Occam's Razor vs. Hickam's dictum

In medicine, we like to live by a rule first articulated by William of Ockham, a 14th-century Franciscan friar, that the simplest explanation is often the best. In medicine that usually means that most of the time, a symptom can be explained by a single diagnosis. Not so in this case. Indeed, it was in talking about this case that I came across what is known as Hickam's dictum, a saying attributed to Dr. John Hickam, a 20th-century physician and teacher: "Patients can have as many diseases as they damn well please."

 

Think Like a Doctor: A Peculiar Heartbeat Solved! - NYTimes.com

 

* * *

I went through it for years, with one doctor diagnosing sinus headaches, the next saying the previous one was a quack and diagnosing migraines, the next saying the previous one was an idiot and re-diagnosing sinus ... until I finally got to a doctor who suggested "maybe you have both?" and admitting that SHE thought of it because she herself has both.

 

Sometimes, "this is not a symptom of Disease X" means you've been misdiagnosed.  And sometimes it means that in addition to Disease X, you also have Diseases Y and Z.  The good doctors will consider both possibilities.