Which one is correct?
1. I cannot do not eat for 5 days straight
2. I cannot not eat for 5 days straight
3. I cannot not to eat for 5 days straight

  • (2) is correct. However, you would only use a double negative like that in colloquial speech. In more formal language it would have to be something like "I cannot abstain from food for five days". Commented Jan 22, 2020 at 8:52
  • 1
    This is not a double negative. A double negative is two negatives both used to express only one negation in total. Like "I can't get no satisfaction" to actually mean "I can't get satisfaction". Here you have two negatives that are used to express two different negations. The sentence does not mean "I cannot eat". The sentence does actually mean "I cannot not eat".
    – ЯegDwight
    Commented Jan 22, 2020 at 10:05
  • 1
    @ЯegDwight Not necessarily. What you describe is a phenomenon in English with a long history of debated valence, but "double negative" as a concept is more than just that. As per Wikipedia: "A double negative is a construction occurring when two forms of grammatical negation are used in the same sentence... In some languages, double negatives cancel one another and produce an affirmative; in other languages, doubled negatives intensify the negation. "
    – Eddie Kal
    Commented Oct 28, 2020 at 17:49

2 Answers 2


While it is possible to say "I cannot not eat..." You should avoid this construction if possible. In this case you could say "I cannot fast for 5 days" or "I cannot go without food for five days".

Other words don't have convenient ways of expressing the negative "not eat" with positive verb "fast". However it is usually possible to say "I cannot stop breathing for five minutes", or perhaps "I cannot give up jogging for five months."

There is no expression "I cannot not X" that can't be better expressed in a way that avoids "cannot not".

  • Once you've seen it, you can't not see it!
    – Colin Fine
    Commented Jan 23, 2020 at 0:07

None of them.

2 is most close to the answer but we say:

I cannot eat for 5 days straight

cannot already contains a not, no need to write cannot not.

  • But OP is asking about a construction with multiple negations. The inclusion of the extra "not" is intentional.
    – Eddie Kal
    Commented Oct 28, 2020 at 17:43
  • apparently then, none makes sense for me. i have never heard nor read, double negation in english
    – Cuenc
    Commented Oct 28, 2020 at 18:08
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    Really? "I'm afraid we've run out of food. We'll be getting some in next week." "But I can't not eat for five days straight!"
    – Colin Fine
    Commented Oct 28, 2020 at 18:59

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