Links in this essay will take you to information about the usage experts and their work. Numbers in parentheses are page references in the sources.
who versus whom
A student once confided to his writing center tutor, "I'm sorry, but the wordwhom isn't in my vocabulary." Many teachers—even diehard purists—have empathy for such a student. Let's face it: Whom often sounds pretentiously correct. Also, to follow the rules, at least in conversation, speakers need a mental computer capable of analyzing complex grammatical structures faster than they can talk. Even in writing, getting who and whom straight can be tricky. Patricia O'Conner, who approves of the rules, admits that following them can require some detective work: "Miss Marple herself might have been stumped by the convolutions of some who orwhom clauses" (7).
Will the rules on who and whom die out for these reasons? Only time will tell. Currently, most usage experts, while acknowledging the difficulties, advise us to distinguish carefully between who and whom, at least in formal writing. Why might the distinction be worth preserving? Wilson Follett argues that the choice of the wrong form can cause a misreading. He offers the following example:
M. departed eight days later in humiliation as the man who, more than anyone else, the President had repudiated. (360)
The problem, says Follett, is that the incorrect who tells readers that the next significant word will be a verb: who . . . had done such and such. Whom would correctly tell readers that a subject (followed by a verb) will come shortly: whom . . . the President had repudiated.
Although usage experts are not ready to throw out whom, they admit that some of its uses are harder to defend than others. For example, whom seems natural enough when it comes right after a preposition (for whom the bell tolls), but it can sound stuffy when it appears in a sentence where readers expect a subject. Consider the following examples:
Whom did Alan go out with last night?
Whom do you think you're speaking to?
Whom you know counts more than what you know.
Whom is an object in each of these sentences, but the objective-case pronoun sounds unnatural because it is sitting in territory ordinarily occupied by the grammatical subject.
We could of course change the rules to match the way most people actually speak—keeping whom for some objects but using who for others—but few experts are prepared to endorse such a radical change. Editors need to have guidelines based on clear principles; to allow both who and whom to play the role of object would lead to much confusion. If such usage becomes accepted, says Theodore Bernstein, "grammarians will not . . . be able to explain it" (122).
Instead of tossing out or radically reworking the rules, the experts have decided to distinguish between formal and informal usage. Their conclusion: In informal speech and writing, we can break the rules, but in formal writing we cannot. Patricia O’Conner can have the last word: “There’s no doubt that in everyday speech, whom had lost the battle. . . . But since written English is more formal than conversational English, anyone who wants to write correctly will have to get a grip on whom” (6–7).
Source: Hacker Handbooks (Boston: Bedford, 2013).