LAST week The Economist considered the new South African president’s in-tray, advertising our advice on the cover with the words “Who Cyril Ramaphosa should fire”. Some readers might have wondered whether someone should fire our proofreaders. Shouldn’t that be “Whom Cyril Ramaphosa should fire”?

It wasn’t a cock-up. On its face, our editors agreed, the grammar was clear. It should be whom. Who is used for subjects, whom for objects, including direct objects such as that of the verb to fire. “He fires him”, not “He fires he”. Thus, “He fires whom”.

The issue is not as simple as that. Whom is one of the few remaining vestiges of case in English. At the time of “Beowulf”, the great monster-slaying Anglo-Saxon epic, English nouns, pronouns and adjectives, plus words like the, all had an ending showing case. Four different cases in Old English tell you whether a word is a subject, direct object, indirect object or possessor. Other languages, from Ancient Greek to Russian to Estonian, have far richer case systems still.

More than 1,000 years later, that system has vanished almost entirely—probably fatally weakened by foreign invaders. When foreign speakers learn a second language, as the Vikings and then the Normans did when they conquered England, cases are tricky to pick up, as any student of Russian knows. If they can be dispensed with, they often will be. Those Vikings and Normans feebly learning Old English helped turn it into Middle English, in which case was far less often visible.

Yet fans of whom might ask, how can you dispense with case without throwing out intelligibility? It’s important to know what word in a sentence is the subject, which the direct object, and so on. That is true—so true that every language on Earth has a way of solving the problem, whether it has cases or not. In English and other case-poor languages, from Swedish to Vietnamese, the solution is word order.

In Old English, Latin or Russian subjects, objects and other words can appear in different orders; this gives speakers and writers a way to play with rhythm and emphasis. The loss of case in modern English means that word order must be relatively fixed, usually subject, verb and object in that sequence. Steve loves Sally means that Steve is the lover, Sally the loved. This could be reversed in Old English, with the meaning unchanged, because the case-endings would show who loved whom.

In English today just six words still show a distinction between subject and object: I, he, she, we, they and who. For the first five, making the case-distinction is mandatory nearly all of the time. You cannot say “I love she and she loves I”. Admittedly, some people say “between you and I”. (It should be between you and me, because both you and me are objects of the preposition.) But this is a marginal mistake, made mostly by educated people taking to excess the childhood lesson not to say “you and me” in sentences such as “you and me are going to be friends.” Regardless, that children say “you and me are going” and grown-ups say “between you and I”, and both are perfectly understood, illustrates the point: case just isn’t important to meaning in English.

Whom is special. It is used in questions and relative clauses, which are rarer and more complex than “he saw him” type sentences. It is not always obvious whether the relevant word is a subject or an object, as in sentences such as, “He’s the candidate who(m) we think will win”. (It should be who.) Perhaps because these sentences are tricky, and swapping who and whom rarely causes confusion, the two words have been collapsing into just one combined form: who, which is used, just like you, as both subject and object.

Whom is stuffier in some places than in others. The pomposity of Sideshow Bob from “The Simpsons” is clear when he asks his audience “Whoooom do you love?” By contrast Twitter recommends “Who to follow”. (Changing the site language to British English oddly changes this to “Whom to follow”, though Britons do not actually use whom any more than Americans.) After a preposition, whom still feels necessary: “people for whom a holiday is a far-off dream”. But in cases like our cover flash, “Whom Cyril Ramaphosa should fire” felt so unacceptably stilted that our editors decided against it.

The case, as it were, is getting stronger against whom. Except in the most formal language—think courtrooms and prayers—this little word may not survive. For whom, the bell tolls.