I understand the grammatical usage of these words, but I don't understand why they (roughly) mean "cannot" and "can".
For example, if we write them with kanji, we get 兼ねる and 兼ねない. According to jisho.org, that kanji has the following meanings: "concurrently, and, beforehand, in advance". None of these meanings directly corresponds to the meaning of "cannot" and "can", so why would that kanji be used?
Here's the research so far:
- There might be a relationship with 悲しい: http://gogen-allguide.com/ka/kanashii.html
- There might be a relationship with 嫌: https://ja.wiktionary.org/wiki/%E5%85%BC#%E6%B4%BE%E7%94%9F%E5%AD%97
- There might be a relationship with 予ぬ: https://ja.wiktionary.org/wiki/%E3%81%8B%E3%81%AC
I'm trying to find an intuitive way to understand how this usage came to be, to better "feel" the intention of the word. Any help appreciated!