Dashes or Rules in Academic and Scientific Writing

Dashes or Rules: Using En and Em Dashes Effectively in Academic Writing

Dashes—whether en or em—play a subtle but powerful role in academic and scientific prose. They help writers signal sharp turns in thought, highlight parenthetical information, introduce afterthoughts, and provide emphasis in ways that commas, parentheses, or colons cannot quite achieve. For this reason, dashes appear in articles, theses, field reports, lectures, and even formal correspondence. But because they are inherently more expressive and less conventional than other punctuation marks, they must be used with precision and restraint.

Unlike commas, semicolons, or periods—each of which follows widely standardised rules—dashes differ in form, spacing, stylistic effect, and conventions across disciplines. Humanities writers often use them liberally to shape voice, while scientific writers tend to use them sparingly. Some journals encourage the em dash for clarity, while others prohibit dashes altogether except in tables. Understanding how and when to use dashes in academic prose ensures that your writing remains clear, professional, and stylistically consistent.

1) What are dashes, and why do they matter?

In typography, two horizontal marks are commonly used as dashes: the en dash (–) and the em dash (—). Their names come from traditional printing widths: an en dash is roughly the width of the letter “n,” an em dash roughly the width of “m.” Although they may look similar at a glance, their functions differ.

Academic writers encounter dashes in two primary contexts:

• parenthetical or interruptive clauses, where the dash signals a break stronger than commas
• explanatory or summarising clauses at the end of a sentence, functioning like a more relaxed colon

Because dashes carry rhetorical weight, they help writers craft sentences that mirror the rhythm of thought. A dash forces a momentary pause—longer than a comma, shorter than a full stop—and in doing so, highlights what follows or what lies between the dashes. When used well, this enhances clarity and emphasis. When used too often, it becomes distracting.

2) Using dashes for mid-sentence parenthetical clauses

The most recognisable use of dashes is to enclose a parenthetical clause in the middle of a sentence. This construction signals an interruption in the main syntactic flow. Unlike parentheses—which tuck information away—or commas—which may not always convey sufficient emphasis—the dash gives the aside a deliberate, attention-worthy presence.

Example:

Here, the clause “a big black one!” provides clarifying detail that interrupts the main statement. The paired dashes (one before and one after) indicate that the interruption begins and ends. This structure works in academic prose as well:

Because parenthetical dashes create a stronger break than commas, they are ideal when the interruptive information is important but not syntactically central. They help prevent ambiguity, maintain sentence rhythm, and highlight a detail without forcing it into the primary clause structure.

3) Using a single dash at the end of a sentence

When an explanatory or clarifying clause appears at the end of a sentence, only one dash is used. In this construction, the dash functions similarly to a colon: it introduces examples, elaborations, or conclusions.

Examples:

In both examples, the dash prepares the reader for additional information that completes or sharpens the idea. This usage is common in academic prose when highlighting results, introducing lists, or specifying implications:

The key principle is structural clarity: a single dash is used only when the parenthetical element appears at the end and does not interrupt the main syntactic line of the sentence.

4) What punctuation can (and cannot) appear near dashes?

Many writers inadvertently add punctuation before or after dashes in ways that break formal style conventions. The rules are straightforward:

• No punctuation should appear before an opening dash introducing a parenthetical clause.
• A closing dash can be preceded by ? or ! if they belong to the parenthetical material.
• A closing dash should not be preceded by a comma, semicolon, colon, or period.

Thus, the following is correct:

But these are incorrect:

• *The third dataset, – surprisingly large – confirmed the earlier trend.
• *The third dataset: – surprisingly large – confirmed the earlier trend.

Internal punctuation inside the parenthetical clause is fine (“surprisingly large!”), but external punctuation should not collide with the dash.

5) En dashes vs. em dashes: form and spacing

In running academic text, writers must choose whether to use spaced en dashes or closed em dashes for parenthetical clauses. Never combine the two systems in the same document. Consistency matters more than the choice itself.

a) En dash style (spaced)

This is common in British and international publishing. The spaces make the break feel slightly lighter and visually open.

b) Em dash style (closed)

This is the standard in American academic publishing and many scientific journals. Because the em dash is longer, no spaces are used.

Whichever option you choose, apply it consistently across chapters, sections, tables, captions, and references. Switching arbitrarily makes the text appear unedited.

6) Why dashes feel less formal than other punctuation

Dashes have a conversational tone because they mimic the rhythm of spoken language: pauses, afterthoughts, shifts, and emphasised clarifications. This quality makes them excellent for readable academic writing but problematic when overused. Excessive dashes can make formal prose sound emotional or inconsistent in tone.

Consider the alternatives:

• Commas integrate information smoothly without drawing attention.
• Parentheses quieten the information, signalling that it is optional.
• Colons formally introduce explanations or lists.
• Dashes emphasise, interrupt, draw attention, or dramatise.

Because dashes stand out visually and rhetorically, using them in every sentence would undermine the neutrality expected in scholarly exposition. Best practice is to use no more than one dash-marked clause per sentence unless replicating a specific stylistic effect.

7) When dashes should not be used

Although versatile, dashes are not suitable for every syntactic or rhetorical purpose. Avoid using dashes when:

• the relationship between clauses is logical rather than interruptive (use a colon or semicolon instead)
• the parenthetical information is minor or optional (use parentheses)
• the clause is essential to sentence meaning (integrate it with commas or restructure)
• your target journal prohibits or discourages dashes (common in certain sciences)

Dashes must never replace disciplined sentence structure. If you find yourself using dashes to fix unclear sentences, rewrite the sentence instead.

8) Using dashes for emphasis in academic writing

When used sparingly, dashes can highlight a surprising result, underscore a contrast, or mark a pivot in argument. Examples:

or:

Here the dash adds rhetorical force, but the sentence remains structurally sound. Reserve this technique for moments where emphasis is truly beneficial.

9) Dashes in lists, enumerations, and definitions

Dashes can clarify list structures when colons feel too formal or when the list completes the thought organically. For example:

This is acceptable in narrative prose, though formal methodologies usually prefer colons or itemised lists.

Dashes are also effective in glosses or in-line definitions:

10) Revising sentences that use dashes

A helpful method for editing is to remove each dash-marked clause temporarily. If the sentence still works structurally and logically, the dash likely serves a stylistic—not grammatical—role. If the sentence collapses, the dash is doing structural work that might be better handled by a different punctuation mark or by rewriting.

When proofreading, watch for three common problems:

• Overuse: frequent dashes weaken their impact.
• Confusion: mixing en and em dashes.
• Collision: misused punctuation near dashes.

A disciplined revision process ensures that each dash contributes meaningfully to clarity and flow.

Conclusion

Dashes are versatile punctuation marks that offer expressive power when used with restraint. They shape rhythm, provide emphasis, and highlight parenthetical ideas more assertively than commas or parentheses. To use them effectively in scholarly writing, choose between en and em dash styles, apply punctuation rules carefully, avoid cluttering sentences with multiple dash-set clauses, and rely on them only when they genuinely enhance clarity. Treat dashes as specialised rhetorical tools: subtle, strategic, and always deliberate.