Those who have little interest in language will often point to a rule like the difference between who and whom to argue how unimportant grammar really is: whether I say the doctor who I saw last week or the doctor whom I saw last week, you know what I mean, they’ll say. And there’s no arguing that point if language is thought to be just a blunt instrument to turn someone’s attention to what’s going on in simple and obvious situations. One does wonder, though, whether settling for the big and obvious isn’t blinding us to the small and subtle. Is blunt language really blunting reality?
Be that as it may, take, for example, this not unusual sentence: she saw Peter more often than me. Does the writer intend to say that she saw Peter more often than I saw him, or that she saw Peter more often than she saw me? Much depends on the grammar, perhaps even heartbreak. And would I say, I thought there was something between you and I or I thought there was something between you and me? What is at issue here (other than impending sorrow) is the grammatical phenomenon called case, a woefully bland word for an interestingly intricate device that is beyond none of us.
Case refers to the way in which a word changes its spelling or position in a sentence to indicate its grammatical function. Modern English has three cases (be thankful, German has four, Russian six, and Finnish 15), and they’re called the nominative, the possessive, and the objective. Each case carries out certain grammatical functions: the nominative case shows the subject, the possessive shows the possessor of something, and the objective shows the object of a verb or a preposition. Case applies to nouns, pronouns, and adjectives, but it’s always best to see how it works in the pronouns, where the changes are clear cut.
The personal pronoun I, for example, has three forms, I, my, me, and those three forms represent the three cases. Likewise, the three cases of the personal pronoun she are she, her, and her. And with that information, we can create all manner of statements to organize reality. In the sentence she saw me, for example, you will know that she was the one seeing and I was the one seen—because the subject of a sentence is in the nominative case, she, and the object of a verb is in the objective case, me. Or we could turn reality on its head by simply changing the case: I saw her. And the preposition between in the sentence I thought there was something between you and me must have me, not I, as its object, because objects are in the objective case, not the nominative. No confusion, no argument.
And who and whom work the same way. The mystery of mysteries here is no more recondite than that who is the nominative form and whom the objective. These two words are relative pronouns, which means they always point to some noun in a previous clause. So if I wanted to tell you that I saw a doctor last week and that doctor was caring and attentive, I could construct these ideas in a complex sentence: The doctor whom I saw last week was caring and attentive. The verb saw needs an object, objects are in the objective case, and whom is the objective case of who. Done.
And what about she saw Peter more often than me? The pronoun she is clearly nominative, so that must be the subject of the verb saw, and Peter is an object of saw because it stands after the verb. This is an example of case by position, not spelling, because nouns, unlike pronouns, do not change their spelling to distinguish between their nominative and objective cases. But what about me? Well, we know that the spelling me can only mean the objective case, and in this sentence that would mean that me is another object of the verb saw—which really means, sadly, that she saw Peter more often than she saw me.
And thus it is that grammar can tangle the heart.