I wonder what the community policy is respecting question edits that change the meaning, and existing answers to earlier version of the question. I looked around a bit but only managed to find several hints that meaning-changing edits to questions are generally a no-no. None of the posts addressed the problem what to do with existing answers. I'd be happy for a reference therefore.
I occasionally read past questions and answers across StackExchange, but it never occurred to me to delve into the edit history of posts and their timestamps to find out which answer pertains to which version of the question. Never fully dawned on me that if an answer does not seem to answer the question, it may be because the question has been edited substantially.
Never, that is to say, until I saw it happen. The question Is there a single, opposite word to “alibi”? has been edited many times. While the first few versions seemed to me to be mainly about criminal acts and incriminating evidence for such, the later versions seemed to be mainly about presence at a party and evidence one's been there.
Several users, me included, posted answers that addressed various edits of the post. The modified meaning of the question probably rendered some answers a bit bizzare. (I am not implying that my own answer was invalidated in this manner. Rather, because I posted an answer, I had the opportunity to watch the evolution of the question and the various answers to it.)
Regarding my own post, of course I might delete it (but that would feel as if I have changed my mind about it, which I have not) or edit it (but then I might not even notice the edit to the question, and if I did, I might not feel up to answering the new question).
It occurred to me whether it is useful to maintain a different policy towards edits of one's own questions, and edits of other people's questions. Once the question is posted, people start thinking about it and posting their answers. The effort put into this activity is diminished if the meaning to the question is changed. Therefore, it might be useful if edits by OP to an already posted question were subject to approval of community members, in a manner similar to edits to other users' posts. (I probably do not fathom the intricacies of the editing mechanism, so this may be totally off the hook.)
Is there a general way to deal with the situation?
Added, based on answers and comments: I think I need to step back from the strong claim I made about the "alibi" post that inspired my question here at meta. Several people pointed out to me that they perceive the subsequent edits of that post as clarifying, not meaning changing. While I cannot agree, I realize I may be completely wrong about the word "alibi" (which, to me, indeed strongly connotes a crime), and I would like to apologize for unnecessarily focusing on the specific example. The question stands in general.