A lot of this is front-loaded in the 4 years of undergraduate training, 4 years of medical school, and 4-6 years of residency training that physicians do.<p>Physicians are trained to preload all possible diagnoses based on a certain set of initial symptoms--they have ideas about what the potential answer might be when you inform them of their symptoms, but in order to narrow that space down, additional workup needs to be performed (tests, imaging, etc) and until those results come back, anything else they say is speculation.<p>(edited, fixed a typo)