On the heels of my post about when to use “who” vs. “that,” today I thought I’d address an equally thorny differentiation: “that” vs. “which.”
Mind you, somehow I managed to receive a degree in English without learning the difference between “that” and “which,” so don’t feel bad if you have no clue. It wasn’t until I was in graduate school that my friend Debbie laid it out for me, clear as day.
Here’s what she said: If it sounds like you could use either, use “that.”
*Cooking is an activity that relaxes many people (CORRECT)
*Cooking is an activity which relaxes many people (INCORRECT)
In the above sentence, to the untrained ear it may sound like you could use either. So given Debbie’s justification, “that” would be the correct choice. And guess what? It is!
Wanting a more formal explanation for what Debbie had told me, shortly after our conversation I did some research, and here’s what I learned:
Essential clauses, which can’t be removed from a sentence without changing its basic meaning, require “that”:
*Cooking is something that I do all the time.
If you remove the essential clause above, you’ll be left with:
*Cooking is something. (CHANGES BASIC MEANING OF SENTENCE)
Nonessential clauses, which can be removed without altering the basic meaning of the sentence, require “which.” (Note: these type of clauses, such as the ones I’ve written above, are set apart with commas.)
*Cooking, which I love, is relaxing.
If you remove the nonessential clause above, you’ll be left with:
*Cooking is relaxing. (DOESN’T CHANGE BASIC MEANING OF SENTENCE)
Got it? I know this is tricky, so if you’re more confused than ever, see if the clause in question is set apart by commas. That should help you figure it out!
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