JS Tip 87: From the Writing Workshops: Using “That” and “Which”
Our friend Heidi Scott, a Credit Administrator with Zions Bank, asked if we could do something on using “that” versus “which” and when to use them.
We can do that.
Our Short Answer is it makes no difference.
The Reference Book calls it, “A fading difference. The words are interchangeable now.”
Our Long Answer provides some background.
There was a rule, a long time ago, that you should use “that” with restrictive clauses (“need-to-know” information) and “which” with non-restrictive clauses (“nice-to-know” information).
Consider the difference between these two sentences:
1. The boat that had a hole sank.
2. The boat, which had a hole, sank.
The first sentence addresses one boat of many. It identifies the particular boat that sank: the one with a hole in it. There were lots of boats in the marina that night, but the one with the hole went down. Glub glub.
That it had a hole differentiates it (restricts it) from the others. This is need-to-know information.
The second sentence addresses one boat alone. If it had a hole, that’s nice-to-know information, but not critical. Not restrictive.
But notice how the second sentence encloses the nice-to-know information in commas. You can use commas, dashes, or parentheses:
a. The boat, which had a hole, sank.
b. The boat—which had a hole—sank.
c. The boat (which had a hole) sank.
These commas, dashes, and parentheses (leading to the term “parenthetical remark”—nice-to-know but not need-to-know) make it easier to identify nice-to-know information.
So the difference between “that” and “which” has faded. Don’t worry about it.
Keep your questions coming. We love this stuff.