A few of you may be wondering why nineteen questions just disappeared from the site. This meta post is meant to explain what just happened, and set a goal for how to handle similar situations in the future.

These posts were deleted because they were plagiarized. They were directly copied verbatim from other sources or websites. This is not acceptable for the Stack Exchange network. Copying or stealing others' work and claiming it as your own is ethically wrong, and devalues the work of others. In fact, since the source site had an explicit copyright notice, this could even be considered copyright violation.

The fact that many other users will also have their completely valid answers deleted is unfortunate. However, it is imperative that we set a certain standard of question quality, and plagiarism falls far, far below that quality line. This may seem unfair towards the users who have posted these answers, but it is necessary that no amount of copying or stealing from other sources can be tolerated. On a more positive note, this may encourage users to check for plagiarism more diligently (this specific situation went unnoticed for several weeks).

Moving forward from this particular situation, plagiarism is absolutely unsuitable for any Stack Exchange site. Please use an "other" flag on any copied posts you find, and they will be deleted promptly. After extensive discussion, a conclusion has been reached: Plagiarism is not okay, no matter what. Even if it means that legitimate answers have to go with them, plagiarized posts will always be removed immediately.

Please note that posts containing attribution are not plagiarized. They may be of low quality, but for them to count as plagiarism necessitates an absence of attribution.

  • 1
    $\begingroup$ Would you mind disclosing which questions were removed? $\endgroup$
    – SQB
    Oct 31, 2014 at 7:38
  • $\begingroup$ meta.puzzling.stackexchange.com/questions/1344/… may help identifying the root of this @SQB $\endgroup$
    – skv
    Oct 31, 2014 at 7:52
  • $\begingroup$ I didn't even notice the questions disappear, myself. Possibly because if the question was already done before, my eyes just glaze over them and I move onto another question. $\endgroup$
    – user88
    Oct 31, 2014 at 21:54
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    $\begingroup$ Is it okay if we either site the source, or reword the problem? $\endgroup$
    – Aura
    Nov 5, 2014 at 16:38
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    $\begingroup$ Why are we doing this? I thought it was the responsibility of copywrite owners to determine if we're in violation, not the community. I'm not defending plagiarism, I'm just not convinced we should be the plagiarism police. Is this "extensive discussion" here on meta, or otherwise public? I can't seem to find it. $\endgroup$
    – corsiKa
    Nov 10, 2014 at 17:45
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    $\begingroup$ @corsiKa Stack Exchange has a certain quality standard, and we want to live up to that reputation. The discussion mentioned was unfortunately done in a private moderator-only chatroom, but I could possibly make it public with the consent of all participants. $\endgroup$
    – Doorknob
    Nov 10, 2014 at 17:54
  • $\begingroup$ If it was in teacher's lounge, I can look up the transcript myself if I know the dates it occurred. I don't remember there being anything sent out about a pow-wow, but I would have loved to been in on this conversation. $\endgroup$
    – corsiKa
    Nov 10, 2014 at 17:56
  • $\begingroup$ @corsiKa Ah, apologies; I didn't realize you were a moderator. I've pinged you in TL with a transcript link. $\endgroup$
    – Doorknob
    Nov 10, 2014 at 18:48
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    $\begingroup$ In the future, when you do this, please take note of the questions deleted and present to us a list. I know that you probably did the right thing, but we should always have a paper trail. There is always the extremely unlikely possibility that the person who posted the question here is literally the person who invented the riddle and the other site's content may have been the plagiarism. It is always best to err on the side of caution. More importantly, you've really frustrated me with curiosity. $\endgroup$
    – Kingrames
    Sep 9, 2015 at 21:59

5 Answers 5


To start with the easy bit: copyright notices are red herrings. Take, as an example, the now deleted Air Crash Dilemma. A search for the key phrase:

bury the survivors?

turns up "About 94,700 results". Some of them are user contributions (blogs, forums, Facebook, etc.), but some sites have a copyright notice attached. Of course, that's meaningless because the riddle was a chestnut 30+ years ago when I first heard it. Whoever created the riddle has long ago lost the ability to claim any sort of ownership over it. Puzzling.SE users (nor moderators) can't be expected to enforce copyright violations, so our Content Policy explicitly makes it the responsibility of our "Designated Agent", currently an employee of Stack Exchange.

Our anti-plagiarism policy has no connection to copyright concerns. Rather it's directly a result of a notice on the bottom of every page:

user contributions licensed under cc by-sa 3.0 with attribution required

The two phrases in bold specify how user contributions to this site ought to be treated. We ask that you extend the same courtesy to authors that you receive here. To make a long story short: please don't pass someone else's work off as your own. To that end, use the blockquote syntax (> ) to set off quoted text and provide a link to your source (either a URL or the title/author of material found offline).

