Q. My daughter spoke to you after one of your lectures and asked if the Space Agency ever hired brain function specialists and she might like that type of job. According to her you said, “I don’t know.” Did you really say that and isn’t that type of response undermining your credibility?

A. She was correct. I did say, “I don’t know.” Did she also tell you that I thought her idea was not only extremely interesting but relevant and suggested she could write to NASA and ask them that question. As to whether saying “I don’t know” undermines my credibility, I have a different opinion. It is honest, saves time and energy for everyone, and acknowledges that no brain knows everything. I know my brain does not know everything and to pretend otherwise strikes me as being pretentious in the extreme.

In my brain’s opinion what would undermine any speaker’s credibility is to “guess” (unless you clearly say it is a guess), or to waffle around trying to drum up an answer, or to state something as if you really know only to have the person discover later that your response was miles off the mark.

Speaking of the phrase “I don’t know” (or its equivalent), I recently read that it is one of the four most important phrases that a person can have in his or her repertoire to be used as appropriate:

• I don’t know
• Please help me
• I was wrong
• Please forgive me