Why do causal subordinate clauses ending in -から take だ as a means to connect nouns and な adjectives (e.g. 日本人だから), whereas causal subordinate clauses ending in -ので take な (e.g. 日本人なので)?

I read that だ derives from て+ある, whereas な derives from に+ある, but why would one causal conjunction require で, whereas another one requires に?

Just trying to make sense of it all…

Thank you!


1 Answer 1


This explanation is tautological but I just have to say it's because から follows a terminal form, which of the copula is だ while の is a kind of noun, which needs an attributive form to be modified, which of the copula is な.

Their etymology has nothing to do with this issue.

  • I think the OP wants to know why there are two forms though... that's the question.
    – Leebo
    Jul 23, 2018 at 14:15
  • 1
    @Leebo That's because many verbs originally had two forms, which later got merged into one except the copula.
    – user4092
    Jul 24, 2018 at 3:30
  • That actually kinda clears it up… Thank you!
    – Pregunto
    Jul 24, 2018 at 7:57

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