An old man relaxes in a rocking chair on the porch of a frontier homestead overlooking a green valley at sunset.

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Time Enough for Love · 1973

Robert Heinlein

Never underestimate the power of human stupidity.

Behind the line

What it means

Our interpretation.

It is the safest bet about any group of people: somebody will blunder, so plan for it. The idea is older in Heinlein, whose 1941 story 'Logic of Empire' has a character blaming villainy for what is simply stupidity, an early form of what became known as Hanlon's razor. The sentence is quoted by engineers, sysadmins and anyone tempted to assume a plot where a mistake explains it.

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In context

Spoilers for Time Enough for LoveShow the scene

The line is a one-sentence aphorism from Robert A. Heinlein's Time Enough for Love (1973), the novel about Lazarus Long, born Woodrow Wilson Smith. Between the stories the book has two Intermission sections of provocative one-liners, later published separately as The Notebooks of Lazarus Long; Wikiquote lists this sentence among Heinlein's aphorisms. The novel made the shortlist for the Nebula, Hugo and Locus awards without winning, and later won the Prometheus Hall of Fame award in 1988.

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