わけがないThere is no way
わけがない categorically rejects an idea as impossible or unthinkable from the speaker’s point of view. It is stronger and more confident than simply saying that something is unlikely.
What the speaker is rejecting
The part before the construction is the idea being rejected. The speaker may be denying a claim, accusation, interpretation, or apparent possibility. The point is not merely that the event has a low chance of happening: the speaker confidently treats it as out of the question.
彼がそんな話を信じるわけがない。
There is no way he would believe a story like that.
AnalyzePolite and conversational forms
These forms express the same categorical denial; what changes is their conversational style and politeness.
Past and negative ideas
A completed past or negative plain form can come before the construction. Keep that form intact, then add the denial.
あれほど説明したのだから、彼が知らなかったわけがない。
After all that explanation, there is no way he did not know.
Analyze知らなかった is the negative past idea being rejected.
Three nearby expressions
はずがない often brings an expectation based on known facts or logic to the foreground, while わけがない commonly sounds like the speaker’s categorical rejection. This is a useful tendency, not an absolute dividing line, and the two can overlap. わけにはいかない is fundamentally different: the action may be possible, but circumstances or social expectations make doing it unacceptable. っこない is more colloquial and is especially natural for confident predictions that someone cannot or will not perform an action.
この列車が各駅停車なら、十時までに着くはずがない。
If this train is a local, it cannot be expected to arrive by ten.
AnalyzeThis neighboring form rejects an expectation by referring to a known fact about the train.
More examples
あの慎重な人が、確認せずに決めたわけがない。
There is no way that cautious person decided without checking.
Analyze一度も練習していないのに、優勝できるわけがない。
There is no way you can win without having practiced even once.
Analyzeこの小さな箱に荷物が全部入るわけがない。
There is no way all the luggage will fit in this small box.
Analyze彼女が理由もなく怒るわけがありません。
There is no way she would get angry for no reason.
Analyzeこんな大きな問題が一日で解決するわけない。
There’s no way such a big problem will be solved in one day.
Analyze説明を一度読んだだけで、すべて理解できるわけがない。
There is no way anyone could understand everything after reading the explanation only once.
Analyze彼が犯人なわけがない。事件の時間には海外にいた。
There is no way he is the culprit. He was abroad at the time of the incident.
Analyze長年の問題が、そんな簡単なわけがない。
A long-standing problem cannot possibly be that simple.
Analyze