Anyone else get completely confused by these two? Nakatta being past negative for U endings and katta as past positive for I-adjectives? It’s the small details between similar tenses that keep tripping me up and stress me out!
I definitely remember the times where all the grammar basics felt like such a confusing mess to remember.
~ない is technically an auxiliary adjective. That’s why it changes in the same way as any other い-adjective.
So it’s not that past negative is ~なかった. Negative is ~ない and given that it operates in the same way as all fellow adjectives, it drops the final い and has かった added.
I don’t remember that one specifically tripping me up (and as mentioned the way to think of it is ない → なかった the same as i-adjectives), but one kinda similar thing that I definitely remember being confused by is how a command or request ending in な might mean “do X” or “DON’T do X.”
Turns out it’s because the “do X” version is なさい shortened, while the “DON’T do X” is just な appended directly to the る form of a verb, so the way to tell them apart is the form of the verb itself:
Don’t eat this.
… boy was I glad to learn about that after quite a bit of “wait, this one’s a positive request? I thought な meant a negative command??”
It’s all just about slowly learning what to look for…