There are a few other things to consider, such as whether a post consists of a quote and nothing else, but the important bit of our plagiarism policy is that posts give credit where credit is due.

Now the trickier bit: what to do about puzzles that were obviously copied from somewhere else? Personally, I find the deletion on sight policy a little harsh; especially for questions. I like to think of problem posts as teaching opportunities and deleting questions does very little to teach people what they did wrong. My preference would be:

  1. Edit in the blockquote Markdown formatting to show where the quotation starts and ends.

  2. Add a link to the source. Obviously, for the "Where are the survivors buried?" question the link is unlikely to point to the inventor of the riddle. But if the text is simply copy-and-pasted, your can probably find the author of the wording of the riddle with a few seconds of Googling. If you can't find the exact wording, the puzzle is likely a chestnut and not plagiarized.

  3. Leave a short comment, such as:

    Hi there! Please don't copy-and-paste puzzles here as it runs afoul of our policy for giving credit where credit is due. Feel free to write puzzles in your own words, but don't forget to link to wherever you got the idea.

  4. (Optional) If you want to be generous, consider rewriting the puzzle yourself and/or adding additional commentary.

As I said in the beginning, it's darn common for puzzles to be passed around, often with exactly the same wording, from one site to another. Here at Stack Exchange we have a higher standard than most. It might be that you don't want these sorts of common knowledge puzzles on the site. If so, I recommend making that clear in the on topic help page. (While moderators may edit that page themselves, it's usually best to discuss the wording on meta first. This is doubly true of potentially disruptive policy changes.) If you do want them here, please help people ask them productively rather than deleting copied puzzles and solutions outright.

  • 3
    $\begingroup$ So we can copy/paste as long as we give credit and reference the source? $\endgroup$
    – user2174
    Nov 7, 2014 at 6:21
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    $\begingroup$ @Mathias Foster: I wouldn't say that. Giving credit for material you copied is sort of a minimum. In my dream world, people would take puzzles they found elsewhere and spruce them up so that they are interesting again. My only question here demonstrates the idea. $\endgroup$ Nov 8, 2014 at 0:23
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    $\begingroup$ "Of course, that's meaningless because the riddle was a chestnut 30+ years ago when I first heard it. Whoever created the riddle has long ago lost the ability to claim any sort of ownership over it." What, like the song "Happy Birthday", you mean? $\endgroup$
    – bye
    Nov 11, 2014 at 13:16
  • $\begingroup$ @Poldie: Sort of. If the "Happy Birthday to You" copyright holders found something on our that violated their rights, they would need to contact our designated agent. Enforcing copyright just isn't something users or moderators need to consider. But as I said, this is all a red herring to the issue at hand. $\endgroup$ Nov 11, 2014 at 17:01
  • $\begingroup$ @Alex Except that a US court ruled a couple of weeks ago (long after your comment was posted) that Warner/Chappell's claim to copyright on Happy Birthday extends only to a specific arrangement of the tune and that the lyrics and its melody are in the public domain. $\endgroup$ Oct 10, 2015 at 10:28

I have asked two questions that may be problematic:

If these questions are indeed an unallowable infringement of copyright, I would very much appreciate it if they weren't removed outright, but if I was notified instead, so I may rephrase them to remove the infringement.

  • 2
    $\begingroup$ Under almost all circumstances, we'll let you know when we delete something for plagiarism, particularly if it seems unintentional and/or is a first warning. $\endgroup$
    – user20
    Oct 31, 2014 at 16:19

I posted a puzzle today and I openly admit that I got it from another source. However the original puzzle is not listed in English. I don't want credit for the puzzle or make it look that I created it myself. I just thought it was a nice puzzle and wanted to share it with all you, my puzzle friends.

Is this tolerable or will my post be deleted?

This is my post: Mutation of aliens

  • 3
    $\begingroup$ All you need to do is provide attribution $\endgroup$
    – d'alar'cop
    Dec 5, 2014 at 15:14
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    $\begingroup$ Ok, I will provide my source in the original post! $\endgroup$ Dec 5, 2014 at 15:17

I think it's important that we also clarify what plagiarism is. I'm fairly sure that if you look long enough, you will find that every puzzle on here, no matter how easy or hard, has been posted somewhere before, be it online, as a plot point in a work of fiction, or in a collection of puzzles. For example, I doubt that puzzles that explicity mention Inspector Poirot, Sherlock holmes, or other semi-famous detectives, are thought up by the mind of the OP.

The past weekend, I've been on an archive binge in this SE, and I actually already heard or read most of the questions somewhere. from the 15 highest voted ones, I believe i've heard 10 or so before. the only one I can assuredly say I haven't heard before was the one about the automatic parking valet.

