I flagged some comments 3 of which got declined.
1.Trouble solving $\int\sqrt{1-x^2} \, dx$
This says only Thankyou.
2.Baricenter of $4$ intersection points of parabola with circle lies on axis of parabola
This seems to be both "too-chatty" an "Not-constructive".
3.Baricenter of $4$ intersection points of parabola with circle lies on axis of parabola
Users are not obliged to provide a reason for downvote.
Here are detailed discussions in the questions: https://meta.stackoverflow.com/search?q=require+downvote+comment&submit=search

Seems like I misunderstood or there is some other criterea to decide which comments are not-constructive.
Please explain the current policy for deciding what kind of comments are called not constructive in detail. If there is not any canonical post about deciding a comment as not constructive then please make your answer an official policy in this regard.

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    $\begingroup$ «If it ain't broke, don't fix it» — and I don't see what problem you're trying to solve here $\endgroup$
    – Grigory M
    Feb 12, 2014 at 13:11
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    $\begingroup$ flagging of comments should be used if there is some real problem: a flame is starting or a long chatty discussion going in circles or something like this... $\endgroup$
    – Grigory M
    Feb 12, 2014 at 13:12
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    $\begingroup$ Comments are temporary this website is not a chit-chat. The real problem is that when i read some question or answer i too read the comments because they are sometimes useful. unconstructive or unuseful comments make waste of time. There should be only useful comments which should be knowledgeful. $\endgroup$
    – user103816
    Feb 12, 2014 at 13:16
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    $\begingroup$ Personally, I would get rid of the option to flag as "not constructive". $\endgroup$ Feb 12, 2014 at 13:26
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    $\begingroup$ @MichaelGreinecker sorry if you misinterpreted my question. I've edited my question. I am not asking for personal opinions. My question is straight forward: "What is the current policy". $\endgroup$
    – user103816
    Feb 12, 2014 at 14:47
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    $\begingroup$ @anupam My opinion translates to my handling of comment-flags. So far, I've only deleted comments flagged as "not constructive" if a different flagging reason would have applied too. $\endgroup$ Feb 12, 2014 at 16:25
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    $\begingroup$ You seem to try and take the StackOverflow approach in this community which is very different from SO. $\endgroup$
    – Asaf Karagila Mod
    Feb 12, 2014 at 17:12
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    $\begingroup$ @Michael: Would you be willing to compromise on "not constructible (from a real number)" instead? :-) $\endgroup$
    – Asaf Karagila Mod
    Feb 12, 2014 at 17:12
  • $\begingroup$ @AsafKaragila In fact when I asked this question I was only familiar with Phys.SE. I intentionally asked this question to see how moderation works on this site. This is the best community website on internet that I have seen ever. I myself believe in <<If it ain't broke, don't fix it>>. Sorry for the huge delay in my response - I wasn't active here at that time. $\endgroup$
    – user103816
    May 4, 2014 at 8:46
  • $\begingroup$ I obviously cannot speak for even a significant part of the Math.SE community, but IMHO in vaguely similar other matters the following kind of thinking won a lot of support: We refuse to define the exact limits of what is appropriate and what is not, because A) we cannot possible foresee all the future forms of inappropriateness, and B) having an official rule may (will?) lead to some members skirting such a rule and being jerks while technically not in violation. $\endgroup$ May 19, 2014 at 6:32
  • $\begingroup$ @JyrkiLahtonen I guess all of us agree with Willie's answer given below. It seems to be a very nice and friendly policy. It can be made faq. The moderation on this site is very good. New users from other sites are not familiar with this. Even I wasn't so I flagged some unnecessary flags. Making it a faq would make users not to raise unnecessary flags. $\endgroup$
    – user103816
    May 19, 2014 at 6:43

1 Answer 1


There's no written policy (until now, I guess), and each mod has his or her quirks (so the discussion below is guaranteed to apply only if the handling moderator is yours truly). While you asked about "not constructive", let me be more ambitious and answer in the greatest generality. Before saying anything else, let me first say this:

Moderation on each site is different

... and reflects the evolving culture of the community that uses that website. What applies to StackOverflow does not necessarily apply to Math.SE. And there were many moderation decisions made 3 years ago that, nowadays, probably would have turned out differently.

For a new user who is familiar with other websites in the StackExchange family, a first look at the moderation on this website may give the feeling that the moderation is very lax. Indeed, compare to some of the other more tightly-run SE sites, a lot of what happens on MSE may be described as organised anarchy. Some indications:

  • We are generally a lot more permissive about what constitutes on-topic questions here than elsewhere.
  • Meta often ending in a bit of a free-for-all.
  • Users constantly bickering with each other about "problem statement questions" in the comments.
  • And of course, the persistence of comments. (See below; the only other site I know with even higher reluctance to remove comments is MathOverflow. Yes, it has something to do with mathematicians and/or academics.)

Why do we clean up comments?

Comments are by design ephemeral: their edit history is not open to anyone but the developers, and deleted comments can only be seen by diamond moderators. One may argue that the SE philosophy is such that cleaning up of comments (through their deletion and flagging) is encouraged. But we don't believe that comments should be deleted for the sake of deleting comments.

The general (there are some local variations) rule of thumb applied on the main website (by myself and many other mods; meta works somewhat differently) is that:

We delete a comment if and only if its presence does more harm than good.

In particular:

We do not delete a comment if its presence does neither harm nor good.

In mathematical language:

For "non-constructive", we treat the term "constructive" as a closed condition ("in the French sense").

In what cases would the presence of a comment do harm?

