"Allow only the non-restrictive which," my professor wrote in one assignment's instructions, as if I knew what that meant. As if I understood the difference between a restrictive which and a non-restrictive one. Logically, the fact that she'd stated the rule at all meant that there would be examples of both which's used; this was an error that had been added intentionally to test my knowledge of the rule and my ability to apply it correctly. I began to twitch involuntarily.
However, I wasn't about to let this get me down. I'd been studying for months and had this grammar thing sorted. Which was only a word, after all---it wouldn't beat me. So, like any other studious fool desperate to cream her assignment, I pulled out my collection of usage guides and books on grammar. I went over to Grammar Girl and read what she had to say on the matter (always informative, Grammar Girl is) and gathered a vague understanding. I opened the assignment and began working. A droplet of determined sweat trickled over my brow.
And then this happened:
"There is a cluster of lymph nodes located under the arms which may contribute to the development of certain cancers."
There it was, the jerk. A pig-headed which boldly sat in the middle of the sentence seeming to chuckle at me. This which made perfect sense, didn't it? I ran for the tranquilizers and considered the use of my grammar guides as kindling.
How do you know if a which is restrictive or non? How do you know if it is more grammatically correct to use which over that in a situation like this?
Here's a secret: in actuality, you can use either. Neither one is officially incorrect. However, there are times when one might be more appropriate than the other; they do both have a function. Here's how to tell:
There are two fairly simple indicators that will help you decide. First, look at the which's surrounding punctuation. Is it preceded by a comma? Next, determine the importance of the information the which phrase gives. Is it imperative to the sentence's meaning?
A non-restrictive which phrase will be incapsulated in commas, and it will state a little frivolous fact that could be cut without hindering the core meaning of the sentence.
Here's an example:
"The car, which is a hideous shade of orange, is Dinglebert's."
If you were to remove the phrase "which is a hideous shade of orange," you would still have a perfectly acceptable sentence: "The car is Dinglebert's."
If we were to replace our non-restrictive which with a restrictive that, we'd give our sentence a different meaning:
"The car that is a hideous shade of orange is Dinglebert's."
With this example, the restrictive that tells us that there is more than one car, but only the hideous orange one is Dinglebert's.
So now, look back at the sentence from my assignment. How would you correct it? Is the which stuffed snugly between a cozy set of commas? Does it begin a phrase containing information that could be yanked without changing the meaning of the sentence?
If you guessed: "There is a cluster of lymph nodes located under the arms that may contribute to the development of certain cancers," you might be right.