I asked for examples of fragments you kept, and ones you fixed (attaching to another sentence, say) in revision. Why did you keep the one and fix the other? How do they differ? Here are some of the examples in Comments, and whatever thoughts I have-- what do you think?
The next thing Cory heard was running footsteps. The door flung open. Hit the wall in a tremendous thud. People ran in. Many of them. Boots crunched over glass.
I actually thought that "The door flung open" was a fragment, because of that little weirdity of English conjugation that has "flung" as both the past tense and the past participle (alas, "fling" doesn't follow the "sing" conjugation pattern, that is, we don't say, "Fling flang flung). So if you read "flung" as the past participle-- that is, Cory heard running footsteps, and then heard the door flung open, that's a fragment too, continuing the "what Cory heard" thought. But the next, "Hit the wall," obviously is a continuation of "The door's" actions-- flung open, hit the wall.
I don't actually like that "Many of them" fragment. I'd probably connect that to the sentence before-- People ran in, many of them, their boots crunching over glass. (And I'd suggest replacing "people" with something more interesting if possible.) I don't know why. Why? Maybe it's because this is continuous motion, not really a perception but an action, and it feels like it out to be in one sentence to convey the unity and the swiftness.
Hmm... it's maybe hard to justify the preference of one fragment over another! I wonder if it's like what Patricia said, that the first is has an implied subject (The door) with two predicates (flung, hit), so it's clear what the fragment means.
Patricia gives this example:
Jill entered the closed. Poked around a bit. Turned and left.
Patricia said: The implied subject in the last two sentences, of course, is Jill. But if those sentences are removed from context, they become incomplete because the subject is unknown.
That seems important to me. When does the fragment become truly incomplete, when the meaning is lost? We don't want that sort of fragment, right?
That of course doesn't explain why the fragment type most likely to set my teeth to hurting is:
He headed for New Paris. Which was west of town.
It's clear what that fragment means-- no confusion. I guess it's because there is NO reason for a fragment there, and that it indicates to me the writer really doesn't know what a sentence is.
There was no sigh that showed she didn't want to be responsible for me. No nothing. Just straight matter-of-fact, no big deal. Maybe it wasn't.
Another example. I have to say I had a lot more trouble with all the negatives-- no sigh... didn't want... no.... I wasn't sure what was happening there. I suspect there's always a danger of confusion when you're writing about something that -didn't- happen (the sigh that didn't happen, but if it did happen, would mean she didn't want to be responsible-- see the doubling of negativity there? NO sigh ...NOT responsible and using past tense --that showed-- rather than a conditional -- that would show-- adds to the confusion).
The problem with the fragments isn't that they're fragments, but rather that they seem alike and yet refer to different things. The "no nothing" must refer to "no sigh," while the "just straight matter of fact, no big deal" refers to... her attitude? Her lack of feeling a lack of responsibility? That is, what the second fragment refers to isn't clear in the sentence preceding it. Does it have to refer back? Maybe not, but it must go with something like "she felt"?
This is fragments as pronouns, almost, that is, they're referring back to an antecedent, and if it's not clear what the antecedent is, does that mean the fragment is "incomplete" because the meaning isn't clear? What do you think?
Grimes and I could go on to answer a noise complaint that had come in half an hour ago and, as usual, got kicked aside in favor of higher priority calls. In this case, criminal trespassing.
Me, I like colons, so I'd be more likely to have "higher priority calls: in this case, criminal trespassing." But that would be hard to do across a paragraph break. (That is, I don't think we would end a paragraph on anything but a period or other terminal punctuation. Well, I might end with a dash.)
The one thought I have is that the fragment is singular -- THIS case-- while the "antecedent" is plural -- calls. Might be worth going with... in favor of a higher priority call. That is, there's an actual CALL that kicked aside the complaint, so probably I'd suggest casting it in the singular.
Okay, so we might not have come to much of a conclusion of what makes a fragment acceptable. Patricia did have some categories that might be worth exploring:
When I think of fragments, I think of three kinds: (1) where the subject is implied but not specified; (2) prepositional phrases; and (3) nouns by themselves, often an exclamation.
Hmm. I can see good examples-- acceptable examples-- for all of those, but unacceptable ones too. Maybe it's a matter of taste, that is, "If I read a fragment and I want to connect it with a sentence or add a word or two to make it a sentence, that's a bad fragment. If I get something beneficial out of it, a sense of rhythm, emotion, voice, then it's a good fragment?"