Oh sweet, we can use em dashes again.
Peter Gostev
@petergostev
Sep 25
RIP em dash

Sep 25, 2026 · 10:29 PM UTC

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Replying to @conorsen
I'm in the job market right now, and 5.5 is WAY better than 5 on producing good copy
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I’ll never use 5 again.
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Replying to @conorsen
some of us never stopped
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Replying to @conorsen
Thank god — I have no idea how to write without them
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Replying to @conorsen
They're useful! And semicolons have too many rules...
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Replying to @conorsen
That's load bearing
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Replying to @conorsen
Never stopped
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Replying to @conorsen
Next up: “it’s not just X, it’s Y” sentence structures.
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Replying to @conorsen
Only way they’ll be able to tell a human wrote it is the em dashes
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Replying to @conorsen
I used to love using the em dash, until I read Elements of Style where they said it's better to use commas, so that's what I started doing. Also, some keyboards make the em dash kind of hard to type.
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Replying to @conorsen
Only if you want to look like you’re using a discount model.
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Replying to @conorsen
I got two today.
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Replying to @conorsen
It is actually a huge shift in how these models handle writing style.
AGTP
@AGTPinsights
Sep 25
Anthropic's Claude Opus 5.5 just quietly killed the em dash. Here's what you need to know. Opus 5.5 launched on September 22, 2026 as the first model in Anthropic's new 5.5 family. Anthropic says it leads in agentic coding and knowledge work, runs about 40% cheaper than Opus 5 on typical workloads, and outputs over 30% faster. Arena.ai analyzed how Opus 5.5 writes versus Opus 5 across high reasoning Text Arena outputs. 10 of 12 writing measures moved in a better direction, making Opus 5.5 easier to read than any prior Claude model. Key numbers: - Long content words: down from 41.7% to 38.6%, lowest of any Claude model - Em dashes: down about 95% - Semicolons: down about 73% - Sentence length: down about 17% on average - Answer quality: up about 6% The change went viral after AI consultant Peter Gostev posted "RIP em dash" quoting Arena.ai's thread, prompting writers online to joke they can finally reclaim the punctuation mark for themselves.
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Replying to @conorsen
Finally.
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