No, split infinitives are not wrong. Placing an adverb between to and its verb — as in to boldly go — is fully grammatical and has been ordinary English for roughly 700 years. The belief that it's an error is a Victorian myth borrowed from Latin, and today every major usage guide rejects it. The practical rule: split an infinitive whenever it reads more clearly or naturally, and only rearrange to avoid a split if you're writing for a reader you know to be a stickler.
What is a split infinitive?
An infinitive is the base to + verb form of a verb: to go, to run, to decide. You "split" it by slipping a word — almost always an adverb — between to and the verb:
- to quickly decide
- to really understand
- to boldly go where no one has gone before
Strictly speaking, the name is a misnomer. The infinitive is really just the verb (go); the to is a separate little signpost that usually sits in front of it. So there is no single unit being "broken" — which is the first clue that the prohibition was never built on solid ground.
Where the "rule" came from — and why it's a myth
Split infinitives are not a modern slip. They appear in Middle English — in Layamon's Brut (early 1200s) and in Wycliffe's writing in the 1300s — and they run right through the work of Donne, Defoe, Benjamin Franklin, Wordsworth, Byron, George Eliot, Henry James and Abraham Lincoln.
The ban is a nineteenth-century invention, and its source is Latin envy. In Latin, an infinitive is a single word — amare ("to love"), ire ("to go") — so it is physically impossible to split. Victorian grammarians who treated Latin as the perfect language decided English ought to imitate it. Dean Henry Alford's popular A Plea for the Queen's English (1864) spread the objection, dismissing the split as "a practice entirely unknown to English speakers and writers" — which was simply false. The term split infinitive itself wasn't even coined until 1897.
The flaw is obvious: English is not Latin. To go is two words, and English has always allowed an adverb to nestle between them. Modern authorities are unanimous. The Chicago Manual of Style notes that "although from about 1850 to 1925 many grammarians stated otherwise, it is now widely acknowledged that adverbs sometimes justifiably separate the to from the principal verb." Merriam-Webster is blunter: "the objection to the split infinitive has never had a rational basis." Garner's Modern English Usage calls the never-split rule a "superstition."
✓ Clear vs ✗ awkward: examples
Because splitting is never actually ungrammatical, the ✗ sentences below aren't "errors" — they're the awkward or ambiguous versions that writers produce when they contort a sentence to dodge a harmless split.
- ✓ She asked him to gently close the door. — clear: close it gently.
- ✗ She asked him gently to close the door. — now it sounds as if she asked gently.
- ✓ He failed to completely understand the plan. — he didn't fully grasp it.
- ✗ He failed completely to understand the plan. — ambiguous: did he fail completely, or understand completely?
- ✓ Profits are expected to more than double this year. — natural and instantly clear.
- ✗ Profits are expected more than to double this year. — barely English; here the split is effectively required.
- ✓ To boldly go where no one has gone before. — famous for a reason.
- ✗ Boldly to go where no one has gone before. — stilted, and it kills the rhythm.
Watch what happens when you simply shove the adverb elsewhere: I want to really know you and I really want to know you are different sentences. In the first, really intensifies the knowing; in the second, it intensifies the wanting. Moving an adverb out of the split can quietly change your meaning, so don't do it on autopilot.
When you might leave the infinitive intact
There are a few honest cases for not splitting:
- Long intervening phrases. A single adverb is invisible; a whole clause stalls the reader. ✗ We hope to, if the weather holds and the ferry runs, reach the island by noon. → ✓ We hope to reach the island by noon, if the weather holds and the ferry runs.
- Gratuitous splits. If a sentence reads exactly as well unsplit, there's no prize for splitting — but equally, no need to twist it into knots to avoid one.
- Sticklers in the room. In some formal, legal, academic or exam settings, a reader may (wrongly, but firmly) treat a split as a mistake. Write for that reader, not for the imaginary rule.
One special case: negation. The board voted to not renew the contract and The board voted not to renew the contract are both fine, but not to is usually smoother. It's the one split that often reads better left unsplit.
A memory trick
Just remember to boldly go. Star Trek split its infinitive on purpose in 1966, and the line became one of the most famous sentences in television history. When The Next Generation updated the narration in 1987, the writers changed "no man" to "no one" — but they kept to boldly go, because both to go boldly and boldly to go sound worse. If a split infinitive is good enough for the starship Enterprise, it's good enough for your email. The rule of thumb: put the adverb where it sounds most natural when you read the sentence aloud — and nine times in ten, that's right between to and the verb.
US vs UK: is there really a difference?
Not much — and not the difference people expect. The split is treated as a myth on both sides of the Atlantic. American authorities — the Chicago Manual of Style, Garner's Modern English Usage and Merriam-Webster — are firmly pro-split. So are the British ones. Fowler, the most-quoted British usage writer of all, famously sorted English speakers into five classes over this very question: "those who neither know nor care what a split infinitive is; those who do not know but care very much; those who know and condemn; those who know and approve; and those who know and distinguish." Fowler placed himself in that last group — split when it helps, don't when it doesn't.
The one small transatlantic wrinkle is a lingering institutional caution in Britain. The Economist's style guide long took a resigned line: "Happy the man who has never been told that it is wrong to split an infinitive: the ban is pointless. Unfortunately, to see it broken is so annoying to so many people that you should observe it." Even that has since softened, now telling writers to split when moving the adverb "would ruin the rhythm, change the meaning or even just put the emphasis in the wrong place." So the takeaway is the same everywhere: the grammar permits the split every time. The only real question is whether your particular reader is a stickler — and that's a question about your audience, not about English.
