ては・
ては・では presents a possible or repeated situation as leading to an undesirable, dangerous, troublesome, or unacceptable result. It often corresponds to “if” or “when,” but the following clause must make the negative judgment clear.
How the condition works
The first clause names the situation being considered. The second clause then states why that situation would be a problem. Common continuations express difficulty, danger, failure, waste, excessive cost, or another clearly negative outcome.
Across different word types
Notice that the form changes with the word before it, while the unfavorable-result pattern remains the same.
ここで諦めては、これまでの努力が無駄になる。
If we give up here, all our effort so far will go to waste.
Analyze値段が高くては、学生には手が出しにくい。
If the price is high, students will have difficulty affording it.
Analyze説明が複雑では、初めての人には分かりにくい。
If the explanation is complicated, it will be hard for first-time users to understand.
Analyze責任者が不在では、今ここで決定するのは難しい。
If the person in charge is absent, it will be difficult to make a decision here and now.
AnalyzeOne event or a repeated pattern
The condition can be a one-time possibility, as in giving up at a crucial moment, or a repeated behavior whose consequences are predictably bad. The surrounding context tells you which reading is intended.
A repeated behavior
毎晩こんなに遅くまで起きていては、朝の授業に集中できない。
If you keep staying up this late every night, you will not be able to concentrate in morning class.
AnalyzeTwo important distinctions
ては・では is the wider unfavorable-condition pattern: many different negative judgments can follow it. By contrast, the direct prohibition ending てはいけない specifically tells someone that an action is not allowed. The conditional と can state a regular consequence neutrally, whereas the target construction highlights that the consequence is unwelcome.
More examples
同じミスを繰り返していては、信用を失う。
If you keep repeating the same mistake, you will lose people's trust.
Analyze準備が不十分では、期限までに完成できない。
If the preparations are inadequate, we will not be able to finish by the deadline.
Analyze黙って帰っては、みんなが心配するよ。
If you leave without saying anything, everyone will worry.
Analyze毎日外食では、食費がかかりすぎる。
If you eat out every day, you will spend too much on food.
Analyzeそんな態度じゃ、話し合いは進まないよ。
If you take that attitude, the discussion will not get anywhere.
Analyze資料を確認せずに提出しては、間違いを見落とすおそれがある。
If you submit the documents without checking them, there is a risk that you will overlook mistakes.
Analyze