  • The comment can be hate speech or just offensive.
  • The comment can be commercial spam.
  • The presence of a comment can be misleading or confusing to the readers. (For example, comments answering a question which is only presented in a now-deleted comment; comments about a mistake in a previous version of a post.)
  • The presence of comments can lead to off-topic discussions. (Keep meta discussions to meta, please.)
  • Certain comments, their presence in themselves doing neither good nor harm, can be harmful in the larger scheme of things by making it harder to follow other, actually useful, comment discussions.
  • Extremely long comment threads can outlive their usefulness; especially the case where a third party reader will not glean anything useful by unfolding the comments and following the whole discussion.
  • Comment threads can become heated, which may lead to full-out flame-wars and overall unpleasantness.

This list is by no means complete, but should give you an idea what moderator(s) look for when they decide whether to act on a comment flag.

Why were your flags declined?

While I wasn't the handling moderator, I can easily guess the reasons.

  • A "thank you" comment from the OP is basic human politeness. In the case where the existing comment thread is not very long, its presence basically does no harm.
  • The degree of chattiness that each moderator tolerates is different. In my opinion a couple comments by two users familiar with each other about each other's answers is hardly distracting or harmful when they are not obscuring "more important things".
  • While downvoters are not required to explain their downvotes, the standing policy of this site has always been that users may ask about the downvotes. They are just expected not to complain if they don't receive an answer.
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    $\begingroup$ I won't even attempt to write something as comprehensive as Willie's answer, but I will note that in looking at some statistics, I am likely the ♦-mod most willing to delete comments when they are flagged. Even this being so, I will almost never delete a "Thank-you" comment from the OP of a question to an answerer. ("+1", "WTG!", etc. comments from third parties are a different matter entirely.) $\endgroup$
    – user642796
    Feb 12, 2014 at 15:52
  • $\begingroup$ While implementation may differ, I fully agree with this post. $\endgroup$ Feb 12, 2014 at 16:24
  • $\begingroup$ This is a good overview of how I feel about comments. However, because comments are ephemeral, I will ask that comments which answer a question be made into answers and comments which are essential to a post be incorporated into the post. $\endgroup$
    – robjohn Mod
    Feb 12, 2014 at 17:02
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    $\begingroup$ Humans do chat in the line of work. Teachers make little jokes to lighten the atmosphere during the progress of lectures. This is a global community and we all live in different time zones. There seems to be fairly strong opposition to PMs here so, without them, comments are a time independent avenue for the odd human aside. I for one see no harm in them - we're not robots - not quite yet anyway. $\endgroup$ Feb 13, 2014 at 2:05
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    $\begingroup$ I agree with Geoff Pointer - comments are a key part of the site, and they bring out the human and interpersonal aspect. I think they also help to bridge the gap between "the paper and the talk"; an answer is somewhat formal, but comments can be used for more informal communication. This process is not something to be brushed under the rug - that is an unfortunate habit that is already prevalent in mathematics papers. $\endgroup$ Feb 13, 2014 at 2:42
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    $\begingroup$ @Geoff: What if we are robots? And all the evidence we "find" to the contrary is just a defense mechanism introduced by our programming and our creators? We don't blood, we just collectively imagine that we do, so we won't find out the truth! Scary thoughts... $\endgroup$
    – Asaf Karagila Mod
    Apr 2, 2014 at 17:00
  • $\begingroup$ @AsafKaragila "We're not robots." It's just a turn of phrase. If we were programmed, in the way you describe, then we would still require informal comments, otherwise, it might give the game away. But, I'm just joking. What about you? You don't seriously worry about stuff like that do you, really? If so, you do know about the skeptic's infinite regression problem and how much of your life you can pointlessly waste worrying about it? An infinite chain of programmers? At the very least, some kind of Occam's razor leads me to not look beyond our own existence. $\endgroup$ Apr 2, 2014 at 22:23
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    $\begingroup$ @Geoff: I am almost offended that you replied seriously. $\endgroup$
    – Asaf Karagila Mod
    Apr 2, 2014 at 22:40
  • $\begingroup$ @AsafKaragila You shouldn't take my comments personally. I don't know you from Adam. I have no idea what you think about anything really. You could be a robot for all I know. My comment is not aimed at you, because I don't know who you are, instead it's posed as a series of questions, not a series of assumptions. I'm offended that you're offended. What I do know is that many humans would fail the Turing test. And you obviously don't get my sense of humour. $\endgroup$ Apr 2, 2014 at 23:12
  • $\begingroup$ @Geoff:. I didn't say I am offended. Note the "almost" that's hiding there before that word. $\endgroup$
    – Asaf Karagila Mod
    Apr 2, 2014 at 23:19
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    $\begingroup$ Amen to this very nice answer. If only moderators on Physics SE would be half as nice and reasonable as the ones guiding Math SE and MathOverflow. The strong (SE) political and rather unacademic overmoderation made me practically leave that site. I am always astonished about how Maths SE manages to keep up its nice collegial and rather academic community feeling despite many past violent collisions with the SE Overlords I have read about. Keep up the good work and nice community. $\endgroup$
    – Dilaton
    Apr 2, 2014 at 23:45
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    $\begingroup$ @AsafKaragila My apologies. Correction: I'm almost offended that you're almost offended. We might almost be friends in the almost real world. Descartes had it wrong, anyway. I think, therefore I almost probably am. But, am what? $\endgroup$ Apr 3, 2014 at 0:07
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    $\begingroup$ @Geoff: I am (almost offended that you are almost offended that I am almost offended)$^{\omega_1}$. Now, let's get on with it... :-) $\endgroup$
    – Asaf Karagila Mod
    Apr 3, 2014 at 0:10

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