Some months ago I ran an article about why you shouldn’t double space after a period. The comments on the blog itself were from fellow editors and thus supportive, but the amount of angry (angry!) push-back that showed up on Facebook (my account and those of my friends who reposted) was astonishing.

I routinely have to do a search-and-replace on manuscripts I’m working on, and when I (politely, honest) tell the author we don’t do that anymore, he often resists. “But I’ve always used two spaces. Who says it’s wrong?”

If you don’t trust Your Editor, we could have a problem. But don’t mind me. Farhad Manjoo at Slate has the answer, and because I like to stir things up on occasion, let’s address this emotion-fraught issue again.

Who says two spaces after a period is wrong?

Typographers, that’s who. The people who study and design the typewritten word decided long ago that we should use one space, not two, between sentences. That convention was not arrived at casually. James Felici, author of the The Complete Manual of Typography, points out … [that] as typesetting became more widespread, its practitioners began to adopt best practices … typesetters in Europe began to settle on a single space around the early 20th century. America followed soon after.

Every modern typographer agrees on the one-space rule. It’s one of the canonical rules of the profession, in the same way that waiters know that the salad fork goes to the left of the dinner fork and fashion designers know to put men’s shirt buttons on the right and women’s on the left. Every major style guide—including the Modern Language Association Style Manual and the Chicago Manual of Style—prescribes a single space after a period.

There’s more in the article, of course. Have a look. The most important concern here, I think, is some teachers are still teaching the two-space method because that’s the way they learned it themselves. Yikes. Doctors and nurses, just to name one example, have to keep current with advances made in their profession, or they can’t practice. Human knowledge moves forward. Isn’t that the way it should be?

One space after a period, people. Don’t argue with me on this.

Tweet: Why you shouldn’t double space after a period. For real.
Tweet: One space after a period, people. Don’t argue with me on this.

Disclosure of Material Connection: I have not received any compensation for writing this post. I have no material connection to the brands, products, or services that I have mentioned. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: “Guides Concerning the Use of Endorsements and Testimonials in Advertising.”