That, and for some questions (i.e. nuances), a personal opinion is much more relevant to the asker than some random slop explanation. In this case I wanted to know which word construct in Turkish comes closes to the English “[ so and so ] is [ whatever ], isn’t it?” vs. “[ so and so ] is not [ whatever ], is it?” - Because Turkish has “isn’t it?” (değil mi? = not so?) but it doesn’t have “is it?”, mostly because “to be” is used much different in the language.

A google result wouldn’t help me at all - the pure grammar answer is “there’s no form of ‘is it’ to be coupled with a negative assumption/assertion”. But does a language construct exist to transport the nuance of “the speaker assumes that something is NOT [soandso], and wants to ask confirmation” vs. the speaker assuming that something IS [soandso], and asking for confirmation.

I still don’t know the answer, but it appears this nuance can’t be expressed in Turkish without describing around it in a longer sentence.