
Problems of dependence and addiction therefore can usually be detected only when healthy people take the drug, or when an illness is expected to be short term but drug treatment seems to prolong the need for drug treatment.
The placebo response is also a complicating factor - where taking a drug benefits the patient, but the benefit is not due to that specific drug but to the patient's expectation of getting better.
The placebo effect is suspected when a drug's action is weak or unreliable, and varies a lot between people - when a drug effect makes a large difference to situation where we were confident of the outcome, and when it does this reliably time after time, and between many patients - then a placebo effect is usually ruled-out.
My point is that the conditions of medical practice and common sense are usually adequate for doctors and patients to sort-out what treatment do, and how effective they are.
Problems arise when the link between treatment and outcome is more remote due to the unpredictability of outcome in many diseases such as diabetes and breast cancer. This makes it hard to know for sure whether treatment has been helpful or not. And this is where medical science comes in, by providing proxy measures of disease such as blood sugar levels, or biopsy samples and x-ray visualization of tumours.
But uncertainties remain, and in situations of unpredictability, knowledge can never be sure. This fact is not affected by studying large numbers of patients in clinical trials and averaging the results - individual uncertainty is the same as ever it was!
During the golden age of medical discovery, in the mid-twentieth century, evaluation of treatments was a combination of common sense and experience aided by specialization; such that a specialist could build experience of rare conditions, and see patterns of outcomes which would not be apparent to the general practitioner.
Yet modern medicine is now dominated by vast empires of medical evaluators doing formal randomized trials - and progress has either ground to a halt or gone into reverse.
Large randomized trials are only one method among many, can be distorted and biased by selection of patients and methods used, and is bedevilled by poor control; yet they are still ‘officially’ regarded as the best evidence.
And clinical trials can only be done by those with large resources: big corporations and government.
This is a problem across all of our society, not just medicine. We are taught that evidence is only good if it relies on formal, large scale, expensive methodology - and such methods are the preserve of large corporations and government.
So we are in a situation where - supposedly - individual people (doctors, patients, citizens) know nothing whatsoever except what they are told by corporations and governments and those they employ.
So advanced is this process that formal, official knowledge is regarded as correct, even when it is unsupported or actually contradicted by common sense and experience. Common sense and experience in medicine now officially count for *nothing at all*. In some government agencies it is not even permitted to look at any kind of clinical evidence except randomized trials (all of which are conducted using funding from government or industry, and being ruled and regulated by them).
Common sense and personal experience have been officially denigrated to the level of being regarded as utterly irrelevant in understanding our society, just as formal evidence was used to attack common sense and experience in medicine.
We have now reached the point in medicine, in society, where direct personal knowledge is officially regarded as having zero significance, and where official knowledge (e.g. formal surveys and statistics) is the only admissible evidence.
The cost of this is that the worse has displaced the better because the validity of formal methods derives from their underpinning in common sense and experience. Formal methods which are not underpinned by common sense and experience, or which contradict them, are worthless. Indeed, they are deadly – since that was the system of official lies deployed to such devastating effect in totalitarian USSR or China.
The deadliness of a system of official lies (contradicted by common sense and personal experience) is not only material - things like famines, shortages, oppression - but it is deadly to the soul. Officially, a person's own judgment of what is happening, what is right and wrong, true or false, beautiful or hideous - their memories of what has happened to them... all this is officially ignored, denied, extinguished. Only officially-sanctioned statistics are really-real...
This process of denying the validity of common sense and personal experience has all-but destroyed medicine, and is destroying society.