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  • Absence of evidence is not evidence of absence.

    Quoted in Project Cyclops: A Design Study of a System for Detecting Extraterrestrial Intelligent Life, rev. ed., ed. B. M. Oliver and J. Billingham (1973). An earlier version by A. R. Burn appeared in a book review by Burn in The Classical Review, June 1969: "absence of evidence is not identical with evidence of absence."