Have you ever been writing or editing, and wondered about which of these fits best? For me, the question usually comes up during editing, and for a long time I’ve wondered about the answer. It’s a tricky one, and to be honest, I’m still figuring it out myself. But after reading up on it, I think I understand.
If you’ve never really thought about this problem, read these two sentences. To most people, either option sounds fine. Neither of them rings obvious warning bells. So which is right?
“They stare at ghosts or demons that only they can see.”
“They stare at ghosts or demons which only they can see.”
THAT – used to introduce a restrictive clause.
What is a restrictive clause? It’s something essential to the meaning of the sentence. If we remove the restrictive clause, the sentence no longer has the same meaning. Its meaning changes. Think of it like restricting the meaning of your sentence to something more specific.
It is uncomfortable to sit on chairs that don’t have cushions.
It is uncomfortable to sit on chairs.
Once we take out the restrictive clause, suddenly we’re talking about ALL chairs in a very broad sense, which of course changes the meaning. Saying “chairs like this” versus “all chairs” is very different.
WHICH – used to introduce a non-restrictive or parenthetical clause.
The non-restrictive clause is, of course, the opposite of before. If you cut out this part of the sentence, there is no change in the essential meaning. We might lose a detail or part of the description, but the sense is still basically the same. Usually, these phrases will be in parenthesis or have a comma before and after, since they are like an addition of detail to the sentence.
I sat on an uncomfortable chair, which was in my office.
I sat on an uncomfortable chair.
Notice that this time, if you take out that non-restrictive phrase, no damage is done to the sentence. In both, you sat on an uncomfortable chair. You were just more specific about which uncomfortable chair in one of them.
Here are the two side-by-side. Both are grammatically correct, since they have different meanings. Think about how the meaning changes between the two.
My car that is blue goes very fast.
My car, which is blue, goes very fast.
In the first sentence, the blue car is the fast one. By using “that,” you’re implying that you have more than one car and perhaps the other car isn’t as fast. But in the second one, you only have one car and you’re clarifying that it’s blue.
So, back to my original question, can you figure out which sentence right?
“They stare at ghosts or demons which only they can see.”
Why? Because the “only they can see” part is just a detail of the ghosts/demons. It doesn’t change that the ghosts/demons are there, and the subject “they” are staring at them.
If you’re still confused, sometimes it helps to read another wording or more examples. Here are my sources for further reading and more sample sentences:
