Single Spaced
Having had this argument a few times, it makes me very happy to read Slate’s takedown of double-spacing after sentences:
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.
Update (1/15/11): Apparently The Bluebook style guide for legal writing suggests two spaces.
Hi, I'm 
This is great. Although the issue of single space versus double space may seem of little issue to some people, it caused a horrible crisis in my university’s department. The APA 6th edition was released twice. The first release included the rule that there should be two spaces after a sentence; thus, every TA, professor, writer had to go back and re-format all of our work. Well, then the APA basically did a “whoops” and re-released the 6th edition, with the single space rule. I would love (yes really) to meet the panel of people who decided that spacing needed to be changed. Unless they are incredibly active in environmental causes, they need more to do.
(signed, a geek).
What a quirky thing. As memory serves, I was taught in mandatory typing class at the all-boys Christian Brothers High School that two spaces after each period was the rule. In that regard, I’ve never looked back. However, given that so many other things they taught have come into question, why should I be surprised? And yet, I’ve always found the ‘rule’ helpful in following text.
It just goes to show the heavy burden of responsibility that our teaches have and how easy it is to lead young minds astray.
It also proves once again the prescience of The Firesign Theatre’s apocryphal line: “EVERYTHING YOU KNOW IS WRONG!”
This is a conspiracy by everyone under 40 … because those of us past that point will take every shred of assistance at reading small print — including more SPACE! BOO HOO, I hate this rule and I ain’t changin’!