Thomas Dalton wrote:
I {{fact}}-tagged a statement which I believed to be true but for which I couldn't find a citation - in a BLP, as it happens - and found it reverted with the edit summary "(x) not being related to (y) does not need a citation!"!!! I despair...
Put it back. I think the standard guideline is that only statements which nobody would question can be uncited ("the sky is blue" being the standard, although not very good, example) - and quite a few people would like citations for those anyway. The fact that you've added a {{fact}} tag shows that it is questioned, so does need a citation. {{fact}} tags should only be removed if you are removing the statement, adding a citation or if there is already a citation given.
Sometimes the citation IS already given, but not in that exact spot. Where an entire paragraph or group of paragraphs is taken from a standard source in the subject it should not be necessary to reference every detail of that passage, and it should be sufficient to state that a citation applies to the entire range.
Negative statements are trickier because hard evidence that something did _not_ happen usually cannot exist. The implicit message when we say that something did not happen is that we have no evidence that it did. Perhaps that requires a convention about negative statements. Attributing a claim that something did not happen, or showing why it was impossible for it to happen would remain a stronger statement.
Ec