More and more I see questions getting closed, or getting a lot of closed votes, when in my mind they are not exact duplicates. I'd like to avoid specific examples here, more interested in general philosophy rather than arguing about specific questions.
In my mind, an exact duplicate is just that. Not the exact wording of course, but the same question where the same answer applies. Not a similar question, or a subset of another question but effectively the same question. One that could easily be found by a search of the site and immediately recognized as duplicate.
As Jeff says
One thing I want to be clear about, though, is that duplication is not necessarily bad. Quite the contrary — some duplication is desirable. There’s often benefit to having multiple subtle variants of a question around, as people tend to ask and search using completely different words, and the better our coverage, the better odds people can find the answer they’re looking for. And isn’t that, really, the whole point of this exercise?
Furthermore, it’s OK for duplicate questions to have duplicate answers. While you could argue that the duplicate questions could all be merged into one question with a “master” set of answers, this is kind of irritating from the perspective of the user looking for an answer. Put yourself in their shoes. Instead of finding
Duplicate Question — Duplicate Answer
They have to deal with finding:
Duplicate Question — [closed as duplicate of Question] click here to see answers
"subtle variants of a question" doesn't sound like what we allow here - we seem to me to do is look for the slightest connection with another answer and flag it as "possible duplicate".
There are a few types of questions I often see getting a lot of close votes here lately:
Simple question (with a simple answer) where there is a more general question with longer, involved answers
Sure, the long involved answers will provide enough information, if absorbed, to answer the simple question, but that doesn't make them a duplicate. We should in fact encourage simple questions with simple answers. A recent example was someone asking if shutter speed and film speed were the same thing, related, or independent of each other. That got a lot of close votes as a duplicate of the epic "what is the exposure triangle" question. No one should have to try to read 16 paragraphs of information to get what is effectively a yes/no answer to a simple question.
As Joel says:
For example, if a user asks, “What does the IP address 220.127.116.11/24 mean?” it’s OK to close that as a duplicate of a more general question like “What do IP addresses of the form a.b.c.d/e mean?” But it’s not OK to close it as a duplicate of a twenty-seven page guide to netmasks. That’s the moral equivalent of saying “RTFM.”
So again, just because another answer (to a different question!) does include the answer to a simpler question, being a superset of the needed answer doesn't make it a duplicate.
Simple questions where there is a similar question
These are hard, and I know it's a gray area. But to me, most of these types of questions are often not duplicates, but are often flagged as such:
Compare lens A vs lens B (Canon) where there is already a Nikon question on the equivalent lenses. There are distinct differences between specific lenses of different manufacturers. The Canon 50mm 1.4 may have horribly slow AF, and the Nikon soft in the corners. Sure there are general principles if they're comparing a prime lens vs kit zoom, but the offerings do differ between brands, and if they are asking a specific question about Canon, I don't feel we have the right to force them to generalize their question if it's Canon they want information on.
"Compare lens A vs lens B", where there is already a "Compare lens A vs lens C". No comment, but this happens a lot. Should we allow every conceivable combination of lens shopping questions? No comment there either. But A vs B is clearly not A vs C.
"Is f/4 lens with IS or f/2.8 lens better for sports?" when there is an existing question "Is ... or ... better for travel?" (or wildlife or portraits...). Surely not a duplicate, as different genres of photography have different requirements. And this allows people who are more experienced in wildlife or portraits to write specific answers for those genres. Trying to lump everything together is I think the opposite of what we should be doing. If I search on Canon 70-200mm f/2.8 and see a number of questions about various genres, and comparing it to a variety of other lenses, I'd rather see all those questions and read through them, rather than have one general question which doesn't really address the specific angle I was after
There are similar questions, yes, and so-called “exact” duplicates do happen, but they are kind of rare in my experience. It’s far more common to have many subtle variations of a question.
"Subtle variations" again. So are we sometimes being overzealous about closing questions? I think so. I think it discourages new people having their questions closed, and I think having a smaller set of questions discourages people from adding more answers if there are already 6 answers, one accepted. If a new question allowed, with a slightly different slant, it gives other people the chance to add their experience, where it is more relevant than on the more general "duplicate".
Questions where a poorly worded question already exists
Here we can edit the original question to make it better but I think we should simply allow a new, better question.
I think we should use a higher bar for determining a question is a duplicate. And I think if you find a related question, it's valuable to add that in a comment, but mark it as "related" rather than "possible duplicate".