Answers to Questions About Restrictive and Nonrestrictive Constructions

By Mark Nichol

The following questions from readers pertain to how to distinguish essential information from nonessential information.

1. A colleague of mine wrote, “Institutions need to be able to collect and collate data in a centralized tool, which is easily accessible and can be mined to inform data-analytics activities.” I corrected it to “Institutions need to be able to collect and collate data in a centralized tool that is easily accessible and can be mined to inform data-analytics activities,” but she disagrees with the edit. I know I’m right, but how do I explain it to her?

In your revision, you have altered the sentence to reflect the writer’s interest in presenting the essential details that the centralized tool is easily accessible and is conducive to data mining. The original version of the sentence offers the details in an offhand fashion, set off as a subordinate clause rather than as part of the main clause. Both versions are grammatically valid, but only your revision conveys the emphasis the writer intends.

2. When is it right to put a comma in front of “such as”? In many of your examples, I notice that there is no specific standard to using “such as.” At times, you write it as “, such as,” and at other times, you omit the comma preceding “such as.” Are there any rules to using a comma before “such as”?

Precede “such as” with a comma when the phrase that includes the listed examples is not essential to the sentence, such as in “The program offers team sports, such as basketball and softball, for adults in recreational and competitive leagues.” Omit a comma before “such as” when the information is essential: “The program offers team sports such as the ones listed below for adults in both recreational and competitive leagues.”

The wording in these examples is identical, but there’s a subtle difference in meaning: The commas in the first example set off the phrase “such as basketball and softball” as a parenthesis in the main clause “The program offers team sports for adults in recreational and competitive leagues,” which states that the program is exclusively for adults. The second sentence refers to a list of sports for adults in recreational and competitive leagues, implying that other team sports may be offered that are exclusively for children or are for adults or children alike or are only recreational or only competitive.

3. “In the sentence ‘Chairs that don’t have cushions are uncomfortable to sit on,’ I think which is acceptable in place of that, because chairs is a nonperson noun. I would appreciate if you let me know why that is the only correct answer.”

The fact that chairs refers to a class of objects, rather than people, is irrelevant. That is not the only correct answer, but it is the best one.

In American English, most careful writers employ that and which distinctly to clarify the difference in meaning between restrictively and nonrestrictively constructed sentences:

“Chairs that don’t have cushions are uncomfortable to sit on” refers to a particular class of chairs: those without cushions. The implication is that many chairs are comfortable; the ones specifically referred to are a categorical exception.

“Chairs, which don’t have cushions, are uncomfortable to sit on” expresses—erroneously—that all chairs are cushionless. (The phrase “which don’t have cushions” is parenthetical; it can be omitted without altering the meaning of the basic sentence: “Chairs are uncomfortable to sit on.” However, this sentence is also incorrect in its assertion.)

Some writers will use which in both types of sentences: “Chairs which don’t have cushions are uncomfortable to sit on” — and this is common in British English — but most people (at least those in the United States) recognize that the distinctive wording helps strengthen the role of the commas in distinguishing meaning.

By the way, although “Chairs, which don’t have cushions, are uncomfortable to sit on” and the abridged version, “Chairs are uncomfortable to sit on,” are logically erroneous — comfortable chairs certainly do exist (though, unfortunately, I’m not sitting in one right now) — a similarly constructed sentence can be valid: “Ostriches, which can’t fly, rely on their strong legs for mobility.” Conversely, because no ostriches are capable of flight, “Ostriches that can’t fly rely on their strong legs for mobility” is problematic.

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1 Response to “Answers to Questions About Restrictive and Nonrestrictive Constructions”

  • Tim Slager

    Sometimes you knock out of the park, Mark. Well explained!

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