Myth #1: Don’t Split an Infinitive.
“Split” all you want, because this old superstition has never been legit. Writers of English have been doing it since the 1300s.
Where did the notion come from? We can blame Henry Alford, a 19th-century Latinist and Dean of Canterbury, for trying to criminalize the split infinitive. (Latin, by the way, is a recurring theme in the mythology of English grammar.) In 1864, Alford published a very popular grammar book, A Plea for the Queen’s English, in which he declared that to was part of the infinitive and that the parts were inseparable. (False on both counts.) He was probably influenced by the fact that the infinitive, the simplest form of a verb, is one word in Latin and thus can’t be split. So, for example, you shouldn’t put an adverb, like boldly, in the middle of the infinitive phrase to go—as in to boldly go. (Tell that to Gene Roddenberry!)
Grammarians began challenging Alford almost immediately. By the early 20th century, the most respected authorities on English (the linguist Otto Jespersen, the lexicographer Henry Fowler, the grammarian George O. Curme, and others) were vigorously debunking the split-infinitive myth, and explaining that “splitting” is not only acceptable but often preferable. Besides, you can’t really split an infinitive, since to is just a prepositional marker and not part of the infinitive itself. In fact, sometimes it’s not needed at all. In sentences like “She helped him to write,” or “Jack helped me to move,” the to could easily be dropped.
But against all reason, this notorious myth of English grammar lives on—in the public imagination if nowhere else.
This wasn’t the first time that the forces of Latinism had tried to graft Latin models of sentence structure onto English, a Germanic language. Read on.