I share the authors’1 interest in clarifying the popular saying “the exception confirms the rule”; however, the proof of its falsity is not the proof put forward, nor does the warning originate in the eccentric winner of the Nobel prize in Physics, Richard Feynman. The problem is much older, bears no relationship whatsoever to physics, but stems from a poor knowledge of Latin in our field. Marcus Tullius Cicero (106–43 B.C.), in one of his marvelous speeches delivered during the defense of Lucius Cornellius Balbus, stated: “exceptio probat regulam in casibus non exceptis”, the literal translation of which would be “the exception proves the rule in cases not excepted”. The Latin verb “probare” means to prove, and from thence comes “to confirm”. But probare not only means “to prove” or “to confirm”; it also means “to verify”, “to test”. That is, the real translation of the phrase would be “the exception tests the rule”. Or, in other words, the exception is the verification that there is a rule. Never, therefore, that the rule is false.
I will leave the issue of whether medicine is a descriptive or probabilistic science, or both, to others who venture to criticize the editorial and put the physicists in their place. In the case of the exception and the rule, we humbly render unto to Caesar what is Caesar's, and to Cicero what is his.
Please cite this article as: Casan Clarà P. La excepción prueba la regla. Arch Bronconeumol. 2015;51:532.
