Who & Whom

Anonymous writes:

Help! As a grammar maven, you might have a suggestion on when I should use "who" and when should I use "whom"? This is certainly a sticky wicket! Thanks for your advice!

I didn't intend to become the Grammar Answer Man, but since Mr. Nonymous was the first to post a comment of any kind, I can't help but oblige.

The difference between who and whom is a matter of case. There are three cases for personal pronouns: nominative, objective, and possessive.

I'll use the first person singular pronoun as an example:

nominative case: I (I love my Chihuahua.)
objective case: me (My Chihuahua loves me.)
possessive case: my and mine (I am my Chihuahua's and she is mine.)

The nominative case is used when the pronoun is the subject of a verb.
The objective case is used when the pronoun is an object--either of a verb or a preposition.
Possessive case pronouns are used to show...um, possession...duh. That's enough about possessive case anyway--it's never an issue.

Circumnavigating back to the original question, the pronoun who is the nominative case form and whom is the objective case form (whose is the possessive case, fyi). Which means you use who when it's the subject of the verb:

Who decapitated the Barbie?

And whom is used as the object of verbs and prepositions:

The elephant stampede trampled whom?
Do not ask for whom the bell tolls.

Which is why it is correct to write "To whom it may concern" (whom is the object of the preposition to).

A note of caution: Watch out for tricky little things called predicate nominatives. Predicate nominatives usually look like the objects of verbs, but they are not. They follow linking verbs like am, is, are, and the other be verbs. Linking verbs, you see, don't have objects, ever. A predicate nominative renames or is an equivalent of the subject. It therefore always takes a nominative case pronoun--including who.

Example: The ventriloquist is who?

It may (or may not) help to insert the more common pronoun I or me in the sentence. If I would be appropriate, go with who. If me is right, you'll want whom:

I ate the guacamole. = Who ate the guacamole?
The guacamole ate me. = The guacamole ate whom?

Thus ends a rather boring, but hopefully educational post. Personally, I'd rather know where the heck an expression like "sticky wicket" comes from. Then again, maybe it would be better if I didn't know.