A constant stream of duplicates arrives on Stack Overflow. Most duplicates are answered, only a few get closed as duplicate. I suspect most duplicate closes go to controversial questions. It takes effort to mark a duplicate, so the question has to annoy at least five people enough to get closed as duplicate.

Besides being somewhat arbitrary:

  • Closing offends the original poster
  • Sometimes a question that's only a duplicate at first glance is closed
  • A duplicate close basically locks an answer at an old state of knowledge. If a new solution came out, it could be added to the old question, but it would be dead at the bottom of the answer list

So instead of "voting to close", how about this friendly approach instead?

  • As an alternative to adding an answer, anyone can add a duplicate suggestion
  • A duplicate suggestion can be upvoted or downvoted like other answers
  • If the OP marks the duplicate as answer, the question is closed and merged with the original

Some advantages:

  • It ensures the duplicate is really a duplicate in the eyes of the poster
  • It does not offend the OP
  • It rewards people for finding duplicates that actually help the OP

3 Answers 3


I am very, very much in favour of making duplicate suggestions vote-able because it encourages looking for duplicates, something the current system doesn't do. I feel the need for this grows on SO every day.

I'm opposed to leaving the choice up to the OP, though. The OP is rarely the most competent person to judge whether a question is a duplicate or not. If you ask a question, your natural human tendency is going to be to fight for that question to stay open when there's the tiniest shred of doubt whether it's a duplicate or not.

The 5-person voting system should stay in place. The quality of the SO data pool is more important than avoiding the possibility of offending a user. If a question was falsely closed as duplicate, it can be reopened again. Seeing as dupe questions rarely get reopened, I would support a lowering of the reopen threshold to 3 to make reopening easier.


This makes a faulty assumption that all OPs are responsive and even look at these things. This is especially the case with a myriad of duplicate questions that are migrated to Meta, where the original author doesn't bother to come register here. This also assumes that all OPs are responsible and will understand when an appropriate duplicate arises. Like you said, some people get offended at the concept of having their questions closed, so even when it fundamentally is a duplicate, these people will use every possible content difference ("I asked about posting images, that post is only talking about posting screenshots!") to keep their question open.

The author of a question is not necessarily the authority on whether that question is a duplicate or not. That does not mean that the community is always right and they are always wrong - it is perfectly acceptable to appeal closings, which is why we have the reopen process in the first place. But the best way to get your question reopened is to be civil. If you're civil about it and can clearly explain why a question is not a duplicate, you stand a chance to convince people that your question deserves to be reopened.

Restricting the approval vote of duplicates to the OP and moderators, noting that duplicates are in fact one of the largest problems we have, would be rather damaging to the system. Yes, we might reduce the number of closings of questions that would need to be reopened, but you also will reduce the number of closings of questions that need to be closed. And there are a lot more of the latter.

I'm not saying that the OP is always going to be of bad judgment here, but that being the author of a question does not grant the OP any better judgment than the rest of us. We're not faultless either, which is why it isn't a one-person process for the community vote. If the OP (or anyone else, for that matter) can explain the case convincingly, and there are many good cases out there, the question can end up reopened. Since the vote-to-close as a duplicate generates an auto-comment identifying the vote, it's even possible to halt the incoming votes, and if you're convincing enough even the people who originally voted to close will vote to reopen if it does unfortunately get closed. Remember that the community can disagree with a closing proposal just the same as they can disagree with reopening (and speaking from experience, it is beyond amusing to have a question that should be closed as a duplicate and have it left open).

  • I've been checking the closed list lately, and the thing that stands out is that almost no poster acts in bad faith. The same cannot be said of close voters, who scare away newbies and often choose bogus reasons to close questions that are not to their taste. F.e. stackoverflow.com/questions/3159816/how-to-optmize-code-closed
    – Andomar
    Jul 3, 2010 at 9:53

I suspect most duplicate closes go to controversial questions.

I suspect that most duplicate closes occur on

  • What's the difference between ++i and i++?
  • How do I write a new language?
  • How do I solve [circular dependency problem] in FooLang?
  • Why does every keep using Foo and Bar?
  • What is the ?: operator and how does it work?
  • ...

and other perfectly legitimate questions that every program encounters at some point in their career plus

  • recommend a project
  • recommend a language
  • recommend a book
  • recommend a college
  • ...

and other chatty topics (which again are in everyone's purview). I mean, come on, we only have 750k questions on the site...

Most duplicates are answered, only a few get closed as duplicate.

It's not as bad as "only a few", but as long as we keep the incentives mixed up, this is going to be a problem, and it will prevent us from consistently achieving canonical pairings of questions with sets of answers.

But here is the thing: your suggest doesn't help with this. Not even a little bit because the incentive remains for potential posters to ask duplicates, not find where their question has already been answered. And for people reading the question the incentive remains to answer questions rather than to point out the existence of a duplicates with good answers.

  • Another list of commonly duplicated questions is being continually built over here.
    – Grace Note StaffMod
    Jul 2, 2010 at 16:39

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