Should we pose questions that we know are difficult to answer? (But can be answered.)
For closing posts on the Stack Exchange network, the reasoning often is:
This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form.
Where is the line of what's reasonable in the case of a difficult problem?
Update: If a question wasn't clear, then of course, it cannot be answered without due clarification. A call for improvement is probably what the closing statement above is mostly aimed at — especially the part: "in its current form".
However, for example, "overly broad" can have different meanings. Modifying CBredlow's words below, it may be easier for one person to answer a question that another deems as overly broad; and vice versa. So "overly broad" can simply mean difficult for some.
A philosopher could approach questions differently than a scientist.
The same goes for "ambiguous" — the definition of the word when it comes to language-use is: "open to more than one interpretation". Something like that could be difficult to answer for some, but not for others.