What are Split Infinitives?

中文

Star Trek has often been referenced in The Big Bang Theory, an American TV sitcom which I have been revisiting these days; and while William Shatner (aka Captain Kirk) made his guest appearance, it also reminded me of his famous quote in the original Star Trek TV series: “To boldly go where no man has gone before”. In this Ed’s Elevenses blog post, we will focus on structures like “to boldly go”, which are also known as split infinitives, and look briefly into why they have been a source of grammatical controversy for centuries.

What are split infinitives?

Split infinitives happen when you put an adverb (or an adverbial phrase) between to and the verb (i.e, the bare infinitive in the to-infinitive), for example:
➡️ I need to really think about it.
➡️ We expect the revenue to more than double in two years.

What are the different views?

Purists (in this case, linguistic prescriptivists) and some English language teachers would regard split infinitives as grammatically incorrect. For instance, the renowned textual critic, Henry Alford, who wrote A Plea for the Queen’s English: Stray Notes on Speaking and Spelling (1866), regards “the to of the infinitive as inseparable from its verb” (p. 188).

These people would rewrite these sentences as:
➡️ I really need to think about it.
➡️ We expect the revenue more than to double in two years.

and Captain Kirk’s:
➡️ Boldly to go where no man has gone before.
➡️ To go boldly where no man has gone before.

In fact, it has been suggested that such principal objections to the split infinitive mainly stem from the comparisons with the structure of classical languages, as an infinitive in Latin can never be split.

However, some grammar guides and major English dictionaries point out that such objections have not had a “rational basis” or a “real justification”. In Grammar of the English Language (1931), George Curme argues that split infinitives make expressions clearer and should be promoted; Martin Cutts, author of The Oxford Guide to Plain English (2009), also suggests that it may sometimes be preferable to split an infinitive.

To split or not to split?

As the OED notes that, while split infinitives are not ungrammatical, it may be best to avoid it—to quote Kenneth Wilson of The Columbia Guide to Standard American English (1993)—“when you’re uncertain of your readers’ expectations and sensitivities in this matter” (p. 411).

Personally, I believe it would be wise to check the meaning of the sentence before deciding to ditch split infinitives completely. Consider:

I need to really think about it.
= I need to think about it very carefully.

which does not have the same meaning as:

I really need to think about it.
= It is necessary for me to think about it.

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Edison Tam MA MCIL CL is a Translator, Proofreader, and Copyeditor (zh-hk/en) who works with students, independent non-fiction writers, academic researchers, and clients from businesses and organisations of all sizes.

He is Chartered Linguist and Member of the Chartered Institute of Linguists (CIOL), and has undergone wide-ranging academic training in Business, Modern Languages, and Applied Linguistics in Hong Kong, London, and Barcelona.