Yes, I would not or No, I will?

Have you ever heard of a double negation? Have you ever seen it at 8.30am before finishing your first cup of coffee? One weekday morning, I was rushing through preschool drop off while trying to read the following note:

I shook my head and tried to open my eyes as wide as I could in an attempt to bring myself to full consciousness. Does a mark in the Yes column mean that my daughter will not be attending the school on the listed dates? Or will it mean that, yes, she will be coming in? It is me or it's very confusing? Perhaps we should try the No column: No, she will not be attending. OMG! I felt completely at loss.

Wait, this is double-negation. The rule of double-negation is that for any proposition P, not-not-P is P. Like not-not-True is True. So, replying “No” to the sentence “My child will not be attending The Center on the following dates” should mean – “She will be in!” I smiled the next day when I saw another group of parents crowded around this note, all puzzled. Eventually it was re-written, as even the author was unsure how to interpret the results. So, forget double negation, let's just talk straight!

If no-no-something will mean "yes", how about yes-yes-something? Can it mean "no"? In general it does not work. Yes-yes-something does not mean not-something. However, there is a great story about a linguistics professor that was giving a lecture and explaining double negation rules and examples. He concluded by saying that there is no case where a double positive forms a negative. To which a student responded: "Yeah, right." That sounds like "No!"

More math adventures in parenting: Mommy, I am afraid to die...


  1. Here is another great example of a logical confusion. Songwriter and performer Les Julian asked kids at the concert, telling them to raise their hands if they agree:
    How many of you like to sing?
    How many of you like to sing but are so shy that sing only when you are alone in the shower?
    How many of you are so shy about the singing that you would not even raise your hand right now?

    How can you answer "yes" to the last question?
    And how would you answer "no"...

  2. Two examples of sentences that are not technically double negations, however you will find yourself applying double negation rules in your mind to comprehend them:

    "Never trust anyone who goes around telling lies."

    From my daughter: "Daddy. I know how to get anything from you. I ask once, and you say "No." I ask twice and you agree."


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