Murphy’s Law
Etymology
Widely attributed to Edward A. Murphy Jr., an engineer on U.S. Air Force rocket-sled tests around 1949, after a set of sensors was wired incorrectly; the exact wording and who coined it are disputed. The phrase spread through aerospace and engineering culture as a maxim of robust design — assume failure and build against it. It is less fatalism than a prompt to anticipate what can break.
noun phrase · /MUR-feez LAW/
The adage that anything that can go wrong will go wrong.
What it names
A wry handle for defensive pessimism — plan as if the worst-case failure is bound to happen.
Example
True to Murphy’s law, the demo crashed the moment the investors walked in.
Related idea
Murphy’s law says whatever can fail will; Hanlon’s razor says never attribute to malice what is adequately explained by incompetence — one anticipates failure, the other explains it charitably.
See also