I am still confused about the nuances of different だ/ではない sentence endings, even after years of studying Japanese. Here are all possible combinations I can think of and my own understanding:
猫だ – [It] is a cat.
猫か – A cat?
猫だろう – [It] is probably a cat. OR Isn’t it a cat?
猫だろうか – [It] is probably a cat? (uncertain if it is true)
猫ではない – [It] is not a cat.
猫ではないか – Isn’t it a cat? (certain it is a cat; affirmation) Note: Sometimes, it is same as 猫なのではないか
猫ではないだろう – I don’t think it is a cat. (it is probably not cat)
猫ではないだろうか – Isn’t it probably a cat. (less certain compared to 猫だろう)
猫ではないのだ – [It] is *not* a cat.
猫ではないのか – Isn’t it a cat? (certain it is not a cat)
猫ではないのだろう – I don’t think it is a cat. (bit stronger than 猫ではないだろう)
猫ではないのだろうか – Is it because it is not a cat? OR I am not sure if it is a cat and I feel uneasy about it.
猫なのだ – [It] is a cat!
猫なのか – Bit stronger (perhaps demanding) version of 猫か
猫なのだろう – It is probably because it is a cat. OR It is probably that it is a cat.
猫なのだろうか – I wonder if it is a cat.
猫なのではない – It is not that it is a cat.
猫なのではないか – Isn’t it that it is a cat? (has a nuance of bit weaker affirmation than 猫ではないか) OR It is probably a cat. (猫なのではないだろうか)
猫なのではないだろう – It is probably not that it is a cat.
猫なのではないだろうか – It is probably a cat. OR Isn’t it probably that it is a cat?
猫なのではないのだ
猫なのではないのか
猫なのではないのだろう
猫なのではないのだろうか
I am not sure if my understanding is correct and I hope somebody can verify all or some of these for me. Also, I have no clue how to understand the last four:
“`
猫なのではないのだ
猫なのではないのか
猫なのではないのだろう
猫なのではないのだろうか
“`
I don’t think I’ve seen/heard these patterns before.
Also, I think it would help if anyone knows any research paper that gives comprehensive overview of the differences.
by Boot-Licker-Asshole