Deposit this statement into your memory bank:
Who is the subject, and whom is the object in a sentence.
The subject of a sentence is a noun or a noun substitute about which something is asserted or asked in the predicate (the predicate is the part of a sentence comprising what is said about the subject).
The object of a sentence is a noun or a noun substitute governed by a transitive verb, a nonfinite verb, or a preposition. A direct object is any noun or a noun substitute that answers the question What? or Whom? after a transitive verb. A direct object frequently receives or is in some way affected by the action of the verb. Example:
John hit the ball. (ball is the direct object of the verb hit)
Subject: Who hit the ball? John hit the ball.
Object: John hit the ball to Linda. Linda is the object of the verb hit.
I should define one more term: case. Case is the form of a noun or pronoun in a specific context that shows whether it functions as a subject, an object, or a possessive. We use the terms subjective case for the subject of a sentence and objective case for the object of a sentence.
The pronouns who and whoever are in the subjective case, meaning that they are used as the subject of a sentence. The pronouns whom and whomever are in the objective case, meaning that they are used as the object of the subject in a sentence. See direct object above.
Zzzzzzzzz . . . Right?
Wake up. There’s more.
To find the correct pronoun case in a sentence, you must determine whether the pronoun functions as a subject or an object. To do that, use these tests:
Test for who or whom in the subjective case
Example: I wondered (who, whom) would vote.
Test: Substitute he and him (or she and her): “He would vote” or “Him would vote.”
Answer: He. Therefore, because he is subjective, who, which is also subjective, is correct: “I wondered who would vote.”
Test for who or whom in the objective case
Example: Volunteers go to senior citizen centers hoping to enroll people (who, whom) others have ignored.
Test: Try using they and them at the end of the sentence: “Others have ignored they” or “Others have ignored them.”
Answer: Them. Therefore, because them is objective, whom, which is also objective, is correct: “Volunteers go to senior citizen centers hoping to enroll people whom others have ignored.”
I hope all this makes sense to you so you can apply these rules in your writing.
One final point: Some grammatically correct sentences sound too fussy. If a sentence that says “We had a minister whom everyone seemed to like” sounds that way to you, then recast the sentence:
Everyone seemed to like the minister of our church.
This is fascinating stuff, isn’t it? Now you can amaze your friends by explaining the proper use of who and whom to them. I know they will thank you for that. Surely most of them have lost sleep by wrestling with the who/whom dilemma.
To reward you for reading all this gobbledygook, here’s a limerick that might amuse you:
A certain young man never knew
Just when to say whom and when who;
“The question of choosing,”
He said, “is confusing;
I wonder if which wouldn’t do.”
— Christopher Morley