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What is the difference between:

  1. "I promise not to misbehave."
  2. "I promise to not misbehave."

as in something a kid would say to convince its parents that it will behave well?

marked as duplicate by Eddie Kal, Jason Bassford, Hellion, choster, Jeff Zeitlin Dec 18 '18 at 18:16

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Some people think it's important to avoid "splitting infinitives." In these sentences, "to misbehave" is an infinitive verb and "splitting" it means inserting a word between the "to" and the "misbehave." In your example 2, "promise to not misbehave" is a split infinitive.

I happen to think this is an entirely pointless rule. Sometimes it makes more sense, either because of clarity, or as Andrew says, because of the sound of the sentence to split the infinitive.

One commonly cited example of a split infinitive that sounds much better split is that Star Trek slogan, "to boldly go where no one has gone before." This breaks the split infinitive rule - which would tell you that it must be "to go boldly" or "boldly to go" - but sounds much nicer.

Additionally, in some circumstances repositioning the "not" can subtly change the meaning of the statement:

Be aware that putting "not" or another adverb between "to" and its verb adds some emphasis to that adverb. For example, in the sentence "They decided not to stay another night" the phrase "they decided" is the most important information, but the sentence "They decided to not stay another night" tells us that maybe they decided to stay another night before, but now it is important that they will not stay.


The meaning is the same - there is no difference. A child would probably say either one, but it seems promise not to is more grammatically correct, as described here.

  • 1
    Please summarize what the website says, in terms of why promise not to is "more grammatically correct." In a few years, the link may be broken; therefore, you could repeat the gist of why this is the case. – J.R. Dec 13 '18 at 21:32

There is no difference in meaning, but there is a difference in the way the sentence is spoken. The meter of the sentence changes with the word order, as it's common to put a slight accent on "not".

To explain this, let's exaggerate as if the words were set to poetry. Imagine it's like a drumbeat:

I pro' mise not' to mis' be have' (da DAH da DAH da DAH da DAH)

I pro mise to not' mis' be have' (da dah da da DAH (pause) da DAH da DAH)

Of course people don't normally emphasize the meter in this way, but nevertheless there's still an underlying rhythm to every sentence. You can hear this even in ordinary conversation -- pick a scene from a movie and then try to listen to the rhythm of the words, rather than the meaning

For example, this classic scene from Taxi Driver (1976):


You talkin' to me? You talkin' to me? You talkin' to me? [turns around to look behind him] Well, then who the hell else are you talking ... You talking to me? Well, I'm the only one here.

Anyway, because there is this difference in this rhythm, someone may choose to say "not to" or "to not" to fit a particular intonation that (they think) sounds better in that context.

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