Over the years I’ve mentioned all four of these incorrect rules, both in the classroom and on this blog. Use the search box in the upper right to find several mentions of each bad rule.
What English language rules are incorrect?
Never split an infinitive
Never end a sentence with a preposition
Never use a double negative
The pronouns “them” and “they” are always plural, never singular
I had forgotten the source of these rules. I think he was mentioned once in my sophomore English class. But I have long known that these rules were bad. Anyway, here’s an essay from Quora on the subject. It was written by Franklin Veaux, published author and compulsive writer. Thank you, sir, for the reminder.
All four of these rules were made up by one person, Bishop Robert Lowth.
Lowth was a religious scholar who was obsessed with the “purity” and perfection of Latin. He had a big-time fetish for Latin grammar. He considered Latin the ideal language, and believed that English should be more like Latin.
In 1762, he published a book on English grammar that made up a whole bunch of new rules, including the four above. His sole rationale for many of these rules was simply to try to force English grammar to be closer to Latin grammar.
Those rules had never been part of English until he made them up, and outside of prescriptivist grammar taught in school, they never caught on. Today, English grammar experts have largely abandoned teaching any of them.