Today for the first time I read something about 意志動詞 and 無意志動詞 (I guess in English, volitional verbs and non-volitional verbs). Basically, verbs that can be done with intention and verbs that can’t be done with intention.
The main issue with the two categories is that when a verb is non-volitional, it can’t do any of the conjugations that have anything to do with intention.
For instance, できる is a non-volitional verb, so you cannot say 日本語を話すことができたい.
A grammatical way to express this idea is 日本語を話すことができるようになりたい.
I think that’s easy enough to understand. There are certain things that we just can’t describe as being volitional.
The tricky thing is when verbs can either be volitional or non-volitional depending on the subject.
A bed cannot have volition, so it cannot take the potential form of 入る.
But humans can perform the action of 入る as well, and we have wills, so it’s okay for us.
So, it’s a simple concept in some ways, but I had never seen it spelled out. I wonder if I ever gave inanimate objects volition without realizing it.