This tip focuses on a pervasive yet unnecessary "rule" of English writing: the ban against splitting infinitives. While splitting infinitives is not often the clearest way to convey meaning, it should not really be considered "wrong" to do so.
First, let's define what is meant by splitting an infinitive. The infinitive is the basic form of a verb; in English, this form is made up of the particle to and the unaltered verb, as in to eat, to calculate, or to be. By convention, the two words that make up the infinitive are left together, without any word between. Splitting an infinitive, then, consists of introducing a word between to and the verb root, as in to defiantly stare or to boldly go.
In many other languages (including Latin, the favorite of many past grammarians), the infinitive is a single word and, thus, cannot be split. The same "rule" crept into English writing, despite the increased flexibility gained by having two words in each infinitive. In many cases, rearranging the sentence is possible, but sometimes splitting the infinitive is simply the best way to make your point. For example, when describing a company that is looking to increase its earnings more than twofold, it is clearest to say "They want to more than double their earnings this year," even if it splits the infinitive to double. Some publishers realize this fact and even provide support for split infinitives.
With all this being said, there are still a number of journals, editors, and reviewers who will tell you that it's incorrect to split an infinitive. (See the Journal of Virological Methods or Numen for examples.) What should you do if a journal forbids split infinitives? The short answer is to move the intervening text, which is usually just an adverb. That is, if your original sentence is written "It is impossible to completely purify the protein," moving the term completely to the end of the sentence will satisfy the journal's requirement: "It is impossible to purify the protein completely."
We hope this article has helped you understand what a split infinitive is and how to identify one if your target journal forbids it. In general, however, splitting infinitives is perfectly fine, so be sure to worry about them only if you have to. As always, send us your questions as emails to [email protected]. Best of luck with your writing!