The fact that this question needed to be raised, confirms the point that I have made earlier, that it is misguided to try to come up with some precise, exhaustive list of criteria for the closing reason that will replace the current show-research reason (and roughly correspond to the old general-reference reason), that could then be applied mechanically.
What, I think, we want to be able to close by using this reason, are the questions to which a generally competent, generally well educated, speaker of English (but without any specialised education or talents that would be relevant to the question), either knows the answer or would be able to find the answer in less than ten minutes, if given access to the Internet or a moderately-sized library. That includes the matters to which there are straightforward answers in general-purpose dictionaries, but it includes some other matters. For example, it includes the grammar of English as it is standardly taught to non-native speakers and in other forms of non-specialised education. The questions about, say, parts of speech should be closed if they merely seek an answer that will be marked as correct in an introductory English course, but left open if they are about the subtleties of the way in which CGEL classifies words.
Araucaria seems to argue that the questions of the former kind do not exist, and I find it hard to see how anybody could believe that. It is of course true that we can take a naive question from somebody taking an introductory English course and transform it into a different, sophisticated question calling for a complex answer, but when we do that we are not really responding to the question intended by the OP.
The regular contributors to this site, I believe, have a good intuitive understanding of what separates the two kinds of questions, but it is very difficult to formulate it precisely. The best thing would be, I think, not to try, but instead trust the contributors who have earned the closing privileges to responsibly exercise their judgment as to whether something is too obvious to be worthy of an answer on this site.
Most people who regularly exercise their closing privileged will, in any event, continue to follow their intuitive understanding of what is too basic, too obvious, too trivial to be on this site, regardless of what wording of the closing reason is adopted. They will just vote to close such questions and then click on some reason or other that seems to be the closest to what is on their minds, even if it is not very close. Not having a general 'this is too obvious' reason will then result in many closed question having closing banners that do not reflect the real reasons.
Incidentally, Aracuria's question on this page, considered on its own, says only that 'we expressly do not want questions relating to parts of speech or other grammatical or syntactic concerns to be closed as "answerable by a dictionary"', which is something that almost everybody would agree with, but leaves it entirely open whether some of these questions should be closed as something else, or that none of of them should be closed at all. It is only when we read his comments that it becomes clear that he is arguing for the latter position. Heartspring has, in answering the related question made the same point, that a dictionary-focused wording of the reason does not cover basic grammar, but argues for the former position, and is supported in that by Cerberus and a number of upvoters. It is potentially confusing to those who have been following the debate about changing the show-research reason that the concern about basic-grammar questions has now been pulled out to this, separate page. It would have been more productive if the discussion about Araucaria's arguments had continued as a part of the general discussion about the new wording of the closing reason, where support for and opposition to his arguments can be considered together with support for and opposition to Heartspring's and Cerberus' arguments.
