Why We Identify With Zebras

The Web MD definition of Zebra:

The term “zebra” in medicine does not refer to the striped African animal but to an unlikely diagnostic possibility. It comes from an old saying in teaching medical students about how to think logically in regard to the differential diagnosis: “When you hear hoof beats, think of horses, not zebras.”

For example, when someone develops a mild transient cough, tuberculosis is a “Zebra”. For another example, following the discovery of West Nile fever in New York City in September, 1999, the Centers for Disease Control and Prevention warned doctors to expect more infectious disease “zebras” (disease due to rare microbes).

The Origins of the Horses vs. Zebras Principle:

This horses vs. zebras principle is known as Occam’s Razor.

Wikipedia tells us that “Occam’s Razor (also spelled Ockham’s Razor) is a principle attributed to the 14th –century English logician and Franciscan friar, William of Ockham. It forms the basis of methodological reductionism, also called the principle of parsimony or law of economy.

It is simplest form, Occam’s Razor states that one should make no more assumptions than needed. Put into everyday language, means: “The simplest explanation is the best.”