〜ものだ（当然 / 忠告・義務） mono da
〜ものだ（当然 / 忠告・義務）（mono da）means “one should... / it's natural that... (general truth / advice)”. States a general truth, common sense, or social norm — what naturally is or what one ought to do. Formation: V-る ／ V-ない ＋ ものだ ／ Aい ＋ ものだ ／ Aな ＋ な ＋ ものだ
one should... / it's natural that... (general truth / advice)
N2Formation
V-る ／ V-ない ＋ ものだ ／ Aい ＋ ものだ ／ Aな ＋ な ＋ ものだ
Explanation
States a general truth, common sense, or social norm — what naturally is or what one ought to do. As advice it says 'you should (not) ...' based on common sense, not a specific order. The negative form V-ない＋ものだ means 'one should not...'. It speaks of how things are/should be in general, not about one particular person's single action.
Examples
Note
Use for general norms, not to scold one person's single act (for that use 〜べきだ or 〜なさい). Distinguish from the emotive/reminiscent 〜ものだ.
FAQ
〜ものだ（当然 / 忠告・義務） — what does it mean and how is it used?
one should... / it's natural that... (general truth / advice). States a general truth, common sense, or social norm — what naturally is or what one ought to do. As advice it says 'you should (not) ...' based on common sense, not a specific order. The negative form V-ない＋ものだ means 'one should not...'. It speaks of how things are/should be in general, not about one particular person's single action.
〜ものだ（当然 / 忠告・義務） — how do you form it?
V-る ／ V-ない ＋ ものだ ／ Aい ＋ ものだ ／ Aな ＋ な ＋ ものだ
〜ものだ（当然 / 忠告・義務） — any usage notes?
Use for general norms, not to scold one person's single act (for that use 〜べきだ or 〜なさい). Distinguish from the emotive/reminiscent 〜ものだ.