Hickam's dictum
Hickam's dictum is a counterargument to the use of Occam's razor
Occam's razor
Occam's razor, also known as Ockham's razor, and sometimes expressed in Latin as lex parsimoniae , is a principle that generally recommends from among competing hypotheses selecting the one that makes the fewest new assumptions.-Overview:The principle is often summarized as "simpler explanations...

 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
Duke University
Duke University is a private research university located in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco industrialist James B...

 in the 1950s, and was later chairman of medicine at Indiana University
Indiana University
Indiana University is a multi-campus public university system in the state of Indiana, United States. Indiana University has a combined student body of more than 100,000 students, including approximately 42,000 students enrolled at the Indiana University Bloomington campus and approximately 37,000...


When discussing Occam's razor in contemporary medicine, doctors and philosophers of medicine speak of diagnostic parsimony. Diagnostic parsimony advocates that when diagnosing a given injury, ailment, illness, or disease a doctor should strive to look for the fewest possible causes that will account for all the symptoms. However, this principle has very important limits in medical practice. The actual process that occurs when diagnosing a patient is a continuous flow of hypothesis and testing of that hypothesis, then modifying the hypothesis, and so on. In the context of this method, the principle of Hickam's dictum asserts that at no stage should a particular diagnosis be excluded solely because it doesn't appear to fit the principle of Occam's razor. The principle of Occam's razor, or parsimony, does not demand that the diagnostician necessarily opt for the simplest explanation, but instead guides the medical practitioner to seek explanations, without unnecessary additional assumptions, which are capable of accounting for all relevant evidence.

A key reason for using Hickam's dictum as a limiting principle to that of Occam's razor is that it is often statistically more likely that a patient has several common diseases rather than having a single, rarer disease that explains his myriad symptoms. Another key reason is that, independent of statistical likelihood, some patients do in fact turn out to have multiple diseases. In such cases, multiple categories of diagnosis may indeed have independent causes rather than a single source, i.e., may be due to separate events or combinations of events to which the patient may have been subjected or exposed. Thus, Hickam's dictum provides physicians with a counterbalancing principle to the unfettered use of Occam's razor in diagnosis.

An example of the utility of Hickam's dictum is Saint's triad
Saint's triad
Saint's triad is a medical term used to describe the concurrence of the following:# Cholelithiasis# Hiatal Hernia# Diverticular Disease-History:...

 of hiatus hernia
Hiatus hernia
A hiatus hernia or hiatal hernia is the protrusion of the upper part of the stomach into the thorax through a tear or weakness in the diaphragm.- Classification :There are two major kinds of hiatus hernia:...

, gallbladder
In vertebrates the gallbladder is a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. In humans the loss of the gallbladder is usually easily tolerated....

 disease, and diverticulosis
Diverticulosis also known as "diverticular disease" is the condition of having diverticula in the colon, which are outpocketings of the colonic mucosa and submucosa through weaknesses of muscle layers in the colon wall. These are more common in the sigmoid colon, which is a common place for...

. C.F.M. Saint was a British surgeon. His triad has no known pathophysiological relationship, nullifying the usefulness of Occam's razor. Hickam's dictum is similar in principle to Walter Chatton
Walter Chatton
Walter Chatton was an English Scholastic theologian and philosopher who regularly sparred philosophically with William of Ockham, well known for Ockham's Razor.Chatton proposed an "anti-razor". From his Lectura I d. 3, q. 1, a...

's anti-razor.
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