October 17, 2019 Feature

A Once Rogue Punctuation Mark Gains Respectability: What You Can Now Accomplish with an Em Dash

A look at how the em dash has been used, and three useful things we can now do with it.

George D. Gopen

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An em dash — a double-length hyphen, taking up as much width as the letter M — was once considered as shameful a sin in formal discourse as slang or contractions. When I was attending the once-and-still-wondrous Roxbury Latin School (founded in 1645), some 60 years ago, had I used this hyper-hyphen punctuation mark (see the previous sentence for an example of a pair of them at work), I would have been sent straightaway to the headmaster’s office to be reprimanded for my act of moral turpitude. I might as well have slapped the English master in the face. All that has changed now; but it took a good long time to change. This On the Papers essay explains both how it happened and what excellent use you can make of this new best punctuational friend.

(Historical note: The worst four-letter word my classmates and I could ever have used in a writing assignment was “ain’t,” it being both slang and a contraction.)

The em dash has been nurtured in formal prose for a long enough time that we can now announce rules for its usage. While many grammarians love rules for the sake of order, and have their red pens always at the ready to quell disorder, I rejoice when a new arrival like the em dash gives writers better ways to send interpretive signals to their readers.

Successful new rules for writing come about in much the same way as successful legislation happens. We have long learned that it often does not work well to formulate legislation in order to change people’s behavior. The most glaring example is our 14-year experiment with Prohibition. No, laws work better when they simply articulate and codify what public behavior has already become. Enough traffic accidents at a given intersection may lead to the insertion of a new traffic light.

The em dash started to creep into use, to my memory, in the late 1960s, that era when all sorts of disregard for authority became matters of public behavior. Fiction writers were allowed to get away with them, especially in passages of dialogue, as they looked to approximate stylistic reality. Journalists found good reasons to include them. Without anyone particularly noticing it, form followed function: As certain things became useful, they slowly assumed a rightful place in writing. When grammar books started taking note (and you can check this out on the internet’s definitions of the em dash even today), the newfound usage was merely considered a victory for informality over formality. Actually, it has become far more than that.

Haydn, Mozart, and Beethoven all used the same kind of progression of materials in their music when writing many of the brisk, major movements in symphonies and sonatas. They had no name for it: It just worked well for them. Years later, composers and musicologists gave that form a name — sonata allegro form — and disquisissed at length about its rules. It is now time for us to look back at how the em dash has been used and articulate the three helpful things we can now do with it.


The first concerns the formation of lists. We used to have an extraordinarily baroque punctuation rule for lists: Introduce your formal list with a colon; then separate the list members from each other by commas UNLESS one of the members itself has an internal comma, IN WHICH CASE you then separate the members by semicolons. (Whew!) We no longer need this, because we now have two completely separate ways of constructing lists.

If the list’s members each need to be allowed a certain amount of weight and emphasis, introduce the list with a colon and separate the members with semicolons. Both of those marks of punctuation (I call the structural location to which they give closure “stress positions”) invite the reader to give a separate moment of attention and value to each list member.

In order to go forward with this purchase, we must prepare ourselves by accomplishing three pre-tasks: a thorough inventory of both inventories; a securing of the cooperation of both of the adjoining landowners; and an investigation into the history of the two outstanding lawsuits.

Each of the tasks, each with its own stress position, has a moment to reverberate in the reader’s mind. Now reread the paragraph, changing in your mind’s eye the semicolons to commas. Can you see how burdensome it has become?

But if your list is a lightweight list, one that can be read in a single, slight, continuous breath, you can now introduce such a list by an em dash and separate its members by commas. You ask your car salesperson in what colors he can get you a Model 174b before the first of next month. He sends you an email:

I can get you the 174b by that date in three colors — red, white, and blue.

“Red, white, and blue” can roll off the mind’s tongue in one swift motion. Your salesman would have proved pompous and ridiculous had he written you,

I can get you the 174b by that date in three colors: red; white; and blue.

Too much heavy artillery for the job at hand.

Sentence Interruption

The second use of the em dash involves a pair of them interrupting a sentence in a manner similar to but different from the interruption caused by a set of parentheses. Again we have gained something. Compare the two interrupters:

We can expect cooperation from all of the tenants (except the Harringtons) by the first of the month.

We can expect cooperation from all of the tenants — except the Harringtons — by the first of the month.

This is not a question of which is right or superior or preferable: It is a question of how the two differ from each other. The parenthetical interruption invites the reader to lower the silent reading voice, thus rendering the parenthetical contents of relatively little importance: “Sure, the Harringtons might not get it together to sign the agreement; but we don’t really need them.” The em dashes, on the other hand, invite the reader to raise that silent voice: “Darn it, those Harringtons may prove the fly in this ointment. We will have to do something about that.”

This approaches the kind of control a musical composer has with signs that tell the performer to suddenly, and briefly, get either louder or softer. Em dashes offer a subtle but convincing reading instruction that goes in the other direction from that offered by parentheses.

Sentence Endings

The third gift the em dash has for us occurs when a single dash appears just before the end of a sentence. Well used, it is once again subtle and once again effective. It concerns an important reader expectation I have revisited many times in this series of essays — the stress position. Readers naturally tend to stress any material that arrives just as the grammatical structure of the sentence comes to a full halt. That halt occurs at the arrival of any properly used period, colon, or semicolon. (It can never occur at a comma.) As we sense a sentence is winding toward its end, our expectation increases that we shall be emphasizing there the most stress-worthy material in the sentence. Our failure as writers in English to put the stress-worthy material in the stress position remains the number one problem in legal writing, everywhere.

If, as readers, we approach the end of the sentence and spot an em dash at the sentence’s penultimate moment, it says all of the following to us: “Dear reader, if I had been a period instead of an em dash, this would have been a perfectly fine sentence. The material coming just before me was completely capable of being the most important thing for you to consider in this sentence. But, dear reader, my message to you is that we have one yet even more important thing to say, which will come immediately after me, in the stress position. It will one-up the previous important bit of information. Be prepared for it.”

We have been able to get signed permission forms from everyone in both buildings — except those cursed Harringtons.

After all this good news about the em dash, I must end with a great em dash annoyance, perpetrated upon us by a grand majority of reader-insensitive writers of grammar books. We are told we must use no space to the left or right of an em dash. What? Doing that connects the material surrounding the dashes to the dashes; but the whole purpose of the dash is to separate material. I wish to thank my understanding editors who have allowed me — even if just for this essay — to let my dashes breathe by putting space around them, violating usual ABA style. If a large number of us continually make such requests of editors, we may yet be able to foment a reader-friendly punctuational revolution.

Which reminds me of the nonsensical fracas over the Oxford comma — but I’ve covered that in a previous essay.

George D. Gopen

The author is Professor Emeritus of the Practice of Rhetoric at Duke University.

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