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JLPT N2Cause & Effect

～ことだから— Knowing Them, Surely…

Used to make a confident prediction based on the well-known character or nature of a specific person (or group). It means 'because it's ~ (whom we know so well), surely…' The speaker draws a conclusion precisely because of shared knowledge about that person's typical behavior.

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Pro lessonUNIT 24 · CAUSE & EFFECT

Structure · 形

[Noun (person) + の] + ことだから

Examples · 例文

  • 真面目な彼のことだから、きっと約束を守るでしょう。

    Majime na kare no koto da kara, kitto yakusoku o mamoru deshou.

    Being the diligent person he is, he'll surely keep his promise.

    彼のことだから + prediction based on his known character

  • 田中さんのことだから、もう準備は終わっているはずだ。

    Tanaka-san no koto da kara, mou junbi wa owatte iru hazu da.

    Knowing Tanaka, the preparations are surely already done.

    田中さんのことだから draws a confident guess from Tanaka's usual reliability

  • あの子のことだから、また遅刻するに違いない。

    Ano ko no koto da kara, mata chikoku suru ni chigainai.

    Knowing that kid, he's bound to be late again.

    ことだから + negative prediction based on the child's habitual behavior

Usage notes · 注意

  • The noun is almost always a specific person (or organization) the speaker knows well.
  • Usually followed by a guess/prediction (でしょう, はず, に違いない, きっと).
  • The prediction is justified by that person's known personality or habits.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ～ことだから is tested against.

vs～のことだ

Plain のことだ just means 'about ~'; ことだから specifically uses knowledge of someone's character to justify a prediction.

vs～だから

だから gives a general reason; ことだから adds the nuance 'because it's this particular person we know, we can predict their behavior.'

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