Sometimes a user offers an Answer which can be proven false, but the proof doesn't fit in the comment box. Is there a best practice for pointing this out? (I'm explicitly not asking about differences of opinion or judgement, but things that are provably true or false in a mathematical sense.)

  1. Offering the proof in a different Answer to the same Question doesn't seem like appropriate use of the Answer feature.
  2. Breaking the proof into several comments is tedious and hard because the edit duration expires.
  3. Asking and Answering a new Question, and then posting a comment that links to the new post seems like the best option.

Have I missed a better alternative?

  • 7
    $\begingroup$ I'm reluctant to identify any "best practice," because it seems like the response ought to vary with the circumstances. Often you can offer a constructive answer and, in passing, demonstrate why an existing answer is incorrect. If you don't want to do that, your third option (use a new thread as a reference) works well. $\endgroup$
    – whuber Mod
    Jul 8, 2020 at 15:37
  • 4
    $\begingroup$ That's a good point, and it hadn't occurred to me because, in the specific case I have in mind, I don't know the answer to OP's question. So I'll work on writing a question and answer to show the claim is false. $\endgroup$
    – Sycorax Mod
    Jul 8, 2020 at 15:50
  • 8
    $\begingroup$ I'm frequently in a position of not knowing a good answer, but being able to recognize a bad (or wrong) one ;-). As a moderator I focus my comments on encouraging the poster to improve their answer. That doesn't usually require that I offer a definitive proof of incorrectness: it suffices to suggest the reasons for reconsidering the answer. Some people take this the wrong way, though, so take care... . $\endgroup$
    – whuber Mod
    Jul 8, 2020 at 19:00
  • 4
    $\begingroup$ Yeah, it's tricky to get the comment to read just right so that your meaning is clear and that the reader doesn't take it as an affront. But in the meantime, someone else has offered a concise comment that points out the deficiency, so I guess I'm off the hook for correcting this answer. $\endgroup$
    – Sycorax Mod
    Jul 8, 2020 at 19:06

2 Answers 2


Just so that this question has an answer:

  • One method is to post your own answer to the question. In passing, it can demonstrate that an alternative strategy is not correct.

  • If the answer to the question is not known, then asking and answering a question can be one method to provide a demonstration.

  • As always is the case with interacting with other users, it requires careful wording to provide constructive feedback which is not read as an affront. This can be tricky.

  • $\begingroup$ When an answer that has been accepted is has a negative number of votes and is "not even wrong," but its author starts trying to defend the indefensible when this is pointed out in several comments by different people, there comes a time when "not causing an affront" is rather beside the point. (There was a recent example of that on Engineering SE - but I'm not going to post a link to it. I would guess the answer was accepted because it was what the OP wanted to hear, not because he/she was able to evaluate the truth of it.) $\endgroup$
    – alephzero
    Jul 19, 2020 at 20:22
  • $\begingroup$ What's your desired outcome in that scenario? As you've said, the post already has a negative score, and a number of comments describing why it's wrong. It seems like the SE mechanisms are working correctly, so why would causing an affront be helpful? After all of this negative feedback, it seems unlikely that causing an affront will suddenly compel the Answerer to understand engineering better, and thereby write a better answer. $\endgroup$
    – Sycorax Mod
    Jul 19, 2020 at 20:54

I would probably go for one of these:

  • Ask clarifying questions.

    These should ideally lead to edits to the answer instead of comment replies.

    If the poster made unsupported claims or had a few missing (and impossible) steps in their argument, you can ask them to expand on that.

    This could give you a much smaller part to disagree with, in that you don't need to prove the entire counter-claim from scratch, but you can rather just point out the incorrect part of their justification for their claim.

    This also has the advantages that they may see the issue in their answer themselves or you may realise you were actually wrong without having to have been wrong.

    Of course this doesn't work so well if they don't actually reply.

  • Ask a new self-answered question addressing the issue.

    If the new question would be a stand-alone question that could also be useful to others, then this is indeed probably the best option.

  • Give a brief summary of why they're wrong and link to elsewhere.

    This is actually also what you'd be doing when posting a new question.

    If it isn't a common error and you can't find a reference that explains it well, you could always link to chat and explain it yourself there.


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