Doctors actually do use a very similar mechanism - differential diagnosis, as popularized on House (well, probably not exactly as popularized, but someone who's actually a doctor can go over the differences). The idea is to list all the possible diseases that could cause a patient's symptoms, and then run the appropriate tests or treatments to cut the search space by as much as possible. Cutting in half is often not possible in medicine, and they also account for how dangerous & urgent the condition may be when prioritizing.