Unknown Unknowns
I was surprised today that some students I was talking to couldn’t identify the leading American philosopher and social scientist responsible for this pithy summation of the limits of human knowledge:
Obviously it’s from before their time. How about you? Without using Google, can you identify the origin of this clear and insightful description?
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In the Dark 
May 2, 2023 at 9:09 pm
Donald Somebody
May 2, 2023 at 9:11 pm
Reinsfelt ?
May 2, 2023 at 10:01 pm
The immortal words of Donald Rumsfeld.
And now I’m cheating, but uttered on February 12, 2002. But I do teach a course, the evolution of the human diet, using the book by the same name, where the subtitle sounds: The Known, the Unknown, and the Unknowable.
May 2, 2023 at 11:04 pm
If you think about it, it’s not as stupid as it sounds at first! Similar to that ancient Greek saying about unconscious incompetence and so on.
May 3, 2023 at 1:11 am
In the Bayesian language, this is like having a prior on prior.
May 3, 2023 at 3:08 am
People mocked Rumsfeld for this, which I always thought was unfair. It’s quite possibly the most intelligent thing he ever said.
May 3, 2023 at 7:09 am
Indeed it is, but that bar is rather low..
May 3, 2023 at 8:55 am
I always thought this was a brilliant quote. The only trouble is it’s incomplete: the remaining option is “unknown knowns” – things that we know but don’t realise that we know. I see this in action every time I ask a class of students if they know some piece of calculus: the normal response is blank stares, even though I am certain that the topic concerned was covered in courses that they all passed the previous year.
May 3, 2023 at 9:07 am
Perhaps there is another category: “known at some point but since forgotten”
May 3, 2023 at 9:45 am
Smart of you to add that category, but there are better eaxmples and a whole book about the subject by Michael Polanyi. The category is called ‘tacit knowledge’ and it is the difference between a concert pianist and someone who has memorised by heart a hundred books on piano technique but never actually played one.
May 3, 2023 at 1:14 pm
“Remember, Monsieur Fraser, our weapon is our knowledge, but it may be a knowledge we do not know we possess.” – Hercule Poirot, in The ABC Murders.
May 3, 2023 at 9:10 am
Donald H Rumsfeld, the former U.S. Secretary of Defense, on Feb 12, 2002,
when responding to a journalist’s question at a U.S. Department of Defense news briefing.
May 3, 2023 at 1:44 pm
Donald Rumsfeld. I thought at the time it was nonsense but as time goes by it has made more and more sense, it was just the person saying it I had a problem with.
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