In a recent question, a user complained that one of their answers (10k+ link at the moment; screenshot answer now undeleted, see the answer timeline for more details) was unfairly flagged as plagiarism and summarily deleted.

The OP there has also asked for no further discussion to take place there (though in my view the OP has no such right - they can ragequit if they want to, but they don't get to decide what others can and cannot talk about) and a moderator has closed that meta question (again, completely unjustified in my view, but oh well). Since the discussion there has been shut off prematurely, I'm posting this as a separate thread.

In this specific case, it seems to me that:

  • There is no plagiarism of the text. There is some indication that the answer text (10k+ link) is indeed based on this page, but there is nothing in the text that I would classify as plagiarism. The answer could benefit from citing the source, if that is indeed the page the OP consulted, but the paraphrased text is re-structured enough that it is clear that they are the OP's own words.

  • There is an unattributed use of this image. This is an academic problem (always cite your source), and it is not clear that this site is licensed to reuse that image, but this is in no way a fatal flaw in the answer.

  • The answer contributes content above and beyond the specified source. This is evident from even a cursory comparison, as the image of the Apollo heat shield, and its associated text, is absent from the purported source.

  • The clear conclusion is that Suzu Hirose's claim of plagiarism in a comment is completely overblown, and at best an example of carelessness when making such a flippant remark.

  • The moderator action to delete this post seems to me to be completely overblown. The moderator seems to have taken Suzu Hirose's comment at face value, and seems to have thought that the text was taken directly from there, when a reasonable inspection shows isn't the case. The moderator's tone also seems off to me.

  • The moderator comment, on balance, seems OK - the moderator has expressed displeasure with the answer, and it does fall to the OP to say something along the lines of "hey, read the post again, there's nothing like that going on here!".

  • On those lines, the immediate deletion of the post seems completely unjustified to me. Deletion could be justified if the plagiarism was actually there, and(/or?) the OP had been given time to respond (and possibly failed to), but this does not tick any of the boxes.

In terms of specific outcomes that I would like to see happen, the answer in question should be undeleted - there is no reason for it to be out of action, because it contains no actual plagiarism. After that, someone (ideally the OP, but they seem to have left) should edit in the image attributions, and probably add the source as a further-reading link, but those are minor problems.

In general, I read this as a localized instance, and I don't think it is representative of a wider trend. However, there's also no harm in asking the moderators to be extra careful, in general, when vetting accusations of plagiarism, to check that the plagiarism is actually there before summarily deleting any posts.

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    $\begingroup$ I have undeleted the post in question in order to have a reputation-barrier free meta discussion about this case. If the initial deletion is found to have been the correct course of action, it will be deleted again. $\endgroup$
    – ACuriousMind Mod
    Commented Oct 26, 2016 at 15:21
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    $\begingroup$ Thank you very much for taking the time to post the above, I only saw it 15 minutes ago. I still wince, despite anonymity, when I realize that I had the absolute gall to try to tell other people what to do, in the last paragraph of my post. Thanks again for your post, (and this is not a platitude), which will benefit all concerned. $\endgroup$
    – user108787
    Commented Oct 26, 2016 at 20:20
  • 2
    $\begingroup$ @CountTo10 No worries, and take it easy. We all end up encountering situations that rile us up, here as in the rest of the 'net. In those cases, it really helps to breathe, step away, sleep on it, and come back the next day. Just fix the problems and move on. $\endgroup$ Commented Oct 26, 2016 at 21:00
  • $\begingroup$ Related: meta.english.stackexchange.com/q/9602/72565 $\endgroup$
    – rob Mod
    Commented Oct 28, 2016 at 21:13

3 Answers 3


The fault here is mine. I didn't take enough care in checking the match between the post and the proposed source.

I can only offer by apologies and delete the accusatory comment on the post.

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    $\begingroup$ As said, 'To err is human'. Mods are not infallible. It was bit hasty decision on a single event to leave a site. But yeh, plagiarism should be taken care very minutely. +1. $\endgroup$
    – user36790
    Commented Oct 26, 2016 at 17:10
  • $\begingroup$ Yeah, pretty much. Mistakes happen, they get fixed, we can move on. $\endgroup$ Commented Oct 26, 2016 at 17:50
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    $\begingroup$ @dmckee. Sincere apologies for the rant, I only saw your post now. I honestly don't know where you get the time to moderate and for the reasons I have listed on the post, I overreacted. This sentence may or may not make much sense to you, but your comment yesterday on physics job is to predict properly (and, if I understand you correctly), by implication we can be less concerned about math related issues such as Godel's Incompleteness Theorem, renormalization, if that is still an issue :), etc) really struck home and I will remember it and move on. Thank you. $\endgroup$
    – user108787
    Commented Oct 26, 2016 at 19:34

I want to address the accusation of plagiarism. This is definitely a supplementary (not full) answer, but the level of appropriateness of the response could be judged differently depending on whether there actually was plagiarism or not, so it is potentially relevant information. (Also, although this is my answer, I believe it reflects the consensus of all the moderators, so you can take this as semi-official.)

The answer includes this passage:

As the fireball travels through the air, a layer of extremely hot gas forms in front of the meteor, which is compressed by collisions with atmospheric atoms and molecules. This results in a "hydrodynamic cushion" that provides the meteor with a measure of protection from direct collisions,

This hydrodynamic cushion creates two macrostates ahead of the meteor: One is at 3500-5000K, and one at 10000K.

