This post has been a long time coming, but I appreciate everyone's patience during my maternity leave! Question marks are one of the most common basic types of punctuation. However, they are one of the easiest to misuse, so I wanted to include them in this series to clarify the rules, exceptions, and conflicting style choices.
There are exactly four situations in which a question mark should be used: after a direct question, after a sentence that includes both a statement and a question, after a rhetorical question, and with interrogative dialogue. Never use a question mark after an indirect question.
Direct vs. Indirect Questions
Direct questions are interrogative sentences that directly ask the reader (or another character) something and demand a direct answer. They typically start with why, when, how, what, where, could, should, would, if, or will.
Example A: Why did you come home so late? Example B: When was the last time she talked to you?
Indirect questions are statements and should end with a period. They simply express a thought and don’t require a direct answer. You’ll know that a sentence is an indirect question by the placement of the interrogative key words; rather than starting the sentence, they will be found in the middle.
Example A: I wonder where my shoes are. Example B: I asked John what he had eaten for lunch. Example C: Suzy wanted to know if I had time to look over her paper.
Be careful to distinguish between an indirect question and an embedded question, which does require a question mark at the end.
Example: I wonder: what would he say if I asked him out?
…which is different from…
I wonder what he would say if I asked him out.
They key is in the placement of the two words “would” and “he.” When the key interrogative word comes first, the sentence becomes a question. When the subject/pronoun comes first, the sentence becomes a statement/indirect question.
Statement/Question Sentences
Sentences that include both a statement and a question—mixed sentences—should also end with a question mark. The emphasis is placed on the interrogative predicate in those cases, which means that the overall sentence becomes interrogative itself. And following the punctuation hierarchy, a question mark overrides a period in every case.
Example: It’s going to rain soon, isn’t it?
Rhetorical Questions
Rhetorical questions are those requiring no answer. They are often asked with a sarcastic tone or in order to express a feeling. And while some sources argue that these types of questions should end in periods since there isn’t really an expected response, I strongly disagree and insist that they end with a question mark. Here’s why.
This type of sentence still presents a question, and using period to end the sentence could cause potential confusion for the reader as far as interpreting the correct meaning of the sentence.
Incorrect: What do I have to do to get noticed around here. (Even Microsoft Word flags the punctuation as incorrect, by the way.) The person asking the question isn’t looking for a direct answer so much as they are expressing their frustration.
However, apart from even looking incorrect, this sentence is still a question and should be punctuated as such.
Correct: What do I have to do to get noticed around here?
If you still need convincing that a question mark is the more appropriate punctuation, look at the historical account of the question mark. The standard use of the punctuation with this type of sentence actually derived from a specific punctuation mark that was the reverse image of the standard one: http://en.wikipedia.org/wiki/Question_mark#Stylistic_variants. Its use just died out sometime in the 17th century.
Question Marks and Quotation Marks
As mentioned in a previous article of mine about quotation marks, question marks should be placed logically within the sentence. If the overall statement is a question, the question mark should fall outside the parenthesis. If only the quoted material is interrogative, the question mark should go inside the quotation marks. And as with any other sentence, the question mark always overrides a period.
Example A: What do you mean when you say, “We’ll see”? Example B: I asked Sarah, “When do you think you’ll be finished?”
(Notice that the question mark is the only ending punctuation in both cases.)
Other Stylistic Differences
Lastly, there can be some stylistic differences that truly depend on the type of piece you are writing. For instance, if you are writing a work of fiction, you might choose to keep the first letter of a series of questions lowercase.
Example: Where are you going? the mall? the movies? to a restaurant?
That is perfectly acceptable with an informal piece. However, because they are considered new sentences whereby the question mark is replacing a period, my personal preference (and the style you should probably use if you are writing a more formal piece) is to capitalize the beginning of each question:
Where are you going? The mall? The movies? To a restaurant?
Word also flags the lowercase punctuation here as incorrect, just as it did with the period at the end of a rhetorical question.
Overall, question marks are pretty simple and straight forward. Just take a logical approach, and you’ll have the hang of them in no time.