Where to draw the line in "plagiarism" of earlier answers?

Question

I've just been downvoted for "plagiarism", in that I subsequently edited my own answer to include a reference that was already present in someone else's.

It so happens that in this particular case I was already aware of the reference when I first made my post, but I'm not sure that's relevant. In fact I didn't use it originally because while constructing my answer, and searching for earlier usages, I'd discovered an older one I wasn't familiar with. I just wanted to post my half-complete answer while I looked into a possible connection.

Is there a general consensus on EL&U etiquette for this situation? Even as I ask this, I'm aware it might be thought inappropriate to post an answer that might well be revised/expanded shortly afterwards, quite apart from the possibility of replicating another's references.

I've no wish to defend any particular stance in this area too strongly, but I will just say that unless an answer seems to consist almost entirely of the same content as one single other, I'm inclined to think there's nothing wrong. Even to the extent that a single new answer formed entirely by combining two or more existing ones may actually be desirable.

To my mind the primary aim is to end up with a single answer that's unequivocably "correct" and better than all others. If that can be achieved by combining two "half-right" answers, and the existing posters haven't arranged among themselves to do this, I don't really see much of a problem.

Am I out of touch with the zeitgeist here?

Answer 1

I think "borrowing" bits from other answers on this site in an attempt to make your answer more complete is ok—especially if the bit being borrowed has spurred your own thinking on the question and you wish to include it in your answer as a springboard for further insight.

In such cases, simply giving a nod to the other user within the body of your answer (e.g. "As @so-and-so points out,") is good etiquette. This will not only alert the original answerer, but also direct users to the other's presumably good answer. I think this is a good rule to follow even if you were planning on including the information in your answer but were beaten to the punch line, so to speak.

If you recall, you and I had a similar situation at the question What does “pax” mean in the context of the apartment rental? I found an antedating of the usage which you rolled into your accepted answer. At my request, you kindly credited me. Collaboration of this sort, with internal citations, is a good thing and should avoid any claims of plagiarism.

Answer 2

The difference between an acceptable answer, and one that is not acceptable depends from how much has been copied from the answer given from the other user, and how much text is added to the new question; if I repeat what I said from another user, and I add "This is what I think." then the new answer should be deleted.

I would make a distinction for some cases.

• If I write in my answer what reported by a dictionary, and somebody else before me reported what found in another dictionary, and the definitions completely, or partially, match then I didn't plagiarized the previous answer. It would be if I say to report what I found in another dictionary, and then I write the same answer already given, instead of writing what I found in the dictionary I am referring to.
• If two different users each write an answer, but the answer to the question is the combination of both the answers, then writing an answer that combines both of them would not be plagiarism. By writing an answer, I don't mean the new answer is simply a copy-and-paste of both the previous answers, except that it can contains the same references used by the previous answers.