grammar rules split infinitives

What are the grammar rules surrounding split infinitives?

It’s important that we, as writers, know the tools of our trade. Part of our job is to understand the mechanics of language, which includes grammar rules. Yet many writers find themselves asking…

What are split infinitives?

It’s a term that grammarians and linguists throw around a lot, yet few people, including writers, seem to know what it means.

According to Wikipedia:

A split infinitive or cleft infinitive is an English-language grammatical construction in which a word or phrase, usually an adverb or adverbial phrase, comes between the marker to and the bare infinitive (uninflected) form of a verb.

So, what’s an infinitive? What’s a bare infinitive? Understanding these terms will help us figure out what split infinitives are.

An infinitive, or bare infinitive is a simple form of a verb. Examples include write, go, talk, sit, and understand.

When a participle, such as to, appears before an infinitive, it is then referred to as a full infinitive. Examples include to write, to go, to talk, to sit, and to understand.

So, how do we get split infinitives?

Infinitives become split infinitives when another word is inserted between the participle (also called a marker) and the bare infinitive:

We want to truly understand English grammar.

In the example above, the participle is to and the bare infinitive is understand. The full infinitive to understand is split by the adverb truly.

That’s simple enough. So what’s the fuss?

As split infinitives became more popular in the 19th century, some grammatical authorities sought to introduce a prescriptive rule against them. The construction is still the subject of disagreement among native English speakers as to whether refraining from split infinitives is grammatically correct or good style.

In 1926, Henry Fowler wrote, “No other grammatical issue has so divided English speakers since the split infinitive was declared to be a solecism in the 19c: raise the subject of English usage in any conversation today and it is sure to be mentioned.” (source: Wikipedia)

Today, however, most linguists agree that split infinitives are acceptable.

Grammar Rules, Style, and Split Infinitives

While the grammar rules regarding split infinitives are being debated, style dictates that we write our sentences to be clear and consistent. Let’s take another look at our example sentence, but let’s move the adverb so our infinitive is no longer split:

We truly want to understand English grammar.

Note that this sentence sounds clearer, but we’ve changed the meaning. In the original example sentence, the adverb truly modified the phrase to understand. Here, it modifies want. When splitting infinitives, we need to make sure the word doing the splitting is modifying the right words in the sentence.

Let’s rewrite the sentence while keeping the meaning intact:

We want to master English grammar.

Here, the split infinitive to truly understand is replaced with stronger, more precise wording. Instead of truly understanding English grammar, we want to master it! This sentence is far clearer than the original. It has more punch, it doesn’t include a (somewhat questionable) split infinitive, and it communicates the exact same idea.

Split infinitives can sound awkward or clumsy when there’s a simpler, clearer way to construct the sentence.

The Final Frontier

One of the most famous of all split infinitives occurs in the opening sequence of Star Trek:


If you can find the participle (marker), the bare infinitive (simple form of the verb), and the adverb (which is causing the split) in the excerpt above, then you’re up to speed on split infinitives. Could it be rewritten without the split infinitive? Would it sound better or worse?

Now you know all about split infinitives. You know:

  • What split infinitives are
  • How to identify split infinitives
  • Split infinitives are acceptable, but
  • Split infinitives can make a piece of writing awkward, so
  • Use split infinitives with care

Do you better understand split infinitives? Have anything to add? Do you have any questions about these or other grammar rules? Share your thoughts by leaving a comment.

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