When is it correct to use "whom" instead of "who"?

In traditional grammatical terms “who” is the nominative case and is used for the subject of a sentence or clause. “Whom” is accusative and is used for the object. In other words “who” corresponds to forms like “I”, “he”, “they”, etc; and “whom” corresponds to “me”, “him” or “them”.

Thus: “Who was at the party?” but “Whom did you see at the party?” (cf “She was at the party” and “Did you see her at the party?)

Similarly with the relative pronoun – “This is the man who saw me” and “This is the man (whom) I saw.” (cf “This is the man. He saw me” and “This is the man. I saw him.”

Things get complicated in more complex sentences. Some people write things like “She spoke about Shakespeare, whom she thought was over-rated.” In this case the pronoun should be “who”, not “whom”, as you can see if you reconstruct the sentence without it (“She spoke about Shakespeare. She thought HE was overrated”).

I would use WHOM as in...to whom is this letter addressed. I thought it was used as a dative object (indirect)

To whom is this letter addressed? (inverted for a question)

This letter is addressed to whom?

Subject="letter"
Verb="is addressed" (passive voice, action received by subject)
"to whom"=Adverb (how is the letter addressed?)
"whom"=Object of the Preposition (objective case)
"This"=Adjective (just so I don't leave one word out)

Bleh...back to English homework...

Whom is used in both the accusative and dative (direct and indirect object) cases:

Whom did she invite? (direct object)

To whom did she give the book? (indirect object)

"Whom" is also used as the object of prepositions -- "with whom," "of whom," "against whom," etc.

But, as TT points out, complex sentences can be confusing. You simply have to make certain that each verb has a subject:


http://www.grammarbook.com/grammar/whoVwhom.asp

I also would take issue with Tabby's last rule (and the stuff in the 'reference site'). The fact is that thinking, in the sense of considering, is a transitive verb, and therefore requires the accusative case for an object. Thus: 'She thought him very handsome'. (No one would ever say 'She thought he handsome'.) Hence: 'She loved John whom she thought very handsome'. Hence 'She spoke about Shakespeare, whom she thought was over-rated' is in fact correct.

But if you take it as 'who, she thought, was over-rated', then 'who' is correct. It depends whether you regard 'who/m' as subject of 'was over-rated' or object of 'she thought'. Personally, I'd go for 'who' in this one. You can also rearrange it as 'who was over-rated, she thought' which avoids the problem altogether.

I'll sack this keyboard... Don't ask me how, but I've got s instead of 's at the start of some phrases. Seeing as and ' are on opposite sides of the keyboard. I'm baffled. The / in who/m is supposed to be there.

If the subject of the sentence can be him or her use whom (m) for the him.

If the subject is he or she use who.

That's how I was taught who/whom agreement.

When knocking at the door, if someone asks "who is it?", they are incorrect. The correct question is "whom is it?", and the correct respose is not "It's me." The gramatically correct respose is, "it is I."

I agree with lammas1 that “she thought him very handsome” is perfectly grammatical (it’s like a Latin accusative and infinitive construction without the infinitive). Equally, “she thought (that) he was very handsome” is possible. Hence we get “She loved John, whom she thought very handsome” and “She loved John, who she thought was very handsome.”

Sorry, as I said, lots of English homework, so I've been hacking sentences to pieces for ages now.

Above it was said: "Hence 'She spoke about Shakespeare, whom she thought was over-rated' is in fact correct."
I disagree, and here's why...
Cut out the first clause "She spoke about Shakespeare"; it has nothing to do with the pronoun we're looking at.

Look at this independent clause and its dependent clause. "Whom she thought was over-rated." The introductory word of the dependent clause has been moved (very common). The sentence can be read "She thought whom was over-rated." Substitute "whom" with "him" and you get "She thought him was over-rated." Sounds very odd and foreign somehow.

If you want "whom" to be the direct object, you have to omit "was". (She thought whom/him over-rated.) Otherwise, you leave "was" hanging in space with no subject. The pronoun is the subject, and therefore must be "he" or "who". EVEN BETTER, add a commonly omitted word and voila: "She thought *that* who(he) was over-rated." The *that* doesn't fit in the inverted form (who she thought was overrated), so of course we omit it.

On another side line, you could make "whom" the subject of an infinitive. "Whom she thought to be over-rated." (She thought whom to be over-rated.) But as long as the pronoun is the subject of its own verb, it should be "who".

Another way of looking at it is that 'who/m' cannot be the object of 'she thought'. You cannot think a person, but you can think a thought. Nice one, Kayle, for bringing 'that' into it. Beat me to it. And sorry Bungee, but 'Whom is it' is way out of line, especially if you are objecting to 'it is me'. To be take the same person after it as is in front of it - there's no action. In common speech, one does say 'it's me', but 'It is I' is the correct if stilted sounding form. Therefore 'Who is it?' is also correct.

Just noticed 'she thought him very handsome'. I feel there is another case of omission there. 'She thought OF him AS very handsome'.