How to say "affirmation" in Japanese

• 肯定こうていJLPT N2approx.Common
  noun, suru verb, transitive verbAffirmation as the positive counterpart of negation — accepting or endorsing something, as in logic or psychology. Use this when 'affirmation' means a positive stance rather than a forceful spoken declaration.
  ディベートとは肯定こうてい側がわと否定ひてい側がわで交かわされる知的ちてきゲームである。↗

  Debate is an academic game between the affirmative and the negative.
• 断言だんげんJLPT N1approx.Common
  noun, suru verb, transitive verbCovers 'affirmation' as a firm, confident declaration that something is definitely the case. Use it when the emphasis is on the speaker's conviction, not on positivity.
  私は彼かれが潔白けっぱくだと断言だんげんした。↗

  I affirmed that he was innocent.
• 確認かくにんJLPT N3approx.Common
  noun, suru verb, transitive verbSeldom the word you want for 'affirmation': it really means confirmation or verification — checking that something is correct or has been properly arranged. Reach for it only when the English could be replaced by 'confirmation'.
  予約よやくは確認かくにんされています。↗

  I have a confirmed reservation.

Use 肯定 for affirmation as the positive counterpart of negation, 断言 for a confident, emphatic assertion, and 確認 only where English 'confirmation' would fit — it rarely renders 'affirmation' itself.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 肯定こうていaffirmation
• 断言だんげんassertion
• 確認かくにんconfirmation
• アファメーションaffirmation
• 言い切りいいきりaffirmation