I'm trying to logically grasp why い-adjectives switch to the ~く form in order to form a negative.
痛い (is painful)
痛くない (is not painful)
I understand ない to be an adjective.
い adjectives cannot modify other adjectives. However, い adjectives have an "adverbial" ~く form that can. From that perspective, it seems to be very logical that adjectives assume the ~く form in order to modify ない. (painful-is not)
Though even that's a bit confusing since it feels more natural to me to think of ない as modifying what precedes it...
Am I thinking about this correctly? I'm wondering how this is understood from the Japanese perspective.