Parenthetical Phrases

By Mark Nichol

Let’s say, for the sake of argument, that you’re explaining something in writing — such as which punctuation marks to use to signal a break in thought — and you want to make it clear to your readers (many of whom may never have realized that there are distinctions to be made). How would you do it?

I just did.

One of three basic strategies usually suffices to set a parenthetical phrase off from its root sentence. By “parenthetical phrase,” I mean one that constitutes a digression (or a clarification) — and, despite the name, it doesn’t have to involve parentheses.

I did it again.

You see, the mildest form of parenthesis, for when you want to quickly insert a detail without distracting the reader, is a subordinate clause: a nonessential phrase framed by a pair of commas. The preceding sentence includes a subordinate clause: the one that begins “for when” and ends “the reader.” If you temporarily remove that phrase from the sentence, its structural integrity remains intact. (Try it; I’ll wait — but don’t forget to put it back when you’re done.) The subordinate-clause parenthesis is one strategy.

Another is to use the punctuation characters called parentheses. (The singular form, also used for the compositional device under discussion, is “parenthesis.”) Notice that I just inserted a parenthesis inside parentheses to make a point that isn’t key to the explanation but provides an additional dollop of information. Note also that I inserted a subordinate clause inside the parenthesis. That’s acceptable but shouldn’t be overdone, because it complicates sentence structure and can obfuscate writing.

The third device is the use of what are technically called em dashes — so called because they were originally the width of the letter “m” — though most people refer to them simply as dashes.

Digression: A pair of en dashes — the origin of this name should be apparent — are often used in place of em dashes, though they were appropriated from another use. Simple hyphens — either a single pair or two doubles — also appear in their place, especially online. Why? The hyphen is part of the ASCII roster of basic alphanumeric characters that automatically translate online, but em dashes and en dashes often have to be coded, or they’ll manifest in most browser windows as odd characters; we’ve all seen that error on even otherwise professional Web sites. Therefore, they’re used less often on the Internet. End of digression.

Dashes and their substitutes, as opposed to quotidian commas and wallflower parentheses, are best used to call attention to the inserted phrase — hey, look at me! — and note that often, they are used not in pairs with a parenthetical phrase within, but rather alone, setting a phrase off at the end of a sentence — a function commas but not parentheses share.

I have allowed these devices to proliferate here for the sake of instruction; but use them sparingly. (Especially, don’t use more than a single dash or a pair of dashes in one sentence or in consecutive sentences, or the passage may be difficult to follow.) Employed in moderation, and when each type is used according to its strength, parenthetical punctuation is a powerful textual tool — try it!

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13 Responses to “Parenthetical Phrases”

  • Kathryn

    An interesting and helpful analysis of something I tend to do without thinking about it–too often, in fact. Thanks.

  • Rebecca

    I use parenthetical phrases but now I’ll be more aware when I use them. I’ll take a step back and evaluate if it’s necessary.

  • John

    I was taught that an m-dash was not preceded or followed by a space. Most word processors are smart enough to convert the two n-dashes into an m-dash–but only if you don’t leave a space–reinforcing this particular notion.

    As usual, a useful and entertaining post. Thank you.

  • Deborah H

    I love dashes, especially the em dash. I noticed that you use a space before and after your dashes, which is contrary to how I was taught to use the dash—which was without spaces (way back in 1967, when I took my first typing class).

    Did the MLA change the rule? Am I hopelessly behind the times?

  • Ken

    @Meave,
    I noticed Mark put a space on both sides of a dash (as the AP Stylebook recommends in all cases except the start of a paragraph…). Printed books, however, don’t leave a space on both sides of a dash—why? I just did it.

  • Ken

    I meant “Maeve.” Sorry about my goof.

  • Mark Nichol

    Deborah and Ken:

    Many publications, including lots of Web sites, style em dashes with letter spaces preceding and following them because of the way text wraps, or transitions from one line to the next. If I were to omit letter spaces, a series of characters consisting of a word followed by an em dash followed by a word might be too long to fit at the end of a line.

    Because no letter spaces exist in this series, the entire series would break to the next line, which could form an unseemly dent in the margin.

    The style of margin this Web site uses — as do many others (and some print publications) — is called ragged right. In this style, each line ends randomly at the last word or punctuation mark that fits. Compare this style with a justified margin, the kind you see in many print publications, where each line is kerned, or spaced, to extend to a given width so that the right margin is aligned all up and down the page (or screen).

    That’s why em dashes are often styled without preceding and following letter spaces; the word-dash-word series won’t affect the margin. And Deborah, that’s why typing instruction specifies closed spaces around em dashes.

    I actually prefer the closed style, but in the case of ragged-right margins, I align with the open style.

  • Mark Nichol

    John:

    Yes, omission of letter spaces around an em dash is fine for word processing, but publication editors need to make a conscious decision about how to style dashes according to margin style and other aesthetic considerations.

    Because my work has often involved editing in design programs like InDesign and QuarkXpress, I’m accustomed to typing an em dash: On a Mac (the computer of choice in most publishing environments), the key command is shift+option+hyphen. On a PC, it’s Alt+0151.

  • Ken

    Thank you, Mark, for the explanation.

  • B. Rambo

    This is from Lewis Thomas’ delightful discussion of punctuation:

    There are no precise rules about punctuation (Fowler lays out some general advice (as best he can under the complex circumstances of English prose (he points out, for example, that we possess only four stops (the comma, the semicolon, the colon and the period (the question mark and exclamation point are not, strictly speaking, stops; they are indicators of tone (oddly enough, the Greeks employed the semicolon for their question mark (it produces a strange sensation to read a Greek sentence which is a straightforward question: Why weepest thou; (instead of Why weepest thou? (and, of course, there are parentheses (which are surely a kind of punctuation making this whole matter much more complicated by having to count up the left-handed parentheses in order to be sure of closing with the right number (but if the parentheses were left out, with nothing to work with but the stops we would have considerably more flexibility in the deploying of layers of meaning than if we tried to separate all the clauses by physical barriers (and in the latter case, while we might have more precision and exactitude for our meaning, we would lose the essential flavor of language, which is its wonderful ambiguity )))))))))))).

    http://www-personal.umich.edu/~jlawler/punctuation.html

  • Peter

    Printed books, however, don’t leave a space on both sides of a dash—why?

    Depends on the choice of font. In standard English-language usage, normal intertextual em-dashes should have a hair-space between the dash and the text. Some fonts have dashes with space around them, so you can just set them closed up; others don’t, and the typesetter has to insert hairspaces to avoid them touching surrounding letters. Occasionally, there’s call for a completely unspaced em rule…good fonts that have spaces in their em-dash also have an unspaced variant. But fully spaced em rules (i.e., with full interword spaces) are common in other languages. (And nowadays you see a lot of “printed books” that have never seen a typesetter…printed directly out of a word processor, etc.)

  • Pavel Axentiev

    If a parenthetical phrase begins a subordinate sentence, immediately following “that,” does there need to be a comma after “that”?

  • Pavel Axentiev

    For example:

    Notably, the authors concluded that, compared with phenytoin and ethosuximide, CBD was “the most efficacious of the drugs tested against limbic [after-discharges] and convulsions.”

    or

    Notably, the authors concluded that compared with phenytoin and ethosuximide, CBD was “the most efficacious of the drugs tested against limbic [after-discharges] and convulsions.”

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