Over the last maybe 6 months or so (I haven't really been keeping track), I've noticed a number of questions either nominated for closure or actually closed with some variant of this custom close reason:
I'm voting to close this question as off-topic because it is based on a faulty presupposition.
sometimes with more info, sometimes not. Now, I haven't been following meta too closely lately, so I may have missed this discussion, but since when is this a valid close reason?
Science is based on presuppositions (we generally call them hypotheses), then attempting to provide an experimental basis for them, or disproving them. I go into an experiment with an idea in mind, then use the results to reevaluate my idea should they be different from what I expect.
I don't see anything wrong with someone asking a question based on faulty information (their own thinking, a conversation with a friend, a random website, whatever), as we can use the answers to show how their idea is incorrect, then provide data and references to show what the current state of the field is.
A recent example is here (I don't want to throw anyone under the bus, but I think a concrete example is necessary). A new user asked a question based on two incorrect assumptions - that a "neutral" allele should be present in 50% of the population, and that the condition being referred to doesn't have any negative selection pressures on it. Two answers were provided (one by me), the first one showing why a neutral polymorphism wouldn't necessarily be present in 50% of the population. The other one (mine) showed that the condition isn't really "neutral" at all, as there have been several medical conditions associated with the phenotype in question, one of which leads to infertility, which definitely would lead to negative selection.
Both answers helped address the OP's question, and showed why they were incorrect in their initial thinking. However, some time after both answers were posted, a user voted to close based on the "faulty presupposition" reason, and within nine hours, four other users agreed, and as of now the question is on hold. I have nominated the question for reopening, so we'll see where that goes, but in the meantime I would like to have a discussion on the merits of the faulty presupposition argument.