. . . that is the question. It is amazing how the vehemence with which a position is held is in inverse proportion with its importance. In the King James Version of the Bible, Matthew 5:18 is rendered as "For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled." Which says that the law will not be changed in the slightest degree. Jot is a corruption of Greek iota, in turn a corruption of yod - י - the smallest Hebrew letter and tittle is the diacritical mark that we put on top of i and j; who says we don't have accents in English? ANNyway, what we are concerned with today is is neither jot nor tittle but the much more important issue of whether you should put two spaces after a " . " [full stop = period for yankee-dogs] or just put one.
Somewhere along the way, I was taught that you should put .<space><space> but ,<space> and ;<space>. It wasn't in school because typewriters weren't invented when I was in school, so it was probably in Graduate School in Boston. But I've heard a lot of people saying that this is just too 19thC altogether and I should get with the .<space> programme. But I don't feel strongly either way and I'm not about to correct it if students follow one regime or the other or even if they apply the two options indiscriminately . . . nope, I have enough on my plate dealing with rogue apostrophe's. I think I'll have to change the habits of a life-time because the blogspot editor translates the first of my two <space>s as " " which is HTML for non-breaking space which can make a mess of line-feeds and carriage-returns and make my posts
ragged and unprofessional.
plagiarised someone (as you do) "Nothing Says Over 40 Like Two Spaces after a Period!" [and see L]. Well that's pretty clear. A nerd from Slate is rather more cross and certain with "Space Invaders: Why you should never, ever use two spaces after a period." There is, of course, a counter-position [without which there would be no war] from the Chicago Manual of Style blog : "About two spaces after a period. As a US Marine, I know that what’s right is right and you are wrong. I declare it once and for all aesthetically more appealing to have two spaces after a period. If you refuse to alter your bullheadedness, I will petition the commandant to allow me to take one Marine detail to conquer your organization and impose my rule. Thou shalt place two spaces after a period. Period. Semper Fidelis." Ooooh frighty me! Lifehacker warns about .<space><space> age discrimination in preparing CVs/resumés.
The standard trope is that we use .<space><space> because that was the only way that you could give more weight to the full-stop with an old fashioned typewriter that for mechanical reasons had to deliver fixed-width fonts like Courier: in which I've written this sentence. But you might reflect that such crude typography only held sway for about 120 years between, say, 1880 when typewriters replaced a clean copperplate hand written with a quill pen and, say, 2000 when my aged-77 Uncle embraced a word-processor to write his letters. In my research into the question, I've had an education in whether the tail or the dog was wagging the spaces.
short overview of a couple of centuries of typography showing that the conventions evolve. And hey, they are just conventions like its vs it's [see last para of my review] and the sky won't fall if you encounter someone who marches to a different convention/drum. Moveable type, however, has been spreading the word since 23 February 1455, the traditional date for when Gutenberg published his Bible; [R ALEPH quomodo sedit sola civitas plena populo facta est quasi vidua domina gentium princeps provinciarum facta est sub tributo BETH] that's a staggering 560 years ago yesterday.
But you should always go with the flow if it doesn't cost you too much: "As a practical matter, however, there is nothing wrong with using two spaces after concluding punctuation marks unless an instructor or editor requests that you do otherwise." This is what scientists do in response to the inane and ill-informed comments that referees have made about their papers when they come back from a round of peer-review. It's galling to accede to their fatuous suggestions but easier for everyone if you just rewrite your paper to tick their boxes. When their helpful suggestion will require your student to soend another 6 months at the lab-bench - that's when you polish off your Diploma in Assertiveness and start fighting your corner.