I think that a very large fraction of the time, when a possibility appears to be coherent and well formed, it may turn out not to be upon more careful examination. I would see the subject matter of "fairies" as "that which causes us to talk about fairies", the subject matter of "dogs" as "that which causes us to talk about dogs", and the subject matter of "morality" as "that which causes us to talk about morality". All three are interesting.