“Typing two spaces after a period is totally, completely, utterly, and inarguably wrong.” So observes Farhad Manjoo, in a well-reasoned article entitled “Space Invaders: Why you should never, ever use two spaces after a period.” This is not a matter of opinion; it’s a matter of fact.
I know from personal experience that most well-educated people who are not typographers disagree with the last sentence. They think it’s a matter of opinion, and they think that Manjoo’s opinion is incorrect. But they’re wrong: “totally, completely, utterly, and inarguably” so, as Manjoo points out. My personal experience comes from trying to persuade my colleagues that using two spaces looks amateurish and using one space looks professional. They disagree, because they all learned typing from someone who had used a manual typewriter, not a computer. But the one-space rule is not a new one; it’s over 100 years old, easily predating computers — but not typesetting machines. Manjoo explains:
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.
Take this “every modern typographer” seriously. When I participated in typography courses, there was no disagreement. When I worked with graphic designers on books, there was no disagreement. When I did consulting work for a typesetting company, there was no disagreement. In fact, everyone was so worked up about the subject that one employee seriously proposed charging a whole lot of money for a plugin that would automatically delete the extraneous space. I have seen what Manjoo writes about:
Type professionals can get amusingly—if justifiably—overworked about spaces. “Forget about tolerating differences of opinion: typographically speaking, typing two spaces before the start of a new sentence is absolutely, unequivocally wrong,” Ilene Strizver, who runs a typographic consulting firm The Type Studio, once wrote. “When I see two spaces I shake my head and I go, Aye yay yay,” she told me. “I talk about ‘type crimes’ often, and in terms of what you can do wrong, this one deserves life imprisonment. It’s a pure sign of amateur typography.”
So there! Case closed.