When I was in eighth grade, I took a typing class. The teacher was a no-nonsense woman who drilled into us the rules of typography. Tab to indent a new paragraph, Shift to capitalize a new sentence, and space bar twice after each period.
A polemic in Slate by technology writer Farhad Manjoo excoriates the persistence of outdated rules like two spaces between sentences. It seems that when typewriters could handle only fonts like Courier in which all the characters were the same size, putting two spaces after each sentence made sense. But for decades now we’ve had access to fonts with proportional sizing, so it’s not as necessary to mark the end of sentences with exaggerated space.
One space after the period is simpler and more elegant. Notice the difference between this sentence and the previous one and the two spaces after this sentence. Yet, there are still many writers who cling to the two space rule mostly because that was how they learned it. Like with other seemingly inviolate rules (no split infinitives, don’t end a sentence with a preposition), this one is based on nothing other than tradition.
Too many strict rules can make our writing stilted. We’ve given up the typewriter, so why not get rid of the norms that came with it?