When to Use “Not” and an Infinitive (Split infinitive)

Though usually reserved for informal writing, you can use “not” to split an infinitive when you intend to place special emphasis on the verb inside the infinitive. Otherwise, a rewrite might be necessary.

Here’s what you need to know about splitting infinitives.

What is a Split Infinitive?

An infinitive is a verbal phrase (meaning, a verb phrase that acts as something other than a verb) containing a simple verb preceded by the word “to.” They’re used as nouns, adjectives, and adverbs.

  • Shannon decided to go out for dinner.
  • Where would you like to place this vase?

When a word is inserted in between the “to” and the verb, the phrase becomes a split infinitive. Here’s one you might recognize:

  • Her mission? To boldly go where no man has gone before.

In this famous Star Trek quote, the infinitive “to go” is split by the adverb “boldly.”

The Case Against Splitting Infinitives

Splitting infinitives has been considered grammatically incorrect since the 1800s. The reasoning is that splitting an infinitive interrupts the thought it prevents, which can confuse the reader.

In formal writing, it’s best to avoid splitting infinitives by rewriting the sentence to put the descriptor either before the “to” or at the end of the sentence.

  • Split: Andy wanted to carefully consider his options.
  • Unsplit: Andy wanted to consider his options carefully.

Unfortunately, in more complex sentences, moving the descriptor can make it unclear which verb it applies to. You can avoid this by placing the descriptor immediately after the infinitive, but this can simply make the sentence more awkward to read.

  • Split: Jenny ran to quickly solve the computer problem.
  • Unclear: Jenny ran quickly to solve the computer problem.
  • Awkward: Jenny ran to solve quickly the computer problem.

When to Use “Not” and an Infinitive

When using “not” as the splitting descriptor for an infinitive phrase, the key is emphasis. Split infinitives, as we discussed above, are unusual in English, which makes them slightly jarring for the reader. This jar can sometimes be desirable in informal writing. If you’re trying to place the emphasis of the sentence on the verb in the infinitive, then splitting it with “not” can achieve that.

Here’s an example:

  • Sam decided not to eat the week-old gas station sushi.
  • Sam decided to not eat the week-old gas station sushi.

In the first version of the sentence, it is implied that Sam had no intention of eating the sushi at all. In the second, the shift in emphasis from “decided” to “not” suggests that Sam considered eating the sushi, but chose not to.

Using “not” to split an infinitive can be useful in comedic or sarcastic writing, but, as with any split infinitive, should be avoided in more formal pieces.


Split infinitives haven’t always been taboo, and it looks like they won’t always be. Even Merriam-Webster has begun to accept the unusual phrasing, advising their readers to daringly split infinitives if they really want to.

If you find that your sentence is clearer or easier to read when you split an infinitive with “not,” then do so. Just be aware of your audience.