That and which are relative pronouns that function similarly within a modifying clause, but are used differently within sentences. That is used as a relative pronoun for essential and nonessential clauses, but which is only used for nonessential clauses.
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The confusion between that and which lies in their use as pronouns for a modifying relative clause. In a sense, we use these terms to shout out, “look here!” and to make our points more clear. But in reality, that and which are used very differently from one another and are not as synonymous as people think.
The words that and which have several functions in the English Language, whether it’s for adjectives, pronouns, conjunctions, or adverbs. That and which are most commonly used as relative pronouns to introduce restrictive clauses, and which is additionally used as a pronoun to introduce nonrestrictive clauses.
Stated more simply, people confuse that and which because they look similar in sentence structure, and they are each used to provide extra information. For example,
I bought my dad a grammar book that I know he will love.
I bought my dad a grammar book, which I know he will love.
The two examples above look similar in structure, and they convey the same information, but are they really the same? A grammar expert would say no. The first sentence shown is what grammarians call a restrictive clause. But with the use of which in the middle of the sentence, the second sentence is transformed from a restrictive clause to a nonrestrictive, or nonessential clause.
What about who vs. which vs. that?
There’s one other type of confusing pronoun usage involving which vs. that: personal pronouns. While many people use that or which as a personal pronoun, it is considered improper to use them as such. When it comes to referencing people in a sentence, it’s better to use the word who because it’s more clear to use which and that in reference to objects, places, or ideas rather than people.
Beginner’s vocabulary for that vs. which
If you’re confused about what terms like modifying clause or restrictive clause mean, there’s no reason to worry. English grammar is notoriously difficult because of how different it’s taught in academia over time, or how it’s used within media style guides and regional dialects. And to be frank, the grammarian jargon involving which and that can make learning about their differences even more confusing.
Let’s take a look key vocabulary terms to help navigate the correct usage between that vs. which as pronouns:
Pronoun: A word that replaces a noun in a sentence after the subject noun is properly introduced (e.g., I, they, them, she, her, he, his).
Predicate: The section of a sentence using a verb to convey information about the sentence subject (e.g., “ran away” from the dog ran away).
Clause: Part of the sentence consisting of a predicate, verb, and sentence subject (e.g., The dog ran away from home).
Phrase: the smaller group of words in a sentence that provides the most meaning but does not exist as a full sentence in itself (e.g., the working woman, maybe later).
Conjunction: The connecting word between sentences, clauses, and words within the same clause (e.g., if, while, because, how).
Grammar rules for that vs. which
Now that we have introductory vocabulary out of the way, it’s important to learn the fundamental grammar rules for using that and which as pronouns:
That vs. which within relative clauses
There are four types of clauses that are used to structure sentences, which include independent/main grammatically, dependent/subordinate, noun, and then finally, relative/adjective. The main or independent clause always contains a subject and a verb to form a complete sentence. For example,
Kittens (subject) + love to play (verb)
The subordinate or dependent clause always contains subordinate conjunctions like because, even, if, or since. We create a subordinate clause to form a complete sentence, but the clause in itself is not a complete thought. For example,
Because (conjunction) + kittens (subject) + love to play (verb)
In the case of which vs. that, we use either term for relative clauses within the following structures:
Which/that + subject + verb, or
which/that (as subject substitute) + verb
That and which are found within relative clauses because they are relative pronouns. Other examples of relative pronouns include who, whom, whomever, whose, or whichever. However, it’s crucial to remember a rule of thumb for relative pronouns: that and which are not proper pronouns for people.
That vs. which in restrictive and nonrestrictive clauses
The next step to understanding the difference between that and which is to learn how they function while introducing modifying clauses via restrictive and nonrestrictive or non-defining clauses. A modifying clause always uses that or which after a noun in a sentence. For example,
She adopted a dogthat I adore.
We’re late because of our dog, which is fine because he’s adorable.
The key difference is that restrictive clauses contain essential information for the sentence to make sense, while nonrestrictive clauses present additional nonessential information. One way to immediately spot restrictive and nonrestrictive clauses is to check for commas since a restrictive clause has none.
Using the two example sentences above, can you tell which sentence is restrictive or nonrestrictive? The first example sentence is a restrictive clause because the relative pronoun directly modifies the subject, the dog, but it doesn’t require a comma within the sentence.
The second example sentence is a nonrestrictive clause because it contains a relative pronoun after the subject without modification, it requires the use of commas, and the extra information following the pronoun isn’t essential for primary meaning (i.e., We’re late because of our dog).
