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NullVoid » Rumsfeld NullVoid » Blog Archive » Rumsfeld



I went to Washington DC early this week to participate an NBER conference on Innovation Policy and Economy, there are a lot of government officials participating.  A professor from Northwestern (DANIEL DIERMEIER, he is a great presenter, I liked his slides so much) quoted Rumsfeld’s famous sentence on "known knowns and unknown unknowns".

"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 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." 

That was funny, and is quite true. 

His comment on Iraq’s Mass destruction weapons is also hilarious:


"the absence of evidence is not the evidence of absence"


To me, these are very good guidance to research!  In econometrics, known knowns are probably those observables, known unknowns are usually captured by the error term.  The big headache is unknown unknowns which can give us headache of missing variable issues.

The second quote tells us that insignificance of a regression does not mean there is no relationship between the dependent and independent variables.

Oh, here is another one:

"I don’t know what the facts are but somebody’s certainly going to sit down with him and find out what he knows that they may not know, and make sure he knows what they know that he may not know."

Anyone who took a course in game theory should ring a bell here on the definition of common knowledge: I know you know, and you know that I know you know, I know that you know I know you know, … …


Simply hilarious 

5 Responses to “Rumsfeld”

  1. maggie Says:

    ‘known knowns and unknown unknowns’: This is an interesting one. It reminds me of something that I came across the other day:

    There are three types of people in the world.

    Those who know (a very rare breed).
    Those who know they don’t know.
    Those who don’t know they don’t know.

    At the very least, you will be moving up to category 2.

  2. maggie Says:

    ———- says Dr. T. Vilis to his students.

  3. ET Says:

    This is a good one. :-)

    What about those who don’t know they know? These should be rarer than the first type. An example I can give is about my daughter.

    Her favorate TV channels are 23 and 31 (both PBS kids and WGBH), when she turns on the TV, she would ask shall I push “up” or push “down”. I usually tell her:”it depends on where you are”. But if she remembers that last time she reached 31 by pushing “up”, she would just be pushing “up”. Of course she has been right all the time since as long as you push “up”, you will reach the channel you want.

    I know she can count up and count down, so she should know how to reach the desired channel most efficiently. In this case, she DOES NOT KNOW SHE KNOWS. Then I figured out a way to teach her: “we are living on the 27th floor, if you want to go to 23rd floor to visit your friends, should you press up or down?” She has no problem to answer this question. Then the next time when she needs to find channel 23, I would ask her:”think about the elevator example, now we are in 31st floor, should you press up or down to go to 23rd floor?”

    She answers:”for elevator I press down, but for TV, I press up, ’cause I can find 23 by pressing ‘up’ each time”.

    She has a point.

  4. maggie Says:

    well, this is a cute example of empiricism outplaying logic. ;>

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