Expressing Reason & Cause
Learning Objectives
- Review the subjective reason particle 〜から.
- Learn the objective and polite reason conjunction 〜ので.
- Use the て-form to express emotional reactions and light causes.
- Use 〜ために to express formal cause and purpose.
In N5, you learned that 〜から means “because.” However, if you apologize to your boss using 〜から, it might sound entirely too defensive or subjective! Japanese has different grammar points for subjective reasons, objective facts, emotional triggers, and formal written causes. Let’s learn which one to use when.
1. Subjective Reason: 〜から
You already know 〜から. It attaches directly to the end of a sentence (or to the plain form).
〜から places the focus heavily on the speaker’s personal opinion, will, or subjective judgment. Because it is subjective, you naturally use it when the result (the second half of the sentence) contains a command, request, or personal intention.
危ないから、触らないでください。
abunai kara, sawaranaide kudasai.
Because it is dangerous, please do not touch it.
明日テストがあるから、勉強します。
ashita tesuto ga aru kara, benkyou shimasu.
Because there's a test tomorrow, I will study.
2. Objective/Polite Reason: 〜ので
〜ので is the polite, objective counterpart to 〜から. It presents the reason as a natural sequence of events or a universally understood fact. Because it sounds more objective, it is much softer and is the preferred way to state reasons in business, formal requests, and apologies.
Formation Rules:
- Verbs & i-Adjectives: Plain form + ので
- Na-Adjectives & Nouns: Add
なbefore ので (e.g., 静かなので、雨なので)
お腹が痛いので、帰らせていただきます。
onaka ga itai node, kaerasete itadakimasu.
Since my stomach hurts, I will (humbly) go home.
バスが遅れたので、遅刻しました。
basu ga okureta node, chikoku shimashita.
Since the bus was delayed, I was late.
[!WARNING] Because
〜のでis an objective statement of fact, you generally cannot follow it with a strong personal command like〜しなさい(do this). Use〜からfor commands!
3. Light Cause/Emotional Trigger: て-form / で
You can use the て-form of a verb or adjective (or で for nouns) to indicate a light, natural cause.
This is exclusively used when the result (Sentence 2) is:
- An uncontrollable emotion (surprised, happy, glad).
- A potential verb in the negative (cannot do something because…).
- A natural state (it broke, it died).
You cannot use the て-form reason if the second sentence contains a volitional action, intention, or request!
ニュースを聞いて、びっくりしました。
nyuusu o kiite, bikkuri shimashita.
I heard the news and (because of it) was surprised.
難しくて、わかりません。
muzukashikute, wakarimasen.
It is difficult, so I don't understand.
事故で、電車が止まっています。
jiko de, densha ga tomatte imasu.
Because of an accident, the train is stopped.
4. Formal Written Cause & Purpose: 〜ために
〜ために has two distinct meanings depending on how it’s used.
A. Cause (Because of/Due to): When followed by a negative result or an objective state, it means “due to.” This is very formal and used in news reports and writing.
- Formation: Plain Verb + ために / Noun + のために / Na-Adj + なために
B. Purpose (In order to): When the clause before ために is a volitional action you can control, and the clause after it is an action you are doing to achieve it, it means “in order to.”
雪のために、飛行機が遅れました。
yuki no tame ni, hikouki ga okuremashita.
Due to the snow, the airplane was delayed. (Cause)
家を買うために、貯金しています。
ie o kau tame ni, chokin shite imasu.
In order to buy a house, I am saving money. (Purpose)
Contextual Dialogue
Let’s see how Tanaka and Suzuki navigate apologizing and explaining reasons at work.
鈴木さん、遅いですね。会議が始まっているから、急いでください。
Suzuki-san, osoi desu ne. Kaigi ga hajimatte iru kara, isoide kudasai.
Suzuki-san, you are late. Because the meeting has started, please hurry.
本当にすみません。事故で電車が止まってしまったんです。
Hontou ni sumimasen. Jiko de densha ga tomatte shimatta n desu.
I am really sorry. Because of an accident, the train stopped.
事故ですか。それなら仕方がないですね。課長が怒っていたので、謝ったほうがいいですよ。
Jiko desu ka. Sore nara shikata ga nai desu ne. Kachou ga okotte ita node, ayamatta hou ga ii desu yo.
An accident? Then it couldn't be helped. Since the section manager was angry, you should apologize.
はい。課長に謝るために、今から席へ行ってきます。
Hai. Kachou ni ayamaru tame ni, ima kara seki e itte kimasu.
Yes. In order to apologize to the manager, I will go to his desk now.
わかりました。理由を聞いて、安心しました。
Wakarimashita. Riyuu o kiite, anshin shimashita.
Okay. Hearing the reason, I am relieved.
Chapter Summary
- 1〜から emphasizes subjective reason and pairs well with personal commands/intentions.
- 2〜ので presents an objective sequence of events and is polite (used for apologies).
- 3The て-form expresses light causation, usually resulting in emotions, natural states, or inability to do something.
- 4〜ために means 'in order to' (purpose) but can also mean 'due to' (formal cause) depending on context.
Knowledge Check
Test your understanding of showing reason and cause!
Quiz
Which pattern is BEST to politely explain to your boss why you are sick and need to go home?