Critical, Think,ing: Part Tw,o

Guest Columnist
Sarah Pottenger

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Rule #5: The Restrictive/Nonrestrictive Rule

Use commas to set off nonrestrictive elements.

This one's a bit more complicated, so hang in there. Word groups describing nouns or pronouns (adjective clauses, adjective phrases, and appositives—don't worry, I'll explain each) are restrictive or nonrestrictive. A restrictive element defines or limits the meaning of the word it modifies and is therefore essential to the meaning of the sentence. Because it contains essential information, a restrictive element IS NOT set off with commas.

Restrictive: For camp Jessica needed clothes that were washable.

If you remove a restrictive element from a sentence, the meaning changes significantly, becoming more general than you intended (For camp Jessica needed clothes). I don't mean that Jessica needed clothes in general. The intended meaning is more limited: Jessica needed washable clothes.

A nonrestrictive element describes a noun or pronoun whose meaning has already been clearly defined or limited. Because it contains nonessential information, a nonrestrictive element IS set off with commas.

Nonrestrictive: For camp Luke needed sturdy shoes, which were expensive.

If you remove a nonrestrictive element from a sentence, the meaning doesn't change dramatically. Some meaning is lost, to be sure, but the defining characteristics of the person or thing described remain the same as before. Luke needed sturdy shoes, and those happened to be expensive.

*Adjective clauses are patterned like sentences, containing subjects and verbs, but they function within sentences as modifiers of nouns or pronouns. They always follow the word they modify, usually immediately. Adjective clauses begin with a relative pronoun (who, whom, whose, which, that) or with a relative adverb (where, when). Nonrestrictive adjective clauses are set off with commas; restrictive adjective clauses are not.

Nonrestrictive: Michelle's house, which is located on thirteen acres, was completely furnished with bats in the rafters and mice in the kitchen.

The clause which is located on thirteen acres does not restrict the meaning of Michelle's house, so the information is nonessential.

Restrictive: An office manager for a corporation that had government contracts asked her supervisor whether she could reprimand her co-workers for smoking.

Because the adjective clause that had government contracts identifies the corporation, the information is essential.

*Adjective phrases—specifically, prepositional or verbal phrases functioning as adjectives—may be restrictive or nonrestrictive. Nonrestrictive phrases are set off with commas; restrictive phrases are not.

Nonrestrictive: The spaceship, with its spotlight illuminating the area, hovered above.

The "with" phrase is nonessential because its purpose is not to specify which of two or more spaceships is being discussed.

Restrictive: One corner of the attic was filled with newspapers dating from the turn of the century.

Dating from the turn of the century restricts the meaning of newspapers, so there's no comma.

*Appositives are nouns or noun phrases that rename a nearby noun. Nonrestrictive appositives are set off with commas; restrictive appositives are not.

Nonrestrictive: Taylor's first novel, The Other Battlefield, was a best-seller.

The term first restricts the meaning to one novel, so the appositive The Other Battlefield is nonrestrictive.

Restrictive: The song “Stand My Ground” was blasted out of amplifiers ten feet tall.

Once they've read song, readers still don't know precisely which song the writer means. The appositive following song (“Stand My Ground”) restricts its meaning.

Rule #6: The Catch-all Rule

Use commas to set off transitional and parenthetical expressions, absolute phrases, and elements expressing contrast.

*Transitional expressions serve as bridges between sentences or parts of sentences. They include conjunctive adverbs such as however, therefore, and moreover and transitional phrases such as for example, as a matter of fact, and in other words. When a transitional expression appears between independent clauses in a compound sentence, it's preceded by a semi-colon and is usually followed by a comma (we'll talk about semi-colons in another article).

Example: Elizabeth did not understand our langauge; moreover, she was unfamiliar with our customs.

When a transitional expression appears at the beginning of a sentence or in the middle of an independent clause, it is usually set off with commas.

Example: As a matter of fact, Lainey's poems usually contain good concrete imagery.
Example: Flynn looked very promising as a candidate; he was busy, however, through the month of February.

Exception: If a transitional expression blends smoothly with the rest of the sentence, calling for little or no pause in reading, it doesn't need to be set off with a comma. Expressions such as also, at least, certainly, consequently, indeed, of course, moreover, no doubt, perhaps, then, and therefore don't always call for a pause.

Example: Anna's bicycle is broken; therefore you will need to borrow Julie's.

Note: The conjunctive adverb however always calls for a pause, but it shouldn't be confused with however meaning “no matter how,” which does not call for a pause.

Example: However hard Bree tried, she could not match her previous record.

*Parenthetical expressions should be set off with commas. Providing supplemental information, they interrupt the flow of a sentence or appear at the end as afterthoughts.

Example: Evolution, as far as we know, doesn't work this way.
Example: The accordion weighed forty pounds, give or take a few ounces.

*Absolute phrases, which modify the whole sentence, usually consist of a noun followed by a participle or participial phrase. Absolute phrases may appear at the beginning or at the end of a sentence. Wherever they appear, they should be set off with commas.

Example: Her tennis game at last perfected, Jaimee won the cup.
Example: Jordan was forced to rely on public transportation, his car having been wrecked the week before.

*Contrasted elements—sharp contrasts beginning with words such as not, never and unlike are set off with commas.

Example: Becca, unlike Brianna, had no loathing for dance contests.
Example: Mary talks to Mercy as an adult and friend, not as her little sister.

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Sarah Pottenger is a long-time mentor at the teen writer's forum The Clean Place, a five-time winner of NaNoWriMo, a sci fi fan and writer, and a hater of peas. This article first appeared on The Clean Place.