Assumption is the mother of all foul-ups.

The earliest located instance in the provided material is a 1972 newspaper profile of a U.S. presidential campaign advance staffer, Stephen Robbins, who used the line as practical advice to colleagues while planning travel and events. Later appearances show the saying circulating in other high-stakes domains (e.g., skydiving, aviation, military/journalism commentary), suggesting it spread as a general caution against acting on unverified beliefs.

The adage warns that treating guesses as facts is a common root cause of preventable errors; checking details and confirming information reduces the chance of avoidable failures.

Don’t assume: assumption is the mother of foul-ups.

Assumption is the mother of all screw-ups.

Assumption is the mother of all mistakes.