About 3 months ago, I asked a question about some specific claims on controlled crying techniques.
The question was tightly focused, referenced very specific notable claims, and was highly voted.
A few weeks later, the question attracted the notice of the poster of a related question. After discussing it, the two of us agreed that our questions were focusing on distinctly different aspects of the subject (i.e. "signal value and parent-child communication" vs. "generally harmful"). This agreement was largely made due to the fact that none of the answers to the "is it harmful" question in any way addressed the question I had asked, even though they were relevant and quality answers to the other question.
Over time, my question continued to garner votes, but received no answers, aside from one that was found to reference a single source that was most likely not valid for the question. I offered a bounty on the question, and even contacted the origin of the claims to see if I could obtain an answer direct from the source (my request was ignored).
I believe that the answer to my question may very well be "no, there is no scientific support for those claims", but the absence of evidence does not indicate proof. I don't believe this makes the question invalid; rather I think it makes the question exceptionally valid.
It does, however, demonstrate the contrast between the two questions, as one has received valid answers, and the other may be only answerable by the absence of evidence supporting it. Per a previous meta discussion, an accepted sign of duplicate questions seems to be duplicate answers. That is not the case here.
Yesterday my question was closed as a duplicate of the other. The reason given was that they both cover the same ground, and that they needed to be merged.
My question is: what exactly defines when two questions cover the same ground? We have a number of questions on record that are asking about different aspects of the same thing, which is exactly what these two questions are doing. Do not this question and this question cover the same ground, even though they were both determined distinct enough to leave open? I notice Sklivvz has mentioned merging those two questions, even though community consensus seemed to be that they were not the same question, and it looks like the more recent version was reopened?
Here is another example of two questions covering the same ground. Again, it seems that Sklivvz closed one, and the community elected to reopen (after significant improvements). However, even after significant improvements, they seem no more dissimilar than the two controlled crying questions.
Rather than focusing on my specific question, I would like to encourage discussion for a way to define how we can tell objectively if two questions are too similar.
Are two questions exploring distinct aspects of claims on a general concept duplicates?
If the claim is "doing x is bad because it causes a, b, and c", is "Is doing x bad?" the same as "Does doing x cause a?", and is that the same as "Does doing x cause b?"? What if doing x causes a and c, but not b? Does this impact how the questions should be worded? If asking "Is doing x bad?" precludes asking "Does x cause a?", should we discourage such general questions, and instead encourage focus on specific aspects of the claims? Or do we just hope that the answers are good enough to address all aspects of the claimed impact?
How about distinct questions on specific topics? Is "Does snake sweat dissolve the ink off of U.S. dollar bills?" distinct enough from "Does snake sweat help blisters heal?", or does the fact that both cover the ground of the reputed properties of snake sweat make them duplicate?