, , , ,

Who vs. That vs. Which
(adapted from https://www.grammarbook.com/grammar/whoVwhVt.asp)

Rule 1: Who refers to people. That and which refer to groups or things.
More below on this…

Rule 2: That introduces essential clauses while which introduces nonessential clauses.
A clause is “essential” if taking it away seems to significantly change the meaning of the sentence—usually, taking out an essential clause leaves you wondering what the point was.

For example:
I want to find a job that allows me to exhibit my full range of weird imagination.
(Taking out the clause following “that” leaves: I want to find a job. Not the same sentence at all!)

On the other hand, nonessential clauses serve, basically, as adjectives:

I have a job already, which allows me to pay rent, but I don’t feel very fulfilled by it. And my current job does involve a bit more killing than I would prefer.

NOTE: Essential clauses do not have commas surrounding them while nonessential clauses are surrounded by commas.

Rule Three is sort of an add-on: it’s not really a rule as such, more a bit of special dispensation.

Rule 3: If this, that, these, or those has already introduced an essential clause, you may use which to introduce the next clause, whether it is essential or nonessential.

That is a decision which you must live with for the rest of your life.
Those ideas, which we’ve discussed thoroughly enough, do not need to be addressed again.

NOTE: Often, you can streamline your sentence by leaving out which.

That is a decision which you must live with for the rest of your life.
That is a decision you must live with for the rest of your life.

But in any case,
I want to find a girl that looks just like Ruth Bader Ginsberg. (Wrong: should be who)
My current girlfriend, which I like very much, looks more like Sonya Sotomayor. (Same)

Which should not start a sentence unless it’s used interrogatively!
Which should be obvious. (WRONG)    Which should be obvious? (Okay, if what I mean is, which (of several already discussed things) should be the obvious thing?)

Rule 4: If you’re using who, and it’s the object, not the subject, in the OUTER sentence, then use whom.

Rule 4a. You will rarely, if ever, get blamed if you use who instead of whom. But do NOT use whom when it should be who.


1. I did not know the person to whom the evil priest sent the plague of scorpions.

Here, the “who” is the object of the preposition “to.” Prepositions (in, to, with etc) take direct objects.

Substitution check: Try replacing the clause (whom the evil priest sent the plague of scorpions) with a pronoun:

I did not know him… I did not know he. Well, obviously “him” is right and “he” is wrong, so (since him, like her or me or us, is an object pronoun) use whom.

2. You never know who you will see at the evil temple.

Really, this who is the object of the verb know in the “outer” sentence (You never know them, you never know her etc) and so it should be whom. But it sounds just fine as it is.

3. With whom did he call up that plague of scorpions?

It’s the object of with, so it should be whom.

4. Whom is at the door?

No. Just no. This should be who. It’s the subject.

Whomever is the “-ever” version of whoever. (Whatever…!)


You may think that “whom” always sounds more elegant and educated than “who,” but using whom in the wrong place makes you sound, not just like an idiot, but like an idiot with a high opinion of him- or herself.

See if I use my grammar rules correctly at: