The Difference Between Restrictive And Nonrestrictive Clauses

By Author: Jimmy Anderson
Total Articles: 41
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Certain books on grammar describe restrictive and nonrestrictive clauses as "necessary" or "unnecessary" clauses, and neither should be confused with "dependent" or "independent" clauses, which are also sometimes referred to as "main" or "subordinate" clauses.
To the latter, take this sentence: "I can see the birds in the distance because I have excellent vision." "I can see the birds in the distance," is an independent clause, as it is a self-contained sentence that can stand by itself. However, "because I have excellent vision," is not able to stand by itself as a sentence, and it is called an "dependent" clause, as it depends on something else to make it part of a complete sentence.
Dependent and Independent Clauses
Here's where it gets even more confusing, as there is really no direct relationship between the two sets of clauses, as commas don't always have to be used to separate dependent and independent clauses, yet they are mandatory to distinguish between restrictive and nonrestrictive clauses. Then to really compound the issue, it's the nonrestrictive (unnecessary) clauses that require commas and ...
... not the restrictive (necessary) clauses.
It's Good to Remember What Constitutes a Clause
To begin to weave through all of this, I've found it best to break it down in the simplest terms. And this begins with the definition of a "clause," which is a group of words with both a subject and a predicate.
Once we know this, in a sentence with multiple clauses, we have to ask if the one following the sentence's lead clause is necessary to the meaning of the sentence. Here are two examples: My brother, who gets all A's, is the star of the basketball team. Or: My brother who was a star player at his other school never made the team at his new one.
It's All a Matter of Degree
In the first sentence, the brother's academics don't have any relevance to his making the team, and for this reason, the clause "who gets all A's" would be set off with commas. Conversely, the brother's being a star player at one school and being cut at the other is quite pertinent to the message, and consequently the clause doesn't require commas.
However, It's Not Always Cut and Dried
And this is the rub, as scholars have long debated clause relevancy in circumstances pertaining to an author's intent, as few decisions are as easy as the examples provided via my basketball player. So while I opened this article with the remark that all nonrestrictive clauses must receive commas, there is discretion regarding the designation of restrictive and nonrestrictive material. But the author can make the distinction and let others argue its validity, and for clauses that are clearly subjective, I'm of the opinion that it would be impossible to effectively disregard the writer's decision.
The Long Sentence Can Present Another Problem
Long sentences containing restrictive clauses can be very hard to read, since to be grammatically correct they will not contain commas separating the clauses. I don't remember in which Fitzgerald story I read the sentence, but he wrote one long sentence that I had to read over and over to figure out the way it should've been punctuated. After the third of fourth time through it, I determined that he believed the long clause was necessary to his sentence's meaning; hence, no commas.
I had to parse this sentence, as it was part of a project I was working on, but nonacademic readers of course won't routinely do this. Frankly, if it wasn't a requirement I would've thought the sentence was lacking punctuation and moved on. When text gets this cumbersome, my opinion is to revise the sentence. I'd hardly have advised Mr. Fitzgerald to take another stab at this particular patch of rhetoric, but most of the rest of us aren't quite as his level; so, in this sort of situation, I believe it's a good idea to consider a different sentence structure all the way around.

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