Despite the little notice in the comments section telling us that comments along the lines of 'thank you' aren't welcome because they don't move the discussion forward mathematically, I have always made a point of trying to thank other users when they elucidate something for me or otherwise help me out.

Recently, I had a 'thank you' comment on an answer to a question of mine get deleted; I have an educated guess as to who deleted it and why, and no real qualms with the deletion in this instance, but it made me realize that the moderation staff might be taking a harder line stance regarding professionalism. This is understandable, but I am curious what the community here feels should be prioritized: professionalism or decorum?

These things aren't diametrically opposed to one-another; any successful professional environment will naturally have some version of 'politeness' built into its structure and decorous environments naturally engender professional pursuits (to some extent), but they aren't synonymous either.

I personally try to err on the side of decorum in any environment, but this could just be me being weird. What are some other community opinions?

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    $\begingroup$ In some cases, a single flag can trigger deletion of a 'thank you' comment. I don't know the content of your comment which was deleted, so I don't know if that is likely what to be what happened to your comment, but it is possible that no moderator was involved in its deletion. $\endgroup$ Apr 13 at 18:06
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    $\begingroup$ Ah, that seems like the kind of short comment that would trigger the auto-deletion mechanism. I commented mainly because you said, "it made me realize that the moderation staff might be taking a harder line stance regarding professionalism", but maybe you weren't observing any moderator actions, only the auto-deletion mechanism at work. $\endgroup$ Apr 13 at 18:15
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    $\begingroup$ @TheAmplitwist Indeed, you may be correct! I'm still curious to hear people's opinions on the subject in the title, but agree that the instigating event for me was likely automatic. $\endgroup$
    – Alec Rhea
    Apr 13 at 18:41
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    $\begingroup$ Similar auto-deletions are known to happen in posts that begin with certain salutations. $\endgroup$ Apr 13 at 20:16
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    $\begingroup$ I hadn't seen that comment flagged in the queue. In my experience, there are a few users who are more than happy to flag old comments (like, really old) as "no longer needed" that I'd rather leave, for the sake of keeping a record of discussion, to show people how friction can be dissipated in a good way, or more generally as a model of good behaviour (including pleasantries!). MO is not StackOverflow, but a largely academic site, and a bit of collegiality goes a long way in showing the good side of what is done here. Ideally in a way that counteracts negative perceptions about grumpy users. $\endgroup$
    – David Roberts Mod
    Apr 13 at 21:19
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    $\begingroup$ I very much agree with @David. It is sometimes the case that some users are more zealous than others about comments. And since the SE software is somehow rigged against certain types of comments, it may require just one flag to delete. But I think that all of us on the moderating team are very much in favour of keeping the pleasantries approach intact. This is a small community, at the end of the day, and we're all trying to be friendly as much as possible. Saying thank you is a good thing. $\endgroup$
    – Asaf Karagila Mod
    Apr 13 at 21:24
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    $\begingroup$ I've always felt that some the "rules" regarding comments were inherited from a very different usage on StackOverflow. Here, comments often have quite a bit of intellectual content, and I am opposed to deleting comments just because they are old. I also happen to agree with Alec that pleasanties in the comments are totally fine and should be welcomed. $\endgroup$ Apr 14 at 0:02
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    $\begingroup$ @LSpice Yes, only the greeting is removed (though I personally don't consider that to be bad). $\endgroup$ Apr 14 at 15:52
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    $\begingroup$ @TheAmplitwist, re, I did not mean to weigh in on whether greetings were themselves a good idea, only about whether stripping them out automatically is a good idea. I think, in general, non-overrideable regex-based modification may be safely said always to be sometimes wrong. As @‍GerryMyerson points out, for example, because of this limitation one cannot begin a post by referring to the mathematician Hi Jun Choe. $\endgroup$
    – LSpice
    Apr 14 at 16:49
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    $\begingroup$ @LSpice Ah, I see. I do agree that silently stripping away text or markup is bad UX design. This also happens when commenting @OP when there is no third participant in the comments under the original poster's post. On the other hand, I don't find the particular example you linked to be convincing, but I should probably take any further comments there, or to chat, to stay on-topic here. $\endgroup$ Apr 14 at 20:14
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    $\begingroup$ I think "thank you" is, by the dictionary definitions, an expression of gratitude (and also possibly of approval) -- for, say, an answer, a question, shared knowledge, etc. (rather than just a matter of decorum), and I do not see how such an expression can be in any conflict with professionalism. So, I fail to understand how such an expression can be considered less than desirable. $\endgroup$ Apr 16 at 2:54
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    $\begingroup$ @FedericoPoloni I think it would be complicated to use chat for this. You could invite a user to a chatroom (assuming they have a chat account), but that seems like a lot of effort to only leave a "thank you" comment. You can also find which users are currently pingable in a chatroom by looking at the autocomplete options offered when you type @ in the chat box. $\endgroup$ Apr 17 at 2:35
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    $\begingroup$ @AlecRhea I have tried to edit the title; feel free to edit and clarify if you think I have misinterpreted your intentions. $\endgroup$ Apr 17 at 8:42
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    $\begingroup$ Yeah, I noted that many my old posts now end with my comment saying "You are welcome" without any indication of anyone thanking me for anything :lol: Whoever executed the deletions (be it a human or a machine) definitely didn't try to apply any common sense to the procedure... $\endgroup$
    – fedja
    Apr 17 at 20:24
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    $\begingroup$ @FedericoPoloni That is fine; I'm always a fan of a good vs thread, but agree that this title is more relevant to the content of the post. I did want to highlight the delineation between professionalism and decorum as motivators for behavior, but I'm not trying to die on that hill haha. $\endgroup$
    – Alec Rhea
    Apr 18 at 11:07

