“
Uncertainty is the central, critical fact about medical reasoning. Patients cannot describe exact-
ly what has happened to them or how they feel, doctors and nurses cannot tell exactly what they
observe, laboratories report results only with some degree of error, physiologists do not under-
stand precisely how the human body works, medical researchers cannot precisely characterize
how diseases alter the normal functioning of the body, pharmacologists do not fully understand
the mechanisms accounting for the effectiveness of drugs, and no one can precisely determine
one’s prognosis.
— Peter Szolovits, “Uncertainty and Decision in Medical Informatics,” Methods of Information in Medicine, 34: 111-21, 1995