Grammatical Interlude: The Two Acceptable Uses of Quotation Marks
Grammatical prescriptivism annoys me to no end. (No ending sentences with prepositions? Ridiculous! Don’t split infinitives? Poppycock!) Well, except when I do it…
There are exactly two valid uses of quotation marks: when you mean something literally, and when you mean something nonliterally. It ought to be hard to mess that up. But the following are not valid uses:
- I really, truly, extra mean this! I wasn’t going to mention this one because I presume that you (dear reader of Messy Matters) have never done this, but the blog of unnecessary quotes is just too funny. And I suppose it is a bit confusing: italics can sometimes serve the function of quotation marks (read on) but not the other way around.
On to more the more literate misuses (admit it, you’ve done these):
- I’m not going to tell you what I mean by this. E.g., “the result is ‘nearly’ optimal” by which the author means “the result is nearly optimal, for some definition of ‘nearly’, which I can’t be bothered to specify.”
- This sounds too colloquial/informal/idiomatic. E.g., “The subjects got ‘carried away’.” The author here is thinking, “this sounds too colloquial or idiomatic for formal writing but it’s OK because I’m not really writing it, I’m just quoting a more informal version of myself.” Please. Just write it or don’t write it. The only exception is when you expect the idiom to be unknown to the reader. In that case, the second acceptable usage below applies.
- I’m coining this term/phrase or introducing terminology. Use italics instead. (“We say that an allocation is satisficing if…”) Exception: it is acceptable if the usage is also literal. (“We use the term ‘satisficing’ to refer to…” Though italics are acceptable here as well.)
Which brings us to the two acceptable usages:
- I mean this literally. I’m referring to the word or phrase itself. E.g., “‘Promulgate’ is hard to pronounce.” Or, “Alice said ‘Look out!'” Another instance of this rule is referring to works by title, with the slew of exceptions that certain titles, like books and movies, should be italicized rather than quoted. There are also other times when italics may substitute for quotation marks, such as in the first example with the word promulgate. 
- I don’t mean this literally. You can use scare quotes when something is not the right word or phrase. Of course what I really mean by “not the right word” is that it simultaneously is and isn’t the right word. E.g., “the player then ‘wins’ with a loss of $100” (they technically won but really they lost). Or if the word is accurate only loosely by analogy, e.g., “the program bids ‘spitefully’” (there’s a tit-for-tat aspect to its bidding but, being a computer, it doesn’t actually have spite). Wrapping something in scare quotes is like adding a parenthetical “not really”. It should be done sparingly; typically only when the nonliteral usage might be confusing if not “called out”.
P.S. If the quotation marks in the last sentence were like fingernails on a blackboard to you then you didn’t need to read any of this. And, ironically, you’re likely the only one who didn’t find this all a painfully pedantic waste of time!
EDIT: Per Hartman’s Law of Prescriptivist Retaliation I had to fix a couple errors since this went to press (embarrassingly, “slough” instead of “slew”). Also, thank you to Eva Revesz, Kevin Lochner, and Reema Bennekaa for commenting on drafts of this.
Illustration by Kelly Savage.
 There’s little obvious rhyme or reason to these quotes-vs-italics rules but I believe the principle is just this: Both quotation marks and italics are serving the same functional purpose (marking a word or phrase as literal) but with different forms to suggest various dichotomies, such as book titles vs. chapters within a book. Although even I couldn’t bring myself to care if you violated these conventions, as long as you’re internally consistent.