Murphy's law
expressionops culture
'Anything that can go wrong will go wrong' - engineering's oldest planning assumption.
The name traces to Captain Edward Murphy and the 1949 rocket-sled tests at Edwards Air Force Base, though participants told conflicting versions of who said what, and the sentiment predates them all. In operations it is not pessimism but method: design for the failure mode, because given enough deployments it will occur. Every redundancy, backup, and chaos drill is Murphy's law taken seriously.
Anything that can go wrong will go wrong. The attribution is to Edward Murphy, an engineer on rocket sled tests in 1949, and the original context matters: it was not fatalism, it was a design principle. If a component can be installed backwards, someone will install it backwards, so design it so it cannot be.
That reading is the useful one and the one usually lost. Murphy's law is an argument for defensive engineering, not a shrug. It is why connectors are keyed, why dangerous commands ask for confirmation, and why a good API makes the correct usage the easy one. The pessimism is instrumental: assume the failure mode will happen and remove the possibility rather than the intention.
In operations it maps directly to blast radius thinking. The certificate will expire on a holiday, the disk will fill during the incident, the runbook will be on the system that is down. Each of those is a specific thing that can go wrong, and each has a preventable version, which is why writing them down before they happen is the whole discipline. Fatalism does nothing; enumeration does a great deal.