Blast From the Past: "that" versus "which."

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Greetings and salutations, Fandom Grammar watchers!  Today, we’re going to cover the difference between two words that often confuse both writers and readers, which make the correct use of them difficult to master.  I’m talking, of course, about that and which (both of which were covered at length by katiefoolery in her article about the same subject).



But before we dive into the main course, we’ll devour two appetizers: the difference between demonstrative and interrogative pronouns, and the difference between restrictive and non-restrictive clauses.

The former is easy enough to remember: demonstrative pronouns demonstrate while interrogative pronouns interrogate.  That is, demonstrative pronouns include words that absolutely identify such as this, these, those, and our pal, that, and interrogative pronouns include words that ask questions, such as where, who, and what, and our other buddy, which.  They are known respectively as “Th”-word and “Wh”-words.

An example of demonstrative pronouns:

“Let’s divide it—so we both have something to protect ourselves with in case we get separated,” Leon said to Ada, nodding at the trunk full of weapons and ammunition boxes that they’d found.

 She nodded back.  “I’ll take that shotgun along with those three cases,” she said as she pointed at the Remington 12-gauge.

Under the Remington was a rifle—a Ruger K1—with a scope.  “My dad taught me how to use one of these when I was a kid,” he said.  He shouldered it, feeling its familiar weight, and moved the crosshairs over a lantern setting on a desk against the opposite wall.

“It looks like there’s only this one case of shells, though,” said Ada, as she held up a single blue box.

In this scenario, Leon and Ada are talking about specific objects, thereby absolutely identifying said objects with no possible reference to any other objects.  Therefore, they use demonstrative pronouns when referring to those specific objects.

And now an example of interrogative pronouns:

 “Which one should I take…” Claire was saying to herself as she looked down at the guns that she had laid out upon Chief Irons’s desk.  She picked up the big one with the fat nozzle—the “grenade launcher,” she’d called it—nodded to herself, and walked into the slid-open compartment that had been hidden behind the back wall.

“Wait, where are you going?” Sherry said, running after her.

Claire turned around and smiled.  “I’m just going to go down the elevator and have a look around.  I want to make sure it’s safe before you come down, sweetie.”

“So why are you taking that big gun?  Who do you think’s down there?”

Claire’s smile twitched.  “It’s not who I’m worried about so much as what.”

In this scenario, the inquisitive Sherry does not know of any specific entities or objects involved in the situation, so she uses the interrogative pronouns to refer to the possibility of their presence.  Likewise, Claire at first does not know which weapon she’ll choose, so she uses an interrogative pronoun to refer to the undetermined weapon until she has determined it.

Ultimately, the difference between demonstrative pronouns and interrogative pronouns lies in possibility.  If there are multiple identity possibilities for the noun that the pronoun is replacing, then use the appropriate interrogative pronoun; if there is only one identity possibility, use an appropriate demonstrative pronoun.

This leads us to the difference between restrictive and non-restrictive clauses.  Restrictive clauses are clauses attached to a noun that contain necessary information about that noun.  Non-restrictive clauses, on the other hand, are attached to a noun but contain no necessary information about it.  Because the restrictive clause shows necessary information but the non-restrictive does not, it makes sense that the restrict clause generally takes the demonstrative pronoun that while the non-restrictive pronoun takes the interrogative pronoun which.

Examples of the restrictive clause:

Alexia slipped the ring that held the Ashfords’ blue family gem off Alfred’s finger and placed it on her own.

Manuela twisted the snake bracelet that her father had given her for her birthday nervously around her wrist.

Chief Irons swiveled around in his chair and looked at the hawk that he’d stuffed himself.

Examples of the non-restrictive clause:

Alexia slipped the ring, which held the Ashfords’ blue family gem, off Alfred’s finger and placed it on her own.

Manuela twisted the snake bracelet, which her father had given her for her birthday, nervously around her wrist.

Chief Irons swiveled around in his chair and looked at the hawk, which he’d stuffed himself.

To make matters more complicated, however, there exist two sub-branches of restrictive clauses called the essential clause and the non-essential clause.  The essential clause operates exactly as a regular restrictive clause, demonstrating necessary information about a specific noun.  But what if the noun is grammatically specific but not factually specific?  The non-essential clause covers this particular situation, in which a specific noun is named but the circumstances surrounding that noun remain unknown and therefore open to possibilities.  Structurally, the non-essential clause works like a regular restrictive clause, except it takes which instead of that.

An example of the essential clause:

“Hunnigan, send me the intel on Simmons that you found earlier,” said Helena through the mouth piece.

And an example of the non-essential clause:

“Hunnigan, send me any intel on Simmons which you can find,” said Helena through the mouth piece.

In both cases, we have a grammatically specific noun, intel.  In the case of the essential clause, however, Helena is referring to factually specific (and therefore absolutely identified) intel, so she uses that. In the case of the non-essential clause, she is referring to any possible (and therefore not absolutely identified) intel, so she uses which. 

If you’re still having issues remembering the difference between that and which (and I assure you: you wouldn’t be the only one), just keep in mind that typically, clauses that begin with that usually aren’t sandwiched between commas while clauses that begin with which typically are.  The only exception to this rule is the case of a factually unspecific noun, which will most likely be proceeded by a factually unspecific adjective such as any or a/an.

Sources
IIT Chicago-Kent College of Law
Oxford Dictionaries
Regent University
The University of Calgary
The Web Environment @ the University of Michigan
Writer’s Digest