Meanwhile, the source includes this passage:

As the fireball travels through the atmosphere, the hot vapor from ablation is compressed by collisions with atmospheric atoms and molecules. This creates an air cap or hydrodynamic cushion that protects the meteor from direct collisions, which can be seen in the figure below.

[figure omitted]

This barrier creates two macrostates in front of the meteor: One at 3500-5000K, which we will call the main spectrum, and one at 10000K, which we will call the second spectrum.

The similarity of these two passages, specifically including phrases like

  • "As the fireball travels through the [air/atmosphere]"
  • "compressed by collisions with atmospheric atoms and molecules"
  • "This [hydrodynamic cushion/barrier] creates two macrostates ahead of the meteor"

without any indication of the relationship between the source text and the answer text qualifies this part of the answer as plagiarism.

To prevent this from being plagiarism, one could add an indicator like, "To paraphrase this site," along with clear marking of where the paraphrasing begins and ends, and that would be one way to bring the post in line with our referencing guidelines.

Again, this answer only concerns the existence of an instance of plagiarism, and not (directly) the appropriateness of the response given that an instance exists.

  • $\begingroup$ Thank you for this response. Could you expand it to include what you think the appropriate should be in a case like this? $\endgroup$ Commented Oct 28, 2016 at 13:59
  • $\begingroup$ Appropriate what? I've posted my thoughts on appropriate responses to plagiarism as answers to other questions about that topic, if that's what you meant. $\endgroup$
    – David Z
    Commented Oct 28, 2016 at 14:57
  • $\begingroup$ Apologies - yeah, appropriate response. $\endgroup$ Commented Oct 28, 2016 at 15:10
  • $\begingroup$ I do find the voting on your and John's answers quite interesting, btw - it seems this question may well hit the precise sweet spot where 50% of the site users think it's OK and 50% think it goes too far (or at least without proper attribution). $\endgroup$ Commented Oct 28, 2016 at 15:12
  • $\begingroup$ Yeah, it's interesting. Though as far as the mods are concerned, this was an instance of plagiarism, and regardless of how the voting goes on this answer we're going to treat it as such. If the community at large would like to set a particular standard for what constitutes plagiarism, that could be a matter for a separate meta post. $\endgroup$
    – David Z
    Commented Oct 28, 2016 at 16:31
  • $\begingroup$ By 'treating it as such', do you mean editing in better attribution, or something heavier? (I wouldn't be opposed to the former - the current form is still too light in attributing the sources for the text imo.) $\endgroup$ Commented Oct 28, 2016 at 16:34
  • $\begingroup$ How was this original source identified? $\endgroup$
    – innisfree
    Commented Nov 3, 2016 at 13:07
  • $\begingroup$ @innisfree It shouldn't matter, but someone commented on the answer with a link to the source. $\endgroup$
    – David Z
    Commented Nov 3, 2016 at 19:18
  • $\begingroup$ If it we want to be objective, we could use plagiarism software once it was suspected and set a threshold for similarity between answer and source. $\endgroup$
    – innisfree
    Commented Nov 3, 2016 at 21:11
  • $\begingroup$ @innisfree Then the subjectivity enters in choosing where we set the threshold. Making that choice is probably going to be a complicated process. Still, if people would really like it, I'm not opposed to trying it - that is, when there is an accusation of plagiarism from a known source, we run a program to determine the degree of similarity and thus determine whether the moderators should consider it plagiarism. Feel free to propose that in a new meta post if you like. $\endgroup$
    – David Z
    Commented Nov 3, 2016 at 23:22

This is really a comment to DavidZ's answer, but it got a bit long and I'd also be interested to see if others agree with me (i.e. how this answer gets voted).

My point is that I think David sets an unreasonably high benchmark for what constitutes plagiarism. If I look back through my own answers then there have been many occasions where I've done little more than paraphrase an article I've found on the Internet. This is what CountTo10 did, and I cannot condemn him for plagiarism unless I want to tar myself with the same brush.

There have been many occasions when I've seen a question that I could not answer and thought it was interesting. So I've gone off and Googled until I understood the subject. Then if I'm confident I understood it correctly I would write an answer, and inevitably that answer bore a considerable similarity to the articles I'd read.

This seems entirely reasonable to me. Plagiarism implies you are benefiting from someone else's work, and it offends our sense of fairness. In an academic context it generally means you're trying to advance your career by parasitising other researchers and everyone finds that repugnant. But the reason we try to answer questions here is to be helpful. No-one's career is going to be advanced by posting here. A high rep on the Physics SE does not bring fame, fortune and the intimate attentions of whatever gender you favour - you can trust me on this.

Of course there limits. If someone has just copied and pasted large parts of their answer verbatim few of us would be impressed. And if I have relied heavily on a particular article I would cite it on some vague grounds that it seems good karma. But I don't think the fact an answer relies heavily on another article makes it plagiarism is the sense normally used in academia, especially when considerable effort has gone into writing the answer.

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    $\begingroup$ What we're talking about here is not just an answer "relying heavily" on an article. It's verbatim copying of several phrases, with the occasional modified word: "As the fireball travels through the [air/atmosphere]", "compressed by collisions with atmospheric atoms and molecules", "This [hydrodynamic cushion/barrier] creates two macrostates ahead of the meteor", and so on. $\endgroup$
    – David Z
    Commented Oct 28, 2016 at 8:41
  • $\begingroup$ The golden rule of this site with these issues seems to be move on, so I just want to thank you for taking the time to write a very clear and (entertaining) answer . I saw your above post 10 minutes ago, sorry for not responding earlier. $\endgroup$
    – user108787
    Commented Oct 28, 2016 at 16:13

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