Summary
Split infinitives—where an adverb or phrase interrupts the structure “to + verb”—have long been debated in English grammar. Although many modern style guides now accept them, some editors, examiners and publishers still view them as stylistically weak or formally incorrect.
This expanded guide explains the history and structure of English infinitives, why splitting them has traditionally been discouraged, how modern writers approach the issue, when split infinitives may be acceptable and how to rewrite sentences to preserve clarity without breaking the infinitive. It offers practical guidance for academic and scientific authors who want to maintain a polished, professional tone while adapting to contemporary linguistic norms.
By understanding both the grammatical logic and the stylistic expectations surrounding infinitives, writers can make informed decisions that improve precision, readability and editorial acceptance.
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Split Infinitives in Academic Writing: Rules, Exceptions and Best Practice
The debate over split infinitives is one of the most enduring controversies in English grammar. Once considered a grave error in formal writing, the split infinitive—the insertion of adverbs or other words between “to” and the base form of a verb—has become increasingly common in everyday speech, online communication and even some professional academic prose. Modern style guides are more flexible than their predecessors, and many writers now split infinitives without hesitation.
However, academic and scientific writing still demands a high level of clarity, consistency and stylistic precision. Because some reviewers, editors and examiners continue to view split infinitives as stylistically undesirable—or as indicators of rushed or inattentive writing—scholars must understand not only how infinitives work but also how to control their sentence structures to avoid unnecessary splitting. Even when a split infinitive is technically permissible, it may still weaken the authority or smoothness of formal prose.
This expanded guide examines the grammatical structure behind English infinitives, the historical origins of the “no-split rule,” the current editorial expectations and the practical strategies authors can use to avoid split infinitives without sacrificing meaning or readability.
1. Understanding What an Infinitive Is
In many languages, the infinitive form of a verb is a single word. Latin’s venire (“to come”), videre (“to see”) and vincere (“to conquer”) demonstrate how the stem and infinitive ending form a single unit. Because the infinitive is structurally indivisible, one cannot insert words within it.
English infinitives are formed differently. They are composed of two separate words—to + verb—as in “to come,” “to see,” “to conquer.” Although these two elements are written separately, they still represent a grammatical unit. For centuries, grammarians argued that the unity of meaning should be reflected in the unity of structure: the components should remain together, uninterrupted, just as they are in single-word infinitives in other languages.
This logic led to the long-standing rule that infinitives should not be split. A phrase such as “to boldly go”—made famous by Star Trek—interrupts the infinitive and disrupts the conceptual unity of the verb. Traditionalists argue that such splitting weakens the grammatical integrity of the sentence.
2. Why Split Infinitives Became Controversial
The campaign against split infinitives emerged in the eighteenth and nineteenth centuries, when many English grammarians sought to model English usage after Latin. Because Latin infinitives cannot be split, prescriptive grammarians concluded that English infinitives should remain unsplit as well. This reasoning, while somewhat artificial, shaped academic and editorial conventions for generations.
For most of the nineteenth and twentieth centuries, the rule was strictly enforced in schools, publishing houses and universities. Writers who violated it risked criticism, corrections and claims of poor grammar. As a result, generations of scholars learned to avoid placing adverbs between “to” and the base verb, even when rephrasing required significant effort.
Today, linguists acknowledge that avoiding split infinitives is not an intrinsic grammatical rule but a stylistic preference inherited from prescriptive tradition. Modern usage guides often state that split infinitives are permissible when they prevent ambiguity or improve flow. However, resistance persists in certain circles, especially in formal academic contexts, where adherence to traditional standards remains strong.
3. Modern Usage: The Evolving Attitude Toward Split Infinitives
Contemporary writers frequently use split infinitives without noticing them: “to quickly analyse,” “to carefully review,” “to fully understand,” “to effectively communicate.” Because these constructions mirror natural speech patterns, they often feel intuitive and rhythmically smooth.
Some large publishing bodies now accept split infinitives when they improve clarity. Yet others—especially academic journals, editorial boards, grant committees and dissertation examiners—continue to perceive them as stylistically weak or imprecise. A split infinitive may not be “wrong,” but it may still draw negative attention from gatekeepers who value traditional formality.
Thus, academic authors should adopt a cautious, intentional approach: avoid split infinitives unless they contribute something meaningful to clarity or rhythm. Deliberate, sparing use signals stylistic control rather than reliance on conversational habits.
4. The Practical Problem with Split Infinitives: Perception
Whether or not a split infinitive constitutes a grammatical error is less important than the perception of correctness in academic writing. Scholarly work is evaluated not only for content but also for tone, style and precision. Writing that appears careless—however unfairly judged—may undermine an author’s authority.
A paper filled with split infinitives may be interpreted as informal, rushed or unpolished. Even a single prominent split infinitive may distract a reader who expects more traditional structures. By contrast, prose that maintains the unity of infinitives demonstrates careful sentence construction.
For authors aiming to produce high-level research writing, this consideration alone justifies avoiding split infinitives unless they are stylistically necessary.
5. How to Avoid Split Infinitives: Practical Rewriting Strategies
Rewording is often the best solution. In many cases, simply moving the adverb resolves the issue effortlessly:
• “to successfully write a book” → “to write a book successfully”
• “to quickly measure response rates” → “to measure response rates quickly”
These adjustments preserve meaning while respecting the traditional structure of the infinitive. Sometimes, however, avoiding the split infinitive requires more substantial restructuring. Consider:
• “The team aimed to rigorously test the hypothesis.”
Better: “The team aimed to test the hypothesis rigorously.”
Or:
• “The committee decided to formally approve the amendment.”
Better: “The committee decided to approve the amendment formally.”
These revisions require little effort but greatly improve formal tone.
In more complex sentences, repositioning the adverb may require shifting clauses or removing unnecessary modifiers. Although this sometimes results in longer sentences, the clarity and professionalism gained typically outweigh the minor increase in word count.
6. When Split Infinitives May Be Acceptable
Despite the benefits of avoiding split infinitives, there are rare situations where splitting may be the best option. These include:
1. Preventing ambiguity.
“to only report significant findings” (meaning exclusively report). Moving “only” may change the meaning: “to report only significant findings.”
2. Preserving natural rhythm.
In some cases, rigid avoidance can produce unnatural or awkward phrasing.
3. Avoiding misplaced modifiers.
If moving the adverb creates confusion, a split infinitive may be clearer.
Even in these cases, authors should weigh benefits against potential negative reactions from conservative readers or reviewers.
7. Striking the Balance: Intentional, Selective Use
Successful academic writers maintain conscious control over split infinitives rather than allowing them to appear accidentally. If a split infinitive genuinely enhances meaning or rhythm, it may be justified. But if a simpler, more elegant sentence is possible, it should be preferred.
Intentionality is the key. A deliberate split infinitive stands out as a stylistic choice; an accidental one stands out as an oversight.
Final Thoughts
Split infinitives may no longer carry the stigma they once did, but they remain stylistically sensitive elements of academic writing. Understanding how infinitives function, why the rule against splitting developed and how readers may perceive deviations helps scholars write more effectively and avoid unintentional distractions.
By learning when to avoid split infinitives—and when a carefully chosen one might enhance clarity—authors strengthen their mastery of English style and improve the professionalism of their manuscripts.
For authors who wish to refine sentence structure, improve clarity or prepare manuscripts for academic publication, our journal article editing service and manuscript editing service can provide expert support with grammar, style and formal presentation.
