Back in January, Slate's Farhad Manjoo set the blogosphere a-boil with a vitriolic philippic against the evils of ever placing two spaces at the end of a sentence. A veritable Greek chorus rushed to add its voices to his, including no less a figure than John Scalzi. On the flip side, Megan McArdle of The Atlantic spearheaded the opposition, and a flurry of spirited defenses of the two-space tradition set out to demolish the arguments at the center of Manjoo's emotional diatribe.
I stayed out of the fray at the time. I've already had what I hoped would be my definitive say about sentence spacing, and in fact I spent a lot of time last year thinking through some significant ameliorations of my former strict insistence on two spaces. It was never my intention, back in 1995 when I first posted "Proper Manuscript Format" on the web, to become a de facto formatting guru, but it happened anyway. This means I still get frequent emails from aspiring writers who want to know why this authority or that is telling them they should never ever, on pain of banishment to editorial hell, put two spaces after a sentence.
It's probably past time for me to expand further on my position that, while one space is fast becoming the reigning standard, it's still perfectly fine to use two if that's what you prefer.
We are all by now familiar with the argument that the two-space rule is a relic of the typewriter era, outmoded in these days of computer typography and proportional fonts. I am willing to admit this, to a point (even as I am unwilling to unlearn a practice that, through more than three decades of dedicated typing, has become as much a part of me as my two thumbs). But where this argument falls short is in its failure to recognize that the commercial publishing industry, at least in the U.S., had already begun phasing out the two-space rule sixty years agoat the very height of the typewriter era. It wasn't the advent of the personal computer that made the practice begin to change. It was much earlier advancements in high-volume mechanical typesetting.
Before the 1950s, it's likely your reading material would have contained more space between sentences than we're used to seeing now. But these days single-spacing is what we've come to expect. It's what most of us have grown up with. It's the only standard we've ever known for finished copy.
But there's the rub. Finished copy. The stuff you'd see in a book, in a magazine, in a newspaper, or even on a website like this one. Material that's been through some kind of editing and production process, and has been rendered in a way suitable for presentation to the general reader.
What people who speak in loud voices about sentence spacing are usually referring to, though, are submission manuscripts, and a submission manuscript is not finished copy. Even as the two-space rule was vanishing in print, it hung around in the world of the typewritten manuscript for a very practical reason. It makes the writer's intention about where each sentence ends perfectly clear.
To borrow a metaphor from the online world, a novel manuscript is more like the source code for a book than it is like an actual book. It is a product intended for a very specialized audiencebook editors, most of whom are accustomed to its particular quirks. In fact, editors rely on those quirks to help them get their jobs done. A manuscript is not a product intended for a general reader. It is not required to conform to the needs or expectations of a general reader.
Now, as I've conceded many times in these posts, things are changing. The old standards and practices are giving way to newer ones. In many important ways, the gap between the creation of a piece of writing and its presentation to the reader is narrowing. But it's absurd to insist that two spaces is always wrong in a manuscript most readers are never going to see. It becomes even more absurd when you consider the utter lack of an outcry in favor of single line-spacing in manuscripts (a change that would far more obviously bring that format in line with standards for printed material). A manuscript is not finished copy and does not need to look like it.
To use another metaphor from the web world, I think most of the furor over sentence spacing stems from confusing our data layer with our presentation layer. As I'm composing this post right now, I'm putting two spaces between sentences. But as you read it, you're almost certainly seeing only one space. That's because your web browser does the production work of styling the text to conform with generally accepted standards for finished copy. If you're using a browser that allows you to look at a site's source HTML, you can right-click on this page and bring up what is essentially the manuscript version of this post. When you do, you'll see two spaces between sentences. But the fact that I typed those extra spaces in no way interferes with your ability to view the finished copy the "right" way.
I'm not saying you can't use one space in your manuscripts if you want. I'm only saying the writers who want to use two spaces are not wrong. It's a non-issue, and the fact that no professional editor or agent has ever gotten on my case about it only strengthens my point.
I would go further, though, and suggest that when someone tells you how using two spaces between sentences makes you a bad and stupid person, that someone is just an ass.