BizWritingTip reader: “Will you please clarify the correct use of ‘that’ versus ‘which’ in qualifying sentences? It seems to me people often use ‘which’ when they should be using ‘that.’ ”
BizWritingTip response: It’s interesting that I have received three separate requests for this information in the past two weeks. So although I have dealt with this question before, I will discuss it again.
Basically, the use of “which” versus “that” is subjective. It’s all about what the writer wants to emphasize.
“Which” indicates that the thought following is not essential to the meaning of the sentence. The word “which” is preceded by a comma. That’s why you often get a green squiggle under the word. It’s to remind you to insert a comma before “which” (or to change the word to “that”). Unfortunately, your computer cannot tell you where to place the second comma if the non-essential thought is in the middle of the sentence. But you do have to add it.
The manager referred to a document, which is often quoted by others, to strengthen his argument. (Two commas must be added as the non-essential phrase — beginning with “which” — is in the middle of the sentence.)
I have enclosed a brochure, which will answer many of your questions. (Only one comma is needed because the non-essential phrase ends the sentence. The emphasis is on the brochure.)
“That” indicates the thought following is essential to the sentence. Never put a comma before or after “that.”
The manager referred to a document that was written some years ago.
The proposed legislation will affect all services that involve food distribution.
I have enclosed a brochure that will answer many of your questions. (The emphasis is on the brochure’s purpose.)
Note: Many people consider “that” a useless word. You can often tighten your sentence by deleting it.
The manager referred to a document written some years ago.
The proposed legislation will affect all services involving food distribution.
To summarize, “which” and “that” are often interchangeable depending on the point you want to emphasize. Just remember to always put a comma before “which.” Never put a comma before “that.”