Authors:
  • There are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know.

    Donald Rumsfeld during Department of Defense News Briefing, archive.defense.gov. February 12, 2002.

Topics

Cite this Page: Citation