The prime candidate for the stupidest invented rule in the entire history of the English language is the idea that there is something wrong with allowing a sentence to end with a preposition. We actually know the identity of the man who perpetrated this confidence trick, and we know when he committed the crime.
In 1670, John Dryden had just finished a tedious two-part ten-act play, a tragedy (all in rhyming couplets, which after the first hour must really make you feel you’re being beaten about the head with the poetry stick) about the Spanish victory over the Islamic rulers of Spain in the 15th century. It was called Almanzor and Almahide, or the Conquest of Granada. At the end of it he added a strange epilogue criticizing many of the other famous writers of the time, and saying that the English language was basically going to the dogs.
Critics did not like this epilogue much, but Dryden stubbornly added to the published version of his play in 1672 an essay in defense of it called ‘Defence of the epilogue’, giving more details of his criticisms of other writers. (Interestingly, in the second edition he took it out again.) Part of this essay attacked his rival poet and playwright Ben Jonson, who was as highly regarded as Shakespeare back then. Dryden quoted a phrase from Jonson’s play Catiline: His Conspiracy describing the mass slaughter at the end of the civil war in Rome; Jonson writes that as the souls of all the dead passed over into the underworld, there simply weren’t enough wild animals to eat all of the bodies that those souls were frighted from. (Frighted is just a 17-century word meaning ‘scared’.) Dryden wrote sniffily: ‘The preposition in the end of the sentence,’ ‘a common fault with him.’ (Later Dryden noticed that his own writing often had the same fault, so he set about fixing them up.)
But who had ever said it was a fault? Dryden provides no clue. It seems to have been just a whim of his. Yet somehow his baseless criticism stuck, and to this day there are teachers who believe that students should be taught not to use perfectly acceptable sentences of this sort:
They scarcely knew what they were looking at.
Machine learning is one subject I try to keep up with.
There’s no cinema in the town that I come from.
Prepositions left at ends of phrases or clauses positioned in this way are known as stranded prepositions. And astonishingly there are educated users of English (especially in the USA) who think sentences with stranded prepositions are bad, and struggle to avoid them.
The standard way people of avoiding stranding prepositions is to employ formal style, and shift the preposition to the beginning of the clause: instead of saying Who was the letter addressed to? you can write To whom was the letter addressed? (though it's not necessarily a good idea, because it sounds a bit pompous). However, that is a hopeless strategy for the first two examples above, and for the third it’s totally ungrammatical:
??They scarcely knew at what they were looking
??Machine learning is a field with which I try to keep up.
*There’s no cinema in the town from that I come.
Yet people who have somehow become terrified of grammatical sin will write (or even speak) hopelessly ungrammatical sentences as they struggle to avoid ending with a preposition. I have seen people writing truly grotesque sentences like ‘I hope you will understand of what I am speaking’ when they mean I hope you’ll understand what I’m talking about. I have read sentences using ‘impossible with which to comply’ when the simply meant impossible to comply with.
Once when I got no results from a search on the website of The New Yorker, the error message I got was: ‘I couldn’t find that for which you were looking’! They seemed to think that I couldn’t find what you were looking for would fall below The New Yorker's respectability standards. (They changed the error message a few weeks later after being mocked online.)
Let’s get one thing straight before we go on: the issue is actually nothing to do with prepositions ending a sentence, or a clause. A schoolteacher who wrongly thinks you shouldn’t write He hates any book that he is not the author of should be just as unhappy with Any book that he is not the author of displeases him. What they have in common is an instance of the preposition of which is not immediately followed by the NP object that of normally takes. The issue isn't about position in the sentence; it’s about types of clause in which prepositions are separated from their NP objects. That’s what stranding is.
Stranding is extremely frequent in open interrogative or relative clauses, and a few other kinds of clause. Here are a few examples, with ‘__’ marking the point in the sentence where an NP object would normally have been found. I underline to show the phrase that would have been in that position, and put square brackets round the crucial section of the sentence:
[Which restaurant did you go to __] for lunch?
If they don’t know [what the person died of __] they do an autopsy.
A person [who nobody likes __] is not a suitable candidate.
[What a ridiculous process we had to go through __], just to get permission to travel there.
But there are also examples where gaps follow prepositions and no wh-word is involved:
[That sort of thing, nobody will put up with __ any more.]
If there’s something [you’re not happy with __], then say so.
[An animal that you’re afraid of __] won’t be a very good pet.
I’ve got some pictures [for you to look at __].
These sentences are not grammar mistakes, and never were, no matter how far back you go in the history of English. Although languages like Latin, Spanish, and Italian don’t permit stranded prepositions, languages like Icelandic, Norwegian, and English do, and have done for a thousand years. Dryden’s idea that they were a ‘fault’ was an absurd eccentricity.
Robert Lowth was actually much less eccentric in his famous book A Short Introduction to English Grammar (1762). He commented correctly that preposition stranding was ‘an idiom which our language is strongly inclined to; it prevails in common conversation, and suits very well with the familiar style in writing.’ That’s entirely accurate (and he knew he was illustrating the point by writing ‘inclined to’. He also held the opinion that putting the preposition before the wh-phrase in a relative clause ‘is more graceful, as well as more perspicuous; and agrees much better with the solemn and elevated style’, and that’s also correct: someone we’re all indebted to is normal style, someone to whom we are all indebted is formal style. But as usual, formal style is not always what you want, and crucially, normal style should not be regarded as incorrect! Normal style is what you need to use most of the time.
Strunk’s Elements of Style in 1918 never said a word against stranding. It was E.B. White, in the chapter ‘An Approach to Style’ that he added to Strunk’s book when he revised it, who brought it up. White states correctly that the tool he murdered her with is preferable to the tool with which he murdered her, but gives an insane reason: he says that the first version, with stranding, ‘sounds more violent, more like murder’! White deludes himself. It doesn’t sound the slightest bit like murder when you whisper Tell me what you’re thinking about, or when you tell someone You’re the most interesting person I’ve ever talked to. They won’t think you’re about to reach for the claw hammer. White often talks nonsense about writing and style. You'd never think that from his fine writing in books like Charlotte’s Web, but some of his remarks about grammar and style are just nonsensical prattle.
White ignores his own ridiculous advice anyway (as he should). In Chapter 3 of Charlotte’s Web, when Wilbur the pig escaped through a fence with a loose board, but then decided he wanted to go back home, it says Homer Zuckerman ‘pulled the loose board away from the fence, so that there was a wide hole for Wilbur to walk through.’ The stranded preposition (through) isn’t there because White wants it to sound like murder! He’s just using normal style, like any sensible writer would.