From David Marjot
In your special issue on thought, you list Occam’s razor as a tool for easier thinking, as follows: “Don’t invent a complicated explanation for something if a simpler one will do” (21 September, p 38). It is also useful in medicine: do not make two or more diagnoses when one will explain the symptoms.
But, in or out of medicine, the razor may sometimes fail. We should recall Hickam’s dictum: “A patient can have as many diseases as they damn well please.” This is the same as saying it is often more likely that a patient has several common diseases than a single, rarer one that explains their multiple symptoms.
Weybridge, Surrey, UK
