The first time anyone told me that something was unknowable was in science class when I learned about the Heisenberg Uncertainty Principle. You cannot know the exact momentum and position of an electron at the same time.
Well, surely, with better tools and more precise ways of measuring... "No, no, no, you don't get it!" My p-chem professor had crazy, uncombed hair and he had missed a button on his shirt. All the buttons were off, so it was hard to take his words seriously. "A thousand years in the future, with the best tools available, we will never know."
Medicine is not without its own uncertainty. And that doesn't sound so bad in an academic sense, but it's not very comforting to patients. How do you tell a patient that you don't know? I don't know what's causing your abdominal pain. I don't know if it's from your heart or if it's acid reflux. I don't know.
As a practicing physician, I've gotten used to it. The students seem to have a much harder time with it. As a resident, I worked with a group of students, and uncertainty was a problem...
"So, is it Buerger's Disease?"
"The case from this week, Buerger's Disease, right?"
"Oh, the case. There's no answer. It's just an exercise."
"But we were supposed to think about Buerger's Disease."
"It's in the differential, but there are lots of possibilities."
"But it's really Buerger's."
"Well, there's no answer."
"How can there be no answer? It's Buerger's Disease!"
In medicine, there are lots of questions where we never get any answers: poorly differentiated tumors, diseases without any diagnostic tests, all sorts of situations without clarity. Sometimes we spend time and energy to try to find the answer. Sometimes we don't even bother. But the truth is that in medicine, there is uncertainty on all sides.