IM - Original

Internal and Emergency Medicine

, Volume 3, Issue 1, pp 25-31

First online:

Rational error in internal medicine

  • Giovanni FederspilAffiliated withDepartment of Medical and Surgical Sciences, Clinica Medica 3, University of Padua Email author 
  • , Roberto VettorAffiliated withDepartment of Medical and Surgical Sciences, Clinica Medica 3, University of Padua

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Epistemologists have selected two basic categories: that of errors committed in scientific research, when a researcher devises or accepts an unfounded hypothesis, and that of mistakes committed in the application of scientific knowledge whereby doctors rely on knowledge held to be true at the time in order to understand an individual patient’s signs and symptoms. The paper will deal exclusively with the latter, that is to say the mistakes which physicians make while carrying out their day-to-day medical duties. The paper will deal with the mistakes committed in medicine trying also to offer a classification. It will take into account also examples of mistakes in Bayesian reasoning and mistakes of reasoning committed by clinicians regard inductive reasoning. Moreover, many other mistakes are due to fallacies of deductive logic, logic which they use on a day-to-day basis while examining patients in order to envisage the consequences of the various diagnostic or physiopathologic hypotheses. The existence of a different type of mistakes that are part of the psychology of thought will be also pointed out. We conclude that internists often make mistakes because, unknowingly, they fail to reason correctly. These mistakes can occur in two ways: either because he does not observe the laws of formal logic, or because his practical rationality does not match theoretical rationality and so his reasoning becomes influenced by the circumstances in which he finds himself.


Mistake Bayesian reasoning Inductive reasoning Deductive logic Psychology of thought