Split Infinitive

A PDF version is also available: Split Infinitives_Grammar Badgers

Split Infinitives 



The infinitive is the form of the verb that has the marker to in front of it, as in to walk, to run, and to go.

To split an infinitive is to put a word or words between to and the verb itself.

Take a look at the following often-quoted phrase from the Star Trek series

“Its continuing mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no one has gone before.”

(Star Trek, 2009)

Here, the infinitive to go is being split by the adverb boldly.



The split infinitive has occurred in the English language for a long time, but the structure fell out of use in written language until the end of the 18th century. The “rule” against splitting infinitives appeared in the 1800s, but it wasn’t initially put forth as a rule.

There are two views on the origin of the proscription of English split infinitive.

  • Latin origin hypothesis: The eighteenth-century grammarian, Bishop Lowth invented the proscription of not to split an infinitive. This prescriptivism is based on the idea that English grammar should function in the same way that Latin grammar does. In Latin, an infinitive is a single word (i.e. there is no marker like ‘to’) and therefore it is grammatically impossible to split it.
  • Eighteen-century hypothesis: It is said the idea of not putting an adverb in the middle of an infinitive was introduced by Henry Alford, the Dean of Canterbury, in his 1864 book The Queen’s English. Alford didn’t state it as a rule though. Instead, in response to a correspondent who liked phrases such as “to scientifically illustrate,” he said he saw “no good reason” to split the infinitive. One reason Alford gave for his belief was that nobody was doing it (“this practice is entirely unknown to English speakers and writers”). However, in fact, distinguished writers, from the 16th to 18th century,  including Sir Philip Sydney, John Donne, Daniel Defoe, Thomas Cromwell, Lord Byron, F. Scott Fitzgerald, Elizabeth Gaskell, Benjamin Franklin, and Elizabeth Barrett Browning have used it.



The main principle in writing is to make it as easy as possible in a way that keeps logical thoughts intact. Since an infinitive expresses a single idea, it is better to keep an infinitive together if we can. However, we do not have to stick to this prescriptivism just to avoid a split infinitive.

  • If a split infinitive ruins a perfectly clear and natural-sounding sentence, then it is probably better to keep the infinitive together. See the example below:

(a) John is not allowed to loudly play the music.

(b) John is not allowed to play the music loudly.

The split infinitive makes the sentence (a) awkward and less clear.

  • When the sentence meaning does change, a split infinitive may be a better choice.

(c) The hikers neglected thoroughly to clean up the campsite.

(d) The hikers neglected to thoroughly clean up the campsite.

In this case, if we put the adverb thoroughly after the infinitive, we run the risk of mangling the meaning. In this case, the split infinitive is recommended if that’s the most accurate way to express an idea.

  • We can also split an infinitive when the adverb either needs emphasis or wouldn’t work anywhere else in the sentence.

(e) They’re expected to gradually come down in price to about $50 to $75 each.

(f) They’re expected to come down in price to about $50 to $75 each gradually.

Placing gradually anywhere else in this sentence would create awkwardness and confusion.

The suggestion also depends on what level of students you have:

  • If you have a beginning learner, you may want to suggest that they should not split an infinitive because it might create further confusion.
  • If you have an intermediate or advanced learner, on the other hand, you can let be them aware that split infinitives are prevalently and frequently used among English native speakers in their daily speech. However, instead of prescribing or proscribing the use, you may want to leave the choice up to your students.



  • Infinitives are often split when the adverb either needs emphasis or wouldn’t work anywhere else in the sentence.
  • When moving the adverb to the end of a phrase doesn’t cause confusion or change the sentence’s meaning, it’s a good idea to keep the infinitive intact.

Listen to Cassie Pilarski, a workplace ESL instructor at Literacy Network in Madison, talking about her experience with teaching split infinitive.