I go to class

Today we had a class on MFR (médecine fondé sur les résultats--translates to Evidence-based medicine). A lot of people consider this class to be a ton of BS (myself included, sometimes) but really EBM is uber-important and can be quite interesting.
You might be surprised, but a lot (waaaay too much, in fact) of medicine is based on anecdotal evidence and tradition. I mean, when my parents were kids, Docs were prescribing cigarettes to pregnant women to help alleiviate stress! A couple hundred years before that, bloodletting was common practice (this comes from ancient "wisdom"--Greek, I think--that the body is composed of four "humours," blood being the one that most often overpowers the others volume-wise, and thus had to be let out of the body to restore humoural balance). So really, medicine is a very young practice, at least if you're considering the way we do it today.
And some funny stuff comes up when you look at the facts! Today we read a paper that more or less showed that eradication of H.pyloi, a bacteria that lives in many peoples stomachs, doesn't actually help fucntional dyspepsia (stomach aches after eating that aren't associated with ulcers). You can totally eradicate the bacteria, but there's no significant change in symptoms (what the patient feels) compared to those taking a placebo. COOL! Pretty much everyone thought that H.pylori was responsible for the symptoms...but apparently that's not true. So what causes the discomfort? Who knows...
All this is a good illustration of the fact that a lot of assumptions, or common sense, aren't actually true. You can't take anything for granted, ESPECIALLY in medicine. That's why we've got EBM. It sure takes a while, but it's the only way to turn medicine into a truly useful enterprise, and ensure that we never start practicing useless or even dangerous practices like bloodletting. (Homeopaths, I'm directing a skeptical eye your way...)