modality N3 common casualpolitewritten
ものだ — general truth / the way things ought to be
ものだ
Builds on もの
Meaning
① general-truth: ~ is just how it is / tends to be ~ — states a general truth or the inherent nature of things
② should: one should ~ / it's proper to ~ — states a social norm or how people are expected to behave
Key sentence
① general-truth
赤ちゃんはよく泣くものだ。
Babies cry a lot — that's just how they are.
② should
約束は守るものだ。
You should keep your promises.
Formation
| Attaches to | Form | Example |
|---|---|---|
| Verb / い-adjective (plain form) | Plain form + ものだ | 泣く → 泣くものだ / 守る → 守るものだ |
| な-adjective / Noun | な-adj + な + ものだ | 便利 → 便利なものだ |
Examples
① general-truth
年を取ると、昔のことを思い出すものだ。
As you get older, you naturally find yourself remembering the past.
人は誰でもいつかは死ぬものだ。
Everyone dies someday — it's the way of things.
② should
目上の人には敬語を使うものだ。
One ought to use polite language with one's superiors.
人の悪口を言うものではない。
You shouldn't speak ill of others.
Easily confused with
〜べきだ べきだ states an obligation for a specific act in a specific situation (今行くべきだ = 'you should go now'). ものだ in its 'should' sense states a broad social norm true of everyone (約束は守るものだ = 'one keeps one's promises'). 〜はずだ はずだ is a logical expectation drawn from specific evidence ('it should be the case that ~'). ものだ states a general truth or social norm, not a deduction about a particular situation.
Notes
- An exclamatory use also exists: 時間が経つのは早いものだ ('how fast time goes!'), expressing deep feeling about a general truth. For looking back on a past habit ('we used to ~'), use the past form たものだ.
See ものだ in real sentences
Jengo shows ものだ the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Intermediate Japanese Grammar.