Diagnosis, diagnosis, diagnosis

What is it that doctors offer that other professionals cannot? “Diagnosis, diagnosis, diagnosis,” answered a former chief medical officer for England. A nurse might one day transplant a heart, a technician anaesthetise a patient, and a pharmacist control a patient's complex drug regimen. But doctors are needed for diagnosis. The doctors' doctor is not a heroic surgeon cutting into a diseased brain but the doctor, probably a physician, who using almost magical skills can make the diagnosis when all about her are lost in a profusion of radiographs, printouts, and misleading conjecture. And quite right too—because diagnosis is hard.

Diagnosis is also hard to …