訳がない
There is no way, There is no reason, It is impossible, Cannot be
Structure
［な］Adjective + な + わけがない
［い］Adjective + わけがない
(1) Verb［た］
Explanation
A particularly strong way to use the noun わけ is in the phrase わけがない. This expression is most often translated as 'it's impossible that (A)' or 'there's no way that (A)'. Recalling from other lessons that わけ is conceptually similar to 'reason' or the English 'so', this phrase can be understood emphatically as 'there's SO no reason for (A) to be true'. Grammatically, this pattern joins わけ with the case marking particle が and the い-Adjective ない.
わけがない is used after verbs and adjectives in their attributive form (plain/dictionary form).
- この量の宿題、一日で終わるわけがないよ。There's no way I can finish this much homework in a single day.
- 彼女はプロのデザイナーだよ。デザインが悪い訳がないじゃない。She's a professional designer, you know. There's no way her design is bad!
- 駅から歩いて30分もかかる。そんな場所が便利なわけがない。It takes 30 minutes to walk from the station. A place like that can't possibly be convenient.
Caution
In comparison to わけではない, the expression わけがない is far more forceful, asserting the absolute impossibility of something. The difference can be seen as 'it's not necessarily the case that (A)' (for わけではない), versus 'there is absolutely NO WAY that (A) is the case' (for わけがない).
- ケーキを食べないけど、甘いものが嫌いなわけではない。I'm not eating cake, but it's not that I dislike sweet things.
- 昨日テニスを始めたばかりだから、上手なわけがない。He just started playing tennis yesterday, so there's no way he's good at it.
'It's not that (A) is the case' clarifies that while a situation might appear to be (A), this is an incorrect assumption. On the other hand, 'there is no way that (A) is the case' completely dismisses the possibility of (A) being true whatsoever.
Examples
あんなにたくさん食べたのだから、おなかが空いているわけがない。
After eating that much, there's no way he's still hungry.
五つ星ホテルが安いわけがない。
There is no way a five-star hotel would be cheap.
この部屋がきれいなわけがないでしょう。ゴミだらけですよ。
There's no way this room is clean. It's covered in trash!
一度も勉強していないのに、試験に合格できるわけがない。
Having not studied at all, it's impossible that they could pass the exam.
毎日練習しているんだから、試合に負けるわけがない。
They practice every day, so there is no way they will lose the match.
彼は正直な人だから、人をだますわけがない。
He is an honest person, so it is impossible that he would deceive people.
電気が消えているから、誰かいるわけがない。
The lights are off, so there is no way anyone is there.
このラーメンがこんなに美味しいわけがない。
It can't be that this ramen is this delicious.
あんなに高いものを子供が買えるわけがない。
There is no way a child could afford something that expensive.
地図があるのだから、道に迷うわけがない。
Since you have a map, there's no reason you would get lost.
初心者がいきなりプロに勝てるわけがない。
It is impossible for a beginner to suddenly beat a professional.
あんなに元気だったのに、病気なわけがない。
He was so energetic, so there's no way he is sick.