Which vs. that: the other pronouns
There are ultimately two ways to use that and which as pronouns and this is why we can use each term so differently within English grammar:
That’s, that, and those
Outside of formal sentence, that is used as a pronoun to indicate a person, place, or thing, and is often used as that’s, for “that is” or those when plural. That can be anything, whether you’re referencing time, an event, or an action, but that is always something specific and unique to the sentence it’s used for.
That is my closet.
That’s my jacket.
Those are my clothes.
After that, you’ll find my shoe rack.
Those are clothing hangers, and these are wall hooks.
In the case of using that as a pronoun to informally reference a person, we might hear somebody say,
You know that guy from class, who always talks too much?
That’s who I was talking about!
While it’s common to casually use that as an indirect pronoun in reference to another person, we wouldn’t want to use this form of that within formal writing. Neither example sentence is complete on its own, but in dialogue, there’s more context to who someone is referencing.
It’s also common to use that for idioms like all that to represent everything the sentence is implying or at that to introduce something additional or as an argumentative response.
She thinks she’s allthat and a bag of chips.
I can’t focus with allthat noise you make.
I had a long class and a boring one at that.
The student was a bad test taker, but they wrote beautiful essays at that.
Finally, we encounter the second use of which: the interrogative pronoun. We use which as an interrogative pronoun to narrow down a sentence object from a larger group of objects. For example,
Which pair of shoes do you like more?
Which ice cream is your favorite?
I’m not sure which table we reserved
How to use which and that for media style guides
One of the last frontiers for navigating that vs. which is learning about style rules within major academic and news media publications. The three most common style guides used by professional editors and writers include:
The Chicago Manual of Style (CMOS)
Associated Press Stylebook (AP Stylebook)
American Psychological Association Publication Manual (APA Style)
In regards to which vs. that, APA and CMOS both use that for restrictive clauses and which for nonrestrictive clauses. The AP Stylebook, however, advises against using that altogether unless it’s used for essential restrictive clauses. What this means is that AP Style omits the use of that unless removing the clause eliminates the meaning of the sentence.
If we dig through a recent AP Newsstory, we can see how the organization and style guide uses which and that in the following sentences:
“…she announced Friday night that she’d raised $1 million…”
“…argument that mayors have a better…”
“…has reached top-tier status in the state, which votes on…”
“…in the Republican-controlled Senate, which ‘may deepen our sense…’”
It’s notable how, in comparison to the use of that, which is used far less throughout the news story. There’s a likely explanation for this: which is easily replaced with other conjunctions like where, while, and as.
The danger of using that and which too frequently
Since writing is an art and art is subjective, it’s difficult to state what distinguishes good writing vs. bad writing definitively. But in terms of learning concise writing, it’s important to know how certain words hold the best writers back from delivering their message more clearly.
There are times when writers use that and which too much, and the meaning of the sentence becomes diluted with additional words. Academic writers often use that, which, or even “that in which,” to add as much information as they can at once, but it’s important to recognize when they are used with purpose and when they’re used to masquerade intellectual prose. The words that and which themselves don’t describe meaning in themselves, and they are only used as tools to present the sentence’s meaning altogether.
In this case, that and which tend to indicate run-on sentences or “Engfish,” a habit of writing taught to high students to incorporate as many fancy words as possible to fulfill a word quota. Examples of Engfish often display that or which, but what we find is how neither clause makes the sentence more clear or direct–– they simply exist to fill up the sentence.
See how well you understand the difference between which and that with the following multiple-choice questions.
True or false: in a nonrestrictive clause, “which” is preceded by a comma. a. True b. False
True or false: “that” is used for essential and nonessential clauses. a. True b. False
Which of the following sentences contain an essential clause? a. My sweater is blue, which is my favorite color. b. She’s always late to work, which is why she was fired. c. I saw a movie that I love. d. All of the above.
Which of the following sentences contain a nonessential clause? a. My sweater is blue, which is my favorite color. b. She’s always late to work, which is why she was fired. c. I saw a movie that I love. d. A and B
Cinema broke the fourth wall in ways _________ weren’t pleasing, but creepy and invasive, _________ made the audience uncomfortable. a. That, that b. Which, that c. That, which d. Which, which
“Engfish.” UCSB Writing Program, University of California, Santa Barbara, n.d.
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Alanna Madden is a freelance writer and editor from Portland, Oregon. Alanna specializes in data and news reporting and enjoys writing about art, culture, and STEM-related topics. I can be found on Linkedin.