2 Answers 2


I must say that I think having a small amount of "personality" adds value to a community. Giving and receiving acknowledgement is one of the most benign additions to conversation, and it's clearly separated from the more professional Q&A aspect of the site.

More generally, comments provide a social outlet for the less professional interactions. In a positive context, this is used to ask/receive clarifications. But even this provides a "social" interaction between two people, and positive/helpful such interactions encourage people to return. Even seeing secondhand a clarification-and-answer in comments or a "thanks" gives the appearance of a somewhat "warm" community.

Professionalism and formal conduct has its place, especially when trying to resolve knowledge questions, but I would caution that being overly strict or overly formal has detrimental effects to building a community. I have been involved with extremely formal online communities in the past, and the "drier" the community, the more likely I am to self-censor, and find myself engaging with the community (as a community, a collection of people) less and less over the years.

MO seems to get the balance right with some occasional off-topic comments allowed (thanks/acknowledgement), while still generally maintaining professionalism (e.g., comments rarely devolve into chat conversations).

Just because comments are ephemeral, here is a related example of what I think MO does right. It is my favorite comment chain on MO (about Heisenbert and Heisenernie), and I hope it remains forever. It was a serious answer with a simple typo that is unlikely to be confused with anyone, and it spawned a couple of silly comments that have remained for 10+ years now. It makes me think that all these serious math folks are maybe not so scary; they can sometimes laugh at their own mistakes (a typo), and perhaps the serious math moderators are not so overbearing.

This is not quite the same as the original question, but I think it's relevant. Allowing slightly off-topic and/or occasional off-topic comments such as thanks/acknowledgement add value to a community and should be allowed.


Back when I was more active moderating, I had noticed that there was one particular user who had not contributed much mathematically, but had flagged an incredible number of comments for deletion - well into the thousands. Most of them were relatively innocuous, like "thank you"s and such, but some were good fits for "no longer needed". I mostly rejected the unnecessary flags, but some other moderators may not have done so. The rate of flagging was never too bothersome, so I never bothered to make contact to ask why.


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