[JohnG45]

They showed that in any mathematical system, there are certain questions that cannot be answered. They're not really difficult — they're unknowable.

And in February, 2002, at a Department of Defense briefing, Donald Rumsfeld agreed:

"There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."

[Delta 21]

..and the last category is exponentially larger than all the others combined.

[stevio]

Makes sense.

[Dustoff45]

There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know

Known Knowns - Educated, I know what I know when I know it.

Known Unknowns - Scholarly research and study, I don't have the answer yet, but still thinking and looking for it.

Unknown Unknown - Village Idiot level of ignorance. (Democrat)

[no-s]

This would be the 2nd category - the known unknowable...

I miss watching Donald Rumsfeld chop off the heads of ignorant reporters.

[zeugma]

And in February, 2002, at a Department of Defense briefing, Donald Rumsfeld agreed:

"There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."

That wasn't original to him. I never understood the crap he took for making the statement. It's absolutely true. It's the unknown unknowns that really bite you in the ass.