Coming up with new kinds of pragmatics is sort of fun, but it's hard to tell when an idea is incompatible with how people work psychologically.
For instance, what are the limits or universals around asking and answering questions?
I had an idea the other day for a particle that can be used to refuse to answer a question without giving an excuse such as
I don't know, but that also isn't rude.
I can think of a couple of non-specific ways of refusing to answer a question in English, but they're all rude or combative.
1. None of your business. 2. Don't ask me that. 3. What a great question. 4. No comment.
The idea behind the question-refusal particle is that it shifts some of the social burden of asking appropriate questions from the asker to the recipient. The other part of the idea is that, in the larger pragmatics/[fake culture] surrounding this language, asking a question that the recipient cannot decline to answer is considered inherently hostile. Therefore, most questions in an ordinary conversation would not come with an expectation of being answered merely considered.
Let's assume with a generic verb-initial language with a few case suffixes for the purposes of this question
y/n.ques INT-see-FIN-REALIS story-ACC Did you see the movie (lit: story)? NONRESPONSE No comment.
Is it unrealistic to design such a language and then insist by fiat that the various ways of explicitly not-answering a question are not rude?