A split infinitive verb (or simply split infinitive) is a verb in the infinitive form (which in English is two words) with another word (usually an adverb) placed in the middle. The infinitive form is the most basic form of the verb, the one without any tense. You can think of the infinitive form as the root form or foundation form since all verb forms outside the infinitive are merely transformations of the infinitive form.
Most languages have infinitive verb forms that comprise only one word. However, in English the infinitive form is two words. Take, for example, the Spanish word esperar, which means to wait. Both esperar and to wait have the same meaning and are infinitive verb forms. But esperar is just one word, while to wait are two words. Thus, the problem of split infinitives is really unique to English, since splitting a single word is simply not done.
What exactly is the problem with a split infinitive? It’s structural and contextual. The infinitive form in English is two words, which means that both words act together as a single unit or package. Separating those two words from each other creates two separate units or packages, which has no functional legitimacy in the structure of the sentence. Both words are needed in order for the infinitive form to perform its function within the sentence structure.
When writers divide a single functional unit, they create a context that conveys disorder and looseness. While appropriate in many types of informal writing, technical and other such professional writing requires more formality associated with more orderly, firm sentence structures. Introducing an inappropriate context to writing always makes for less effective writing.
Yet the appeal to use split infinitives remains strong because writers sometimes want to place special emphasis on a particular verb, especially when that special emphasis is considered part of the meaning intended to be communicated. That’s a large part why split infinitives abound in spoken English, a communication form with rather lax guidelines regarding structure. Written English, on the other hand, is a different animal.
Consider the example sentence in the graphic above. The phrase to simply note is a split infinitive and should be revised. The easiest solution is to swap the order of the first two words as follows:
When encountering split infinitives, I recommend experimenting with different placements of the adverb which splits the infinitive. I would then select whichever option appeals most. For our example sentence, this procedure would yield
The procedure is simply to note which lights turn red at what times.
The procedure simply is to note which lights turn red at what times.
Whichever option appeals most to you, simply don’t split infinitive verbs. This one guideline alone can make marked improvements in your technical and other such professional writing. And better writing better represents both you as a writer and the brands connected with you.