As an editor, this is the #1 question I get. Is it OK to use split infinitives?
Lots of sources provide conflicting opinions. Many, like Oxford English Dictionary’s Language Matters, say “yes.” But, I say “no.”
Sure, split infinitives have become a part of American English convention. But, that does not mean using them is correct or the best way to get your point across.
A split infinitive occurs when an adverb is inserted between “to” and the verb. On its page on split infinitives, Oxford English Dictionary’s Language Matters gives the following example:
#1 You have to really watch him.
Oxford then explains that the grammatically correct structure of this sentence is:
#2 You really have to watch him.
However, as Oxford explains, the two sentences have different meanings, with sentence 1 emphasizing a need to focus on him and sentence 2 emphasizing the urgency of watching. Oxford likens sentence 2 to #3 “You have to watch him very closely.”
So, I ask, why not just use sentence #3? Not only is it grammatically correct, but it more clearly conveys the emphasis of the sentence. See? Split infinitives are not necessary.
When you find yourself leaning toward using one, write and rewrite until you get it right. And, never use one again!
Edit April 2, 2019: The featured photo, above, was created by Nick Lowndes for The Economist. While I absolutely love the photo, I realize the irony in my posting it considering that the article directly opposes my position above. Consider this my attempt to show you that there are many opinions on language, and not all of the are correct. Except mine. Mine is always correct. 😉