I feel the need to refresh readers on why I cover grammar topics when the attitude of many novelists is that ‘an editor will fix it for me.’ Because really, there is some truth to that—an editor won’t catch everything, but an agent or publisher isn’t going to turn you away just because you have a few “whiches” that should be “thats” and visa versa. However, understanding grammar allows a writer to break the rules more effectively, which is very different than ignoring them altogether. Persuant to the grammar message I started out with, the goal is to write with purpose not with indolence.
To begin with the topic in discussion, That vs. Which…it’s a common mistake that often gets ignored. Moreover, understanding the rule doesn’t mean it won’t be repeated as it’s an easy one to overlook. But with understanding comes improvement, so let’s dive in.
First, it’s important to recognize what each word (including the other main relative pronouns) refers to:
- That (to include these and those) and Which refer to groups or things
- Who refers to people
- Where refers to a location, and understand that (for instance) New York could be EITHER a location or a group depending on how it’s used in the sentence (as in the difference between, “New York, the city that never sleeps” and “New York, where citizens never sleep”)
- When refers to a point in time
Easy enough, right? What traps most people is when to use that and when to use which.
- That introduces an essential clause to the sentence.
Example: “I do not like cars that are red.”
- Which introduces a nonessential clause. HOWEVER, it can also be used to introduce the second essential clause in a sentence when that has already introduced the first essential clause.
Example: That is something which you will have to think about.
NOTE: You can often leave out which in the latter case to streamline the sentence.
In summary, when deciding which relative pronoun to use, that or which, consider whether or not the clause is needed (you can’t get rid of it for the sentence to be a full sentence) or unneeded (you can drop it and still have a sentence). If it is needed, that is the choice. If not, go with which.