That's why: 〜わけだ
plain form (な-adj + な / Noun + な・という) + わけだ
plain form (な-adj + な / Noun + な・という) + わけだ: that's why, no wonder, that means. A logical conclusion drawn from a known fact (それで, どうりで, つまり).
In short
〜わけだ presents a logical conclusion: from a fact or an explanation, you understand why things are as they are. “That's why, no wonder, that means”. Often introduced by それで, だから or どうりで.
- 三年も日本に住んでいたなら、日本語が上手なわけだ。さんねんもにほんにすんでいたなら、にほんごがじょうずなわけだ。If he's lived in Japan for three years, no wonder his Japanese is good.
- 「今日は祝日ですよ。」「ああ、それで道が混んでいるわけですね。」「きょうはしゅくじつですよ。」「ああ、それでみちがこんでいるわけですね。」“Today's a public holiday.” “Ah, that's why the roads are so busy.”
- 窓が開いていた。どうりで寒いわけだ。まどがあいていた。どうりでさむいわけだ。The window was open. No wonder it's cold.
- 彼はどういうわけか、今日は来なかった。かれはどういうわけか、きょうはこなかった。For some reason, he didn't come today.
The basics
わけ means “reason, logic”. 〜わけだ indicates that something follows logically from what you've just learned or said: everything makes sense, the pieces of the puzzle fit together. English says “that's why”, “no wonder”, “that means”.
It's used very often at the moment you realise: you discover a cause and draw the conclusion.
The window was open. No wonder it's cold.
- verb
- other
- adjective
- grammatical form
- 毎日歩いているから、元気なわけだ。まいにちあるいているから、げんきなわけだ。He walks every day: no wonder he's so fit.
- 京都の人だったのか。それで京都に詳しいわけだ。きょうとのひとだったのか。それできょうとにくわしいわけだ。Oh, he's from Kyoto! That's why he knows the city so well.
How to form it
わけ is a noun. Verbs and い-adjectives in the plain form; な-adjectives with な; nouns with な or という (休みなわけだ, 休みというわけだ). Politely: わけです.
| Before わけだ | Form | Example |
|---|---|---|
| verb | plain form | 混んでいるわけだ |
| い-adjective | plain form | 寒いわけだ |
| な-adjective | 〜な | 上手なわけだ |
| noun | 〜な / 〜という | 休みなわけだ、休みというわけだ |
- つまり、来週は会議がないというわけですね。つまり、らいしゅうはかいぎがないというわけですね。In other words, there's no meeting next week, is that right?
Three uses
The explained observation: それで / どうりで + 〜わけだ (“that's why, no wonder”). Rephrasing: つまり + 〜というわけだ (“in other words, it comes down to”). The expression どういうわけか: “for some reason”.
- 一日に二時間勉強すれば、一週間で十四時間勉強するわけだ。いちにちににじかんべんきょうすれば、いっしゅうかんでじゅうよじかんべんきょうするわけだ。If I study two hours a day, that makes fourteen hours a week.
- どういうわけか、最近よく眠れない。どういうわけか、さいきんよくねむれない。For some reason, I haven't been sleeping well lately.
わけだ, はずだ, のだ
はずだ (N4) makes a prediction before checking: 彼はもう着いたはずだ (“he should have arrived”). わけだ draws a conclusion from a known fact: 窓が開いていた。寒いわけだ. のだ (N4) gives an explanation, without the idea of “everything fits”.
| Form | Idea | Example |
|---|---|---|
| 〜はずだ | expectation, prediction | 彼はもう着いたはずだ |
| 〜わけだ | logical conclusion, it makes sense | それで寒いわけだ |
| 〜のだ | explanation | 風邪をひいたんです |
Common mistakes
- Translating it word for word as “it's a reason”: render わけだ as “that's why”, “no wonder”, “that means”.
- Mixing it up with はずだ: はずだ = what should be (prediction); わけだ = what makes sense once you know the cause.
- Forgetting な after a な-adjective: 上手なわけだ, not “上手わけだ”.
8 exercises on this point
Particles to choose, sentences to put back in order, translations: marked straight away, then reviewed at the right time. This JLPT N3 point is on the Nara Line (Studies and knowledge) of the Kyoto lines.