I don't disagree with most of what you have said. We are on the same page about the practicalities for physicians of diagnosing with imperfect knowledge.

And I certainly agree that these symptoms are real and not psychosomatic, just because they might not always have an easy or correct name that we can give them today. I also appreciate the importance of validation, especially in the context of a medical community that all too often dismisses difficult patients. I have been dismissed and I know many other patients have.

But, if in your last paragraph you are suggesting, that we should define "chronic fatigue syndrome" as broadly as persistent, debilitating fatigue, as has been done in the Oxford definition and to a lesser extent in the definitions advanced at different points by the CDC, I totally disagree. The information on "chronic fatigue syndrome" may seem imperfect to you, and it is to a degree, but the suggestion that we should define the disease broadly by fatigue has historically been driven (and is still driven) by people who believe that the symptoms of the disease are perpetuated by "false illness beliefs" and maladaptive coping. They defined the disease by persistent, debilitating fatigue and created flawed studies on that heterogeneous patient population that "proved" their point.

Meanwhile, there has long been consensus among people who seriously consider the biomedical evidence that post-exertional malaise -- a severe worsening of symptoms following activity that can last for days and, for the sickest patients, weeks -- is the defining trait and that the disease evinces a unique pattern of symptoms that can be identified. For decades, long before the creation of the CDC Fukuda definition (and the definitions that preceded it and followed it), experts have focused on this disease and created definitions to identify it. While it may seem like little is known about "chronic fatigue syndrome," the reality is a great deal is known, and has been known, though biomedical researchers struggle to get funding for biomedical research, which makes replication difficult, and researchers who do focus on the disease are routinely belittled and ostracized by colleagues, which creates a small pool of researchers. There is no debate about whether to define the disease as broadly, as persistent, debilitating fatigue, or strictly, as has been done in the CCC and ME-ICC case definitions, created by disease experts. The debate is artificial and manufactured by people who dismiss any biomedical evidence out-of-hand.

The people who actually seriously consider the biomedical evidence believe the disease is real, is not perpetuated by "false illness beliefs," and is a disease that is biomedical in origin with the defining trait of post-exertional malaise. For example, Vanderbilt professor Ellen Clayton, who recently chaired the IOM panel that examined the disease and had no prior experience with it, came away from her investigation "completely convinced," saying that "the scientific evidence, the evidence from the patients, the advocates, the clinicians was really clear." You might claim that this reflected political expediencies, but the patient community actually lobbied against the IOM and experts signed a joint letter opposing the creation of a new case definition by the panel. World-class researchers who take the time to understand the disease come away convinced. After a 2011 study of the drug Rituxan for CFS patients, Jonathan Edwards, pioneer of B-cell depletion therapy in Rheumatoid Arthritis, became convinced in the reality of the disease defined by post-exertional malaise. He has agreed to act as scientific advisor to a British Rituxan replication study and spends time discussing the disease on a patient forum. Ian Lipkin, a world-renowned virologist, after entering the disease through a government effort to prove or disprove XMRV, now spends his time in this disease. He participated in this study and plans to study the microbiome if he can get funding. The government won't fund his research and patients have only managed to raise 200k so far.

As to the people left behind by defining the disease strictly, as experts have long said it should be defined, they may lose a diagnosis that can give them comfort, but removing actual "CFS" patients from their ranks makes it more likely that we will figure out what causes their suffering. This is an improvement. And lumping them in a persistent, debilitating fatigue diagnosis for the foreseeable future may comfort them today, but will leave them to the dogs for the rest of their life. There is a long history that you need to understand in order to appreciate where consensus lies in this disease.