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. (The Publications Manual of the American Psychological Association, used widely in the social sciences, allows for two spaces in draft manuscripts but recommends one space in published work.) Most ordinary people would know the one-space rule, too, if it weren't for a quirk of history. In the middle of the last century, a now-outmoded technology—the manual typewriter—invaded the American workplace. To accommodate that machine's shortcomings, everyone began to type wrong. And even though we no longer use typewriters, we all still type like we do.Told ya so.
Fortunately, the two-space specification will die out when the last people who remember using typewriters do the same...unlike the standard alphanumeric keyboard configuration, which will likely live on well past the point that advancing technology or an improvement in a specification should have made it obsolete (we write more clearly than we speak, and I can't yet see how voice recognition software will change that). People do have trouble with the process of change, though. That's why - unfortunately - I have to tools in both metric- and English-measurements and have to convert from Celsius to Fahrenheit when talking about the weather with colleagues overseas.
But it's not just a resistance to change that powers the persistence of our specifications; it's the fact that the technology and systems of tomorrow build on what is available today...which stands on the shoulders of yesterday. My favorite example of this involves the internet meme about the width of the Space Shuttle's booster rockets:
Well, there's an interesting extension of the story about railroad gauge and horses' behinds. When we see a Space Shuttle sitting on the launch pad, there are two big booster rockets attached to the sides of the main fuel tank. These are the solid rocket boosters, or SRBs. The SRBs are made by Thiokol at a factory in Utah. The engineers who designed the SRBs might have preferred to make them a bit fatter, but the SRBs had to be shipped by train from the factory to the launch site.Of course, Snopes has some issues with the specifics, but the broad idea that today's advanced transportation** is based on the limits of yesterday's technology still holds.
The railroad from the factory runs through a tunnel in the mountains. The SRBs had to fit through that tunnel. The tunnel is slightly wider than a railroad track, and the railroad track is about as wide as two horses' behinds.
So a major design feature of what is arguably the world's most advanced transportation system was originally determined by the width of a horse's ass.
So what's the moral of the story? If anything, it's more proof that we are limited: 1) by our own habits, 2) by the necessity of having to base our reaction to what's coming tomorrow on the modified, re-purposed thought and technology available today...and 3) that an awareness of why things are the way they are - knowledge of history - helps us to better understand the present (not to mention winning points of dispute with fellow co-workers).
*I couldn't resist; apologies if you were expecting something different...then again, it's your fault for thinking that in the first place, isn't it?
** or, that of the 1980's