InstaGov/issues
Retroactive Content Changing
There is a potential problem where a user edits a question or answer so as to change the sense of it after some consequences (answers to a question, ratings of an answer) have already been registered.
The rigorous way to prevent this would be for vote to be tied to a particular revision of a question/answer. I am hoping that community monitoring will turn out to be more effective at preventing malicious content-modification than revision control would be -- e.g. users can vote on whether an edit reflects a significant change to a item's meaning, and whether it should have been posted as a separate item. That will also take some development, but won't be as much of a usability obstacle as making everyone vote again every time there's a minor tweak to an answer's content.
In any case, I'm taking the approach of developing the simplest system that's usable, but trying to anticipate problems and having ideas fleshed out for dealing with them if they happen.