This is the passage that contains what may be the most famous split infinitive of all time:
Space… the Final Frontier. These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before.
to boldly go – The infinitive is to go. The adverb boldly splits it by coming between the “to” and the “go.”
So what’s wrong with that?
Although generations of grammarians have done their best to forbid the splitting of the English infinitive, their efforts have failed to stamp out the practice.
Because it can be split.
An infinitive is the basic form of a verb.
In many, if not most, languages, the infinitive is one word.
In English, however, the infinitive is made up of two words.
Here, for example, are some French, Spanish, and Latin infinitives and their English equivalents:
French: aller (to go) courir (to run) écrire (to write)
Spanish: beber (to drink) escuchar (to listen) hablar (to speak)
Latin: capere (to take) cupere (to desire) optare (to choose)
French, Spanish, and Latin infinitives cannot be split because they are expressed by one word.
There’s no point in forbidding English speakers to place a modifier between the “to” and the verb that follows it. They can do it, so they will.
Sometimes splitting the infinitive is the only way to express the thought to be conveyed.
Consider the following sentences.
I want to live simply.
I simply want to live.
I want to simply live.
Each of these three sentences conveys a different meaning.
I want to live simply. The thought is that the speaker wants to live without the trappings of affluence. The speaker prefers a simple life, perhaps like what Thoreau describes in Walden.
I simply want to live. Here the thought seems to be that the speaker wants to live as opposed to dying. Do whatever you have to do, Doctor. I simply want to live.
I want to simply live. The speaker is tired of going to work, worrying about responsibility. I’ve been a drudge too long. I want to simply live and not worry about tomorrow.
If the split infinitive coveys your intended thought and sounds idiomatic, leave it.
If the split infinitive sounds awkward or muddies your thought, rewrite the sentence.