What is the difference between "to not" and "not to" and can they be used interchangeably? — Karzan, Iraq
The word "to" is part of the infinitive form of a verb, as in "to run," "to play," and "to write." Some people—grammarians and English teachers, for example—say that "to" must always be next to the verb it goes with, and words like "not" should not split it from the verb. When this happens, as in "tonotrun," it is called a split infinitive. However, in speech, informal writing, and even in formal writing, infinitive forms of verbs are often split, and they are split by more adverbs than just "not." Below are some examples with "to" next to its verb, and some examples of split infinitives.
The infinitives below are not split:
He told us notto split infinitives.
Kelly hoped notto need new shoes before the fall.
They decided notto stay at the hotel.
He wanted neverto go into that house again.
She was able to waitpatiently outside for the store to open.
Below are some split infinitives:
They decided tonotstay another night.
It can be difficult tonotgo back for a second piece of cake.
Jack hoped tonotneed another surgery.
He wanted toneverhave to see them again.
He wasn't able topatientlysit in the busy traffic without complaining.
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.
Sometimes a split infinitive helps to make the meaning of a sentence clear. For example, in the sentence "I asked her quietly to leave" or "I asked her to leave quietly" it is unclear if the asking was done quietly or if the leaving should be done quietly. By saying "I asked her to quietly leave" it is clear that the leaving should be done quietly.
Even though English teachers will say you should not split an infinitive, native English speakers have been doing it for hundreds of years. Generally, a split infinitive is fine to use if it makes a sentence more clear.