Translation guide
The English word 'supposing' is used to introduce a hypothetical situation or assumption, often in conditional clauses. In Japanese, this is expressed through various conditional forms and phrases, not a single direct translation.
To say 'if we suppose that...' or 'assuming that...', often at the beginning of a sentence or clause.
A common pattern for presenting a hypothetical scenario. 'もし' emphasizes the supposition, and 'としたら' means 'if we assume'. The '…' is replaced by a clause in plain form.
もし彼が来なかったとしたら、どうする？
Supposing he doesn't come, what will you do?
Supposing it rains tomorrow, the game will be canceled.
A more formal or written expression meaning 'assuming that...'. Used in logical or mathematical contexts.
Xが5だと仮定すると、Yは10になる。
Supposing X is 5, Y becomes 10.
Similar to 'としたら', but slightly more formal. Often used in written Japanese.
彼が犯人だとすれば、動機は何だろう。
Supposing he is the culprit, what would be the motive?
Used to concede a point or explore a possibility, often in debate or discussion.
Means 'even supposing that...'. It concedes a hypothetical situation but implies it doesn't change the main point.
仮に彼の言うことが本当だとしても、許せない。
Supposing what he says is true, I still can't forgive him.
Formal version of 'even supposing'. Common in academic or technical discussions.
その理論が正しいと仮定しても、実用化は難しい。
Even supposing the theory is correct, practical application is difficult.
Posing a hypothetical question, often to explore possibilities or consequences.
A very common conversational pattern. 'もし' is optional but adds emphasis. 'どうする？' means 'what would you do?'.
もし宝くじが当たったらどうする？
Supposing you won the lottery, what would you do?
A shorter, casual way to say 'what if...?'. Often used among friends.
明日地球が滅びるとしたらどう？
Supposing the world ends tomorrow, what then?
There is no single Japanese word that directly corresponds to 'supposing'. Using a dictionary form like '仮定して' alone is unnatural. Always use a conditional structure like 〜としたら or 〜と仮定すると.
✕ 彼が来ないと仮定して、私たちは出発した。
Supposing he wouldn't come, we left. (unnatural)
◯ 彼が来ないものとして、私たちは出発した。
Assuming he wouldn't come, we left.
All three mean 'supposing/assuming'. としたら is most common in speech. とすれば is slightly more formal and often written. と仮定すると is explicitly 'assuming' and used in logical/mathematical contexts.
All three mean 'supposing/assuming'. としたら is most common in speech. とすれば is slightly more formal and often written. と仮定すると is explicitly 'assuming' and used in logical/mathematical contexts.