One clear lesson about language is that it's ever-evolving, yet at the same time, the more things change, the more things stay the same. Take the case of whom. It's a word that's been complicating things and confusing speakers and writers of the English language for ages. It's come up yet again in an Economist Language blog post in which R.L.G. asks, "Is Whom History?" This question was inspired by a 4-year-old girl correcting her mother, "Mama, sometimes you say a weird word, 'whom', when what you should be saying is 'who.' 'Whom' is not a real word."
Whom has been shuffling off this linguistic coil for years, or threatening to do so. But like cursive, is it really, finally, probably, maybe moving from endangered to very nearly extinct? Are whom's days numbered? Also: Do any of us remember how to use it properly anymore, anyway? (A quick Merriam-Webster review: it's "used as an object of a verb or a preceding preposition <to know for whom the bell tolls — John Donne> or less frequently as the object of a following preposition <the man whom you wrote to> though now often considered stilted especially as an interrogative and especially in oral use." Note, also, that "observers of the language have been predicting the demise of whom from about 1870 down to the present day." In May, following the New Yorker's Joan Acocella's annoyance at the idea that the whom/who distinction might be dying, Language Log's Mark Liberman reprinted James Thurber's hilarious 1929 thoughts on who versus whom:
The usage to be preferred in ordinary speech and writing is "Who are you, anyways?" "Whom" should be used in the nominative case only when a note of dignity or austerity is desired. For example, if a writer is dealing with a meeting of, say, the British Cabinet, it would be better to have the Premier greet a new arrival, such as an under-secretary, with a "Whom are you, anyways?" rather than a "Who are you, anyways?" - always granted that the Premier is sincerely unaware of the man's identity. To address a person one knows by a "Whom are you?" is a mark either of incredible lapse of memory or inexcusable arrogance. "How are you?" is a much kindlier salutation.
Grammar Girl Mignon Fogarty clarifies as to the appropriate use:
So remember, you use "whom" when you are referring to the object of a sentence. Use "who" when you are referring to the subject of a sentence.For example, it is "Whom did you step on?" if you are trying to figure out that I had squished Squiggly. Similarly, it would be "Whom do I love?" because you are asking about the object -- the target of my love. I know, it's shocking, but the Rolling Stones were being grammatically incorrect when they belted out the song "Who Do You Love?" which I think was originally written by Bo Diddley.
She adds this handy tip: "If you can't remember that you use 'whom' when you are referring to the object of the sentence, just remember that 'him' equals "whom." I love him (or her) = whom do you love?, for example. Need more help? Here's an instructive chart. Thurber adds, "it is better to use whom when in doubt, and even better to re-word the statement, and leave out all the relative pronouns, except ad, ante, con, in, inter, ob, post, prae, pro, sub, and super."