NYELVÉSZ

If I get this right, the interjection proves that Japanese verbs form an open class: one can easily create a new verb by adding a suffix. Hungarian verbs are just like that: borrowed verbs must be suffixed with -z or -l. Thus in both languages verbs are not a closed class in the sense that new items can be easily added, but they are in the sense that there are formal constraints on what a verb can look like (this is not normally referred to as a closed class, though). My impression is that the author of the quote mistook these two senses.

Well, it seems to be acceptable for me.



It also seems correct in most of the cases, but depends on what "the core of a language" means.



I can imagine different open/closed classes - i.e. the class of Mongolian and Turkic auxiliary verbs may be considered as open (at least not closed at all, similarly to Hungarian verbal prefixes), but that of English is rather closed.



I have no glue how Japanese pronouns work, but I'm curious about it.

And there is one more strange thing for me: "in Japanese [...] verbs are closed class" - I don't agree with this and its justification, I think there is some kind of misunderstanding, and the author got wrong. I hope somebody more familiar with Japanese can enlighten me.

Have you come across the Wikipedia page for "closed class"? Do you think it is correct? Do you think that a class that can be expanded through derivation, compounding, etc. qualifies as an "open class" just for that matter? Do you agree that a closed class somehow belongs to "the core of a language"? And, most importantly, do you agree that it varies from one language to the other what the open classes are and, in particular, that pronouns in Japanese constitute an open class???