Using the Em dash (long dash)
Em dashes — called this because they resemble the width of the character m — are used for emphasis or interruption. They can be used on their own or in pairs to offset a word or phrase. Note these examples:
Many people have trouble deciding on which diet to follow — one which emphasizes carb control and exercise or one which emphasize calorie control.
Many people have trouble choosing a life partner — one who is physically appealing or one whose values are appealing — because they have little sense of what makes a relationship work.
The double hyphen (--) is sometimes used instead of the em dash. This is often the case for people who do not know how to create an em dash using their word processing program. One should determine how to do this and not use the double hyphen as it looks amateurish.
Using the long dash, the em dash, is some what a personal choice but there are considerations to be made before using it. In the case of poetry, the decision to use the em dash is perhaps more important than in prose. Of course any formal writing ought to have fewer odd bits of punctuation than any informal writing. One thing that web writing has wrought is a casualness over issues of punctuation. This is a dangerous trap for serious literary writers of all genres. Avoiding dashes, semicolons, and ellipses is best unless the writer is adept at punctuation and has a specific purpose for using these somewhat renegade forms.
Here are some suggestions for considering whether or not to use the em dash in your writing:
1. Dashes are not to be used commonly. If your paper or poems have multiple dashes, make sure to check them over and see whether they were used correctly and appropriately or not. Dashes most definitely ought to be used SPARINGLY.
2. Rule of thumb: If you have a dash where a comma would work, use the comma, for pete's sake, use the comma!
3. If you use a dash toward the end of a sentence, do not put an ending dash right before the period. In poetry, do not use a dash before any other punctuation or just after any other punctuation. You may wish to end a line with the em dash, but if a comma will do, use the comma!
4. One should not replace commas being used for an appositive with dashes. Simply because it’s an interruption, doesn’t mean a dash belongs there. Emily Dickinson used dashes in most surprising ways; it became “her style” in a sense. Most of us do not use dashes to highlight a personal style. We use them because we are tentative about other punctuation. (NOTE: some poets use the ellipsis profusely for the same reason.)
5. Use dashes instead of parentheses when the note you are making is more connected to the initial sentence, as parentheses usually indicate a more separate or personal thought. Use dashes, instead of commas, when the note breaks up the flow of a sentence, as commas are typically used for an item that fits in more.
6. When using a dash in terms of explanations or listings, i.e. in a formal paper, it is recommended to rearrange the sentence so that a colon could be used instead. This is especially true in poetry. Dashes tend to interrupt the sentence (line), which is not the desired tone of a formal paper or formal verse. In poetry, the interruption is best done with white space or commas.
7. Most commonly, a dash connects an independent clause with another, with a separate or interrupting thought plus a conjunction like or, but, yet, as, for, and after the second dash.
8. The dash works somewhat like parentheses or commas, but it is used where stronger punctuation is needed. It is used to connect an independent clause with the 'interrupting' thought:
- Independent clause — thought — independent clause.
- Independent clause — thought.
9. Using dashes in poetry makes a visual difference for the reader. It is a “stopper” which makes the reader pause for a longer time than a comma or even a parenthesis. Ask ourself if you want the reader focused so hard on the phrase or material within the dashes that he/she stops to ponder that at the possible expense of the rest of the line or stanza.
For me, a long dash is a punctuation mark of last resort in most cases. I almost NEVER use them in pairs. I admit to a certain bias (see #9 above) and avoid the appearance of arbitrariness or lack of understanding of punctuation. When asked to explain this stance, I have to stop and think from a grammatical point of view just why. I am so used to avoidance of this piece of punctuation that it is as normal as breathing to me. But hopefully you will have gained a bit of insight here as I waded through serious explanations.