I think putting a pure blocking of "if this appears anywhere else online or in another medium, in any form, it's plagiarism, even if all names and references have been changed" would make this SE dead before it even starts, because, after 5000 years of writing and storytelling, someone who makes a new riddle probably wouldn't post it on here as their first idea. I'm not saying we should copy the classics verbatim, but we shouldn't just stop using them altogether.

I asked The robbery of the Black Forest Inn yesterday and am wondering to what extent this can be seen as plagiarism.

I got the idea from a Junior Detective mystery booklet about a detective. In the book, the protagonist got a visitor in a rainy British November. He could tell why the visitor was there because he came from the police headquarters, not his own home, and he could tell this because a fresh puddle at one end of his driveway did not have tracks leading from it, while this puddle would have been disturbed if he came from his own home.

is this also plagiarism? I mean, I used the general idea of tracking through the state of a puddle, but not the scene, and ideas can't be plagiarized, right?

  • $\begingroup$ We distinguish between works in the public domain and works under explicit copyright and/or unattributed works. If it's in the public domain, you still need to attribute it. If it's not in the public domain, you need copyright-holder permission to repost it anywhere. If it's copyrighted and challenged, it will be removed. $\endgroup$
    – user20
    Nov 4, 2014 at 6:19
  • $\begingroup$ The assertion “if you look long enough, you will find that every puzzle on here, no matter how easy or hard, has been posted somewhere before, be it online, as a plot point in a work of fiction, or in a collection of puzzles” is false and seems malign. The eight puzzles I've posted are new and haven't appeared anywhere else. See eg How high a tower of tiles can be made? and Unlocking a curiously-geared combination lock. $\endgroup$ Nov 5, 2014 at 4:25
  • $\begingroup$ @jwpat7 The combination lock puzzle is a variation on the classic rotating dial puzzle. Apart from that, most of your puzzles are classic mathematical or geometric conundrums, like traveling salesman. $\endgroup$
    – Nzall
    Nov 5, 2014 at 8:34

Surely the enforcement of the ban on plagiarism, which is not only a tort but a breach of the SE Terms of Service, isn't the job of moderators?

I realise a mod might be the first to notice an instance of plagiarism. So let them notify someone who acts on behalf of the company, which mods don't. Of course a non-mod can also do this. And it might be necessary to take action fast, especially in blatant cases, so let a moderator do that, pending an admin decision. If it's a moderator's role to enforce the ToS, then they'd be acting on behalf of the company, which they're not supposed to. The moderator agreement is very clear on that. It's not a moderator's role to enforce the ToS.

Contrary to what mod @Doorknob says, plagiarism has nothing whatsoever to do with quality. How good something is doesn't depend on who owns the rights to it. Aren't mods stepping outside their domain here?

Is this another case, as with the ban on non-individual accounts, of mods actually being unclear about the ToS, and the relationship between SE users and SE Incorporated that that document establishes - a relationship which is highly germane to the issue of plagiarism - but letting their position, which is supposed to be about the maintenance of the quality of site content, go to their heads?

  • $\begingroup$ Reason and argument for downvote, please. Your contribution to improving this answer would be welcome. $\endgroup$
    – h34
    Sep 9, 2015 at 21:22
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    $\begingroup$ Looks to me like like plagiarism is not a violation of the ToS, but rather of site policy. $\endgroup$ Sep 9, 2015 at 21:31
  • $\begingroup$ Plagiarism contravenes ToS point 3, either a) or c) or both. $\endgroup$
    – h34
    Sep 9, 2015 at 23:09
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    $\begingroup$ Ah yes, I see. So it looks like plagiarism violates ToS and site policy. I see where you're coming from, I would be nervous to see content removed because it was thought to violate a copyright, especially without an explicit request for removal from the copyright holder. But plagiarism is different, and in my view this is an issue of quality: a repository of puzzles is much nicer if the sources of the puzzles are included. To be sure I understand your position: are you saying puzzling.SE should not have a policy against plagiarism? $\endgroup$ Sep 10, 2015 at 0:33
  • 1
    $\begingroup$ I was thinking of the tort. "Plagiarism" covers the unattributed submission of work bought from the author. If the intended use was clear, that isn't a tort, wouldn't breach SE ToS, and shouldn't interest mods. In its own interests, SE Inc should enforce the rule against rights violation, even if indemnified against consequences (pocket depth). The problem with a "policy" as this is understood on SE is that it risks making mods into company agents. Lack of clarity here! I've got no problem with a rule saying users should state sources, including for specific ideas if that's what's desired. $\endgroup$
    – h34
    Sep 10, 2015 at 1:18
  • 1
    $\begingroup$ Or just guidance - "please state sources" - plus maybe a site-specific warning against rights violations and a reminder of the ToS. $\endgroup$
    – h34
    Sep 10, 2015 at 1:22

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