Posted by: Jack Henry | June 25, 2018

Editor’s Corner: Commas, Parentheses, or Em Dashes?

Parenthetical phrases (also called parentheticals) provide nonessential information, such as examples, clarifications, or asides.

Parentheticals can be set off with commas, parentheses, or em dashes (—). How do you decide which punctuation to use?

Sometimes, there are readability considerations. If the parenthetical phrase already contains commas, it can be confusing to add more commas to the mix. In the following example, the second sentence is easier to understand than the first:

· “The Marx Brothers, Groucho, Harpo, and Chico, made 13 films.”

· “The Marx Brothers (Groucho, Harpo, and Chico) made 13 films.”

In many cases, the decision is purely stylistic. Commas are least noticeable, em dashes are very dramatic, and parentheses are somewhere in between. The following explanations and examples are from The Chicago Manual of Style:

If only a slight break is intended, commas may be used to set off a parenthetical element inserted into a sentence as an explanation or comment.

· “All the test participants, in spite of our initial fears, recovered.”

· “The Hooligan Report was, to say the least, a bombshell.”

Parentheses are stronger than a comma and similar to the dash. Like dashes but unlike commas, parentheses can set off text that has no grammatical relationship to the rest of the sentence.

· “He suspected that the noble gases (helium, neon, etc.) could produce a similar effect.”

· “Intelligence tests (e.g., the Stanford-Binet) are no longer widely used.”

· “Our final sample (collected under difficult conditions) contained an impurity.”

Em dashes can function as an alternative to parentheses, especially when an abrupt break in thought or sentence structure is called for.

· “The influence of three impressionists—Monet, Sisley, and Degas—is obvious in her work.”

· “The chancellor—he had been awake half the night—came down in an angry mood.”

· “My friends—that is, my former friends—ganged up on me.”

Tip: Don’t use spaces before or after an em dash.

Ben Ritter | Technical Editor | Symitar®
8985 Balboa Avenue | San Diego, CA 92123
619-682-3391 | or ext. 763391 |

Symitar Documentation Services

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  1. […] my previous post about parenthetical phrases, I talked about commas, parentheses, and em dashes. This week, I’ll discuss the once-common […]

  2. […] and one at the end to indicate the end of the pause. (You may remember a discussion about using parentheses and em dashes in a similar way. Just remember, this use is for nonessential […]

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