Prompted by a comment thread, I was curious if my understanding of the semantic differences between
is actually correct or just a delusion.
(か？ and のか？ further complicate things so I've left them out to keep everyone sane.)
I conjured up a bunch of example scenarios and have tried to categorize them and how each different type of ending works.
When you are asking for something to be confirmed because you didn't hear it or it was surprising...
医者［○？ ｘなの？ ○ですか？ ｘなんですか？］
なの？ and なんですか？ seem like they are asking a redundant question to me. I would not be surprised if this was me making a mistake, though.
Referring to immediate states of things
There's a certain class of 形容動詞 which seem to behave differently, for example:
ダメ ［○？ ○なの？ ○ですか？ ○なんですか？］
大丈夫［○？ ○なの？ ○ですか？ ○なんですか？］
These 形容動詞 seem to accept simply ？.
However, ones which don't refer to the immediate states of things don't accept ？ nearly as easily, e.g.:
きれい［ｘ？ ○なの？ ○ですか？ ○なんですか？］
上手 ［ｘ？ ○なの？ ○ですか？ ○なんですか？］
(I can't seem to think of any 名詞 which allow just ？ aside from in the confirmation usage.)
Sometimes, you follow a statement up with a question asking regarding some inference you've made.
彼は医者［ｘ？ ○なの？ △ですか？ ○なんですか？］
I think the latter three all work, but なの？ and なんですか？ seem to "flow" a tiny bit better to me than ですか？.
誰［○？ ○なの？ ○ですか？ ○なんですか？］
彼氏は医者［ｘ？ ○なの？ ○ですか？ ○なんですか？］
There are other things like rhetorical questions which use none of these endings, so they are not included unless there ends up being a good reason.
Comparing the endings
So, sometimes multiple things work equally well. Are there differences in nuance?
- There's the obvious difference in politeness between the non-です and です versions.
- I really do not see a difference between ですか？ and なんですか？ in the cases I have them both marked as ○. This is unlike the non-question case: 「彼氏は医者です。」「彼氏は医者なんです。」, where the latter sounds more like you're making a stance on something or using the sentence as justification something.
- When both ？ and なの？ are possible, なの？ seems more childish to me.
So, how much have I gotten wrong here? Are there other types of scenarios worth considering? (Sorry for the long blogging question.)
I'm totally open to an answer which completely ignores my analysis and gives a radically different one.