Occam's Razor and Hickam's Dictum
Always remember that Occam’s razor is primarily about the aesthetics of scientific theories and only secondarily about actually describing the complexities of reality.
Sometimes five very common events occurring all at the same time are a more likely explanation than one extremely rare event, no matter how elegant that latter explanation may be.
Or to put it another way: when you hear hoofbeats, five horses is still more likely than one zebra.
Hickam’s Dictum is a counterargument to the use of Occam’s razor in the medical profession. The principle is commonly stated: “Patients can have as many diseases as they damn well please”. The principle is attributed to John Hickam, MD. Hickam was a faculty member at Duke University in the 1950s, and was later chairman of medicine at Indiana University.
Hickam’s dictum • Wikipedia