"Known and Unknown" refers to a widely quoted explanation — praised by some as philosophy, criticized by others as double-talk — Rumsfeld offered in 2002 about the lack of evidence that Iraq was supplying terrorists with weapons of mass destruction.
"Reports that say that something hasn't happened are always interesting to me, because, as we know, there are known knowns; there are things we know that we know," he said. "There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know."
Philosophy? Double-talk? How about long-used definitions in Risk, Project, and Program Managment disciplines?
Perhaps the media's cluelessness concerning such concepts is understandable. After all, this way of determining where one has gaps in knowledge and the nature of those gaps is a tool used by people who, y'know, actually do something instead of just talking and writing about it.
Which come to think of it, probably also explains why the Media and the Left tried to hold President Bush accountable for 'mistakes' that were merely outcomes that could not be reliably predicted: they never heard of Thucidides' Imponderables either.