Use the em dash for emphasis

The em dash has become the punctuation writers now fear, because it's one of AI's fingerprints. But it's a legitimate — and powerful — tool, and the fix isn't to avoid it; it's to use it well. Syntactically it does one thing: it marks a break and resumption in a sentence, letting you inject a thought whose grammar doesn't have to match the main clause. That's why expert writers reach for it to slip in examples, to make an aside, or to hedge against an objection without stopping the flow.

How it works

Syntax is only the mechanics; the power is in the semantics — what the dash means. And what a pair of em dashes means is emphasis. Reserve them for the clause you most want the reader to feel — a way to stress something without reaching for bold or italics. The force is comparative, so it depends on restraint: use dashes everywhere, the way careless writers overuse "however," and each one means less. Match the mark to the weight — a definition wants the quiet, subordinate "comma + which" ("the hikikomori, which refers to…"); an unobtrusive aside wants parentheses, gentler than a comma; and the em dash, loud and foregrounded, is for the thing you want to land hard.

Why it matters

Punctuation is a volume knob, and the em dash is turned up. Spend it on trivia — definitions, throwaway asides, every third sentence — and you've no way left to signal what actually matters, and the prose reads as breathless. Reserve it, and a single dash tells the reader this is the part to feel, doing the work of bold or italics without the shout. The writers who dash indiscriminately, even sharp ones, lose exactly this rhetorical force.

Try it

1. Count the em dashes on the page. If they're everywhere, most are stealing force from the one that should carry it.
2. Demote the weak ones: definitions to "comma + which," quiet asides to parentheses.
3. Keep the dash for the clause you'd otherwise bold — the point you want the reader to hit hardest.

Common pitfalls

Using the em dash to define a term — grammatically fine, rhetorically weak, because a definition belongs in a subordinate slot, not a spotlight. And beware the opposite fear: stripping every dash to avoid looking like AI, which just trades a strong tool for comma splices and clunky breaks.

A pair of em dashes should be reserved for emphasising the clauses you think most important — without using bold or italics — and not just for defining terms.

WILLIAM · THE EM DASH, EXPLAINED · 2026

The em dash is a spotlight. Point it at one thing, or it lights up nothing.

Drawn from

• William, The Em Dash, Explained (Writer Science, 2026).
• Related: Put the idea where the reader expects it, Break the rule on purpose, Out-human the machine.