As I state in the question, is there a StackExchange (or BH.SE) policy about how to supplement a good and sufficient answer in a way that will add relevant information and depth of knowledge?

I have an example, an answer I posted to supplement one by Niobius.

I upvoted Niobius, and added my material. My guess is that there are several possible alternatives:

  1. Edit the existing answer (but in the case, it was substantial material and the original already long enough).
  2. Add as comment (but ... I doubt the comment field is long enough).
  3. Post as an additional answer, making the relationship of the answers clear (this was the route I took).
  4. Don't bother - a sufficient answer is sufficient (but is it complete?).

Any advice from mods or more experienced contributors? Thanks!

2 Answers 2


Good question. Our aim is to provide the best possible answers but you obviously don't want to upset another contributor and that is also good :)

Addressing your points in turn:

  1. This is a great thing to do up until the point you are making substantial changes to the original: in that case it isn't the best option.

  2. Comments are only really useful for tangential information of requests for additional information. They are problematic for content that in any way answers the question (they can't be down-voted or improved, and they don't leverage the SE system for reducing noise, whereby better answers tend to float to the top).

  3. This is a perfectly good option. Ideally the answer would be as self-contained as possible but you may want to find a balance between that and referencing the other answer. There is nothing wrong with quoting from the other answer verbatim if you add attribution. If you are at all worried about doing so, you can ask the other user if they mind with a comment: I think most folk would be glad to see their good work built on.

  4. If you'd like to see a question answered better or more fully, then I say 'go for it'. As long as you are enjoying making contributions and have the time and inclination, there is no 'etiquette' reason for holding back. In the end your improved answer might help many people (not just the OP) and even the other contributor.

  • Works for me - thanks! If there is discussion to be had, I would be interested to hear - but that's a helpful clarification, and reassurance.
    – Dɑvïd
    Commented Jan 16, 2014 at 14:54

I think that even a supplemental answer should be ... an answer. If it reads more as an extended comment, this is problematic (which is not the case with your example).

My preference is to link to the answer rather than referencing the user name of the poster (although this is not wrong, I am merely stating my opinion), because it helps others find it and prevents this site from looking like a forum rather than a Q&A site. The other reasons are:

  • Someone could edit or delete their answer. The dead link will at least serve as notice for a deleted answer, but if you didn't cite at least a portion of the answer and it is later removed and/or radically changed, the reader may not be able to follow your response.
  • The order of answers changes based on voting. Your (supplemental) answer might end up having more upvotes than the answer you are expanding on, and yours may even be accepted as the top answer. Will this confuse readers if your argument is not self-contained?
  • As nice as it would be for folks who find us on Google to read both your answer and the one you're supplementing, most won't. It is more helpful to the Internet at large to provide enough of a summary to ensure your reasoning can be followed if they only read your post. Perhaps they will only get one aspect of the explanation, but that is fine so long as it provides an answer.

On the other hand:

  • There is no point in duplicating existing content with which you agree. A quick one-or-two-sentence summary or representative citation is perfectly acceptable.
  • Adding more information than exists in current answers makes the Internet a better place. It is better to err on the side of providing a quality response than to withhold information because of the effort involved (hopefully merely citing the thesis statement or conclusion of the existing answer makes the bar low enough as to not dissuade you and others from posting supplemental answers).

So I would say go for it. Feel free to post supplemental answers. Just make sure they are indeed answers.1

1 Your current answer does an excellent job at being an actual answer, so it is fine as is. My only preference would be that you also link to Niobius' answer, not just reference it by his username alone. In addition to helping the site remain focused more as a Q&A site rather than a forum, Niobius could actually post more than one answer to a question (maybe because he wants to play devil's advocate). It's rare, but if this happens, how will readers know which of his answers you are referring to?

  • 3
    Thanks Daи - characteristically helpful, and sensible! I have tweaked my answer along the lines you suggest: it should now better function as an independent piece, while still pointing to the original answer. | Interesting about one user being able to provide two answers to the same question. I didn't realize that was possible, and it isn't on another Q&A site I participate on that uses Askbot and isn't part of the SE ecosystem.
    – Dɑvïd
    Commented Jan 17, 2014 at 7:58

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