Murphy's law^[a] is an adage or epigram that is typically stated as: "Anything that can go wrong will go wrong."

Though similar statements and concepts have been made over the course of history, the law itself was coined by, and named after, American aerospace engineer Edward A. Murphy Jr.; its exact origins are debated, but it is generally agreed it originated from Murphy and his team following a mishap during rocket sled tests some time between 1948 and 1949, and was finalized and first popularized by testing project head John Stapp during a later press conference. Murphy's original quote was the precautionary design advice that "If there are two or more ways to do something and one of those results in a catastrophe, then someone will do it that way."^[1][2]

The law entered wider public knowledge in the late 1970s with the publication of Arthur Bloch's 1977 book Murphy's Law, and Other Reasons Why Things Go WRONG, which included other variations and corollaries of the law. Since then, Murphy's law has remained a popular adage, though its accuracy has been disputed by academics.

Similar "laws" include Sod's law, Finagle's law, and Yhprum's law, among others.

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).