Want to surprise someone?  Admit you don't know the answer to a question, especially if it's a question about a topic on which you're supposed to be an expert.  Personally I respect anyone who has the guts to admit they don't know everything, and I took to heart a lesson I was taught early in my career; if you don't know the answer to a question the right response is "I don't know, but I'll be happy to find out for you."

The guys at Freakonomics recently posted two interesting items related to "I Don't Know."  The first was a response to the question “Why do people feel compelled to answer questions that they do not know the answer to?”.  The answer:

What I’ve found in business is that almost no one will ever admit to not knowing the answer to a question. So even if they absolutely have no idea what the answer is, if it’s within their realm of expertise, faking is just an important part. I really have come to believe teaching MBAs that one of the most  important things you learn as an MBA is how to pretend you know the answer to any question even though you have absolutely no idea what you’re talking about. And I’ve found it’s really one of the most destructive factors in business — is that everyone masquerades like they know the answer and no one will ever admit they don’t know the answer, and it makes it almost impossible to learn.

The second was a comment left by one of their readers:

In my classroom, students lose 1/4 point for wrong answers on quizzes. But for writing “I don’t know,” they get 1/4 point. (A correct answer is 1 point). The rationale is that if someone is in a medical emergency, and someone asks me what should be done, the answer “I don’t know” is much preferable to a guess. “I don’t know” leads the questioner to ask someone who hopefully is knowledgeable.

Part of why “I don’t know is so hard to say” stems from an education system based on attempting every single question, whether you know the answer or not.

P.S.: End-of-year student survey showed students strongly supported the +1/4 point IDK and -1/4 point wrong-answer system. 

If you think about it we do a lot of things that teach our kids to fear admitting ignorance, or making a mistake, and that inevitably leads to sending people into society who value being perceived as right more than they do actually being right.  I don't even want to think about the mischief we've brought on ourselves as a result.