Japanese rarely states things as bald facts. A stance layer at the very end of the sentence signals how sure you are and where your information came from. Mastering this is much of the gap between sounding like a textbook and sounding like a person. These all attach to plain form, with small copula tweaks.
でしょう / だろう — "probably"
A confident-ish guess. でしょう is polite, だろう plain. Attaches to a plain clause or a bare noun (no だ: 明日は雨でしょう). With rising intonation, でしょう？ seeks agreement — softer and less certain than ね.
かもしれない — "might"
Lower confidence than でしょう — a real maybe. Casual short form: かも. Plain clause / noun + かもしれない.
| Japanese | Reading | Meaning |
|---|---|---|
| 彼は来ないかもしれない | kare wa konai kamoshirenai | he might not come |
| 雨が降るでしょう | ame ga furu deshō | it'll probably rain |
はず — "should / is supposed to"
An expectation that follows logically from what you know — not a desire and not advice (for "you should do," see Wanting & Having To). 〜はずだ; the negative 〜はずがない means "there's no way / it can't be." Attaches like a noun modifier: plain form + はず, na-adj + な, noun + の.
| Japanese | Reading | Meaning |
|---|---|---|
| 彼はもう着いたはずだ | kare wa mō tsuita hazu da | he should have arrived by now |
| そんなはずがない | sonna hazu ga nai | that can't be right |
The two 〜そう — don't conflate
This is the single most common confusion in this whole area.
- Appearance — ます-stem / adjective stem + そう = "looks like / seems about to," based on what you see right now. 雨が降りそう ("looks like rain"), おいしそう ("looks tasty"). Irregular: いい→よさそう, ない→なさそう.
- Hearsay — a complete plain clause + そうだ = "I hear that / they say." 雨が降るそうだ ("I hear it'll rain").
The tell: a bare stem before そう is appearance; a full plain clause before そう is hearsay.
〜らしい and 〜ようだ / 〜みたい — "it seems"
らしい presents a conclusion drawn from outside information — reasonable inference, a step removed from your own eyes. ようだ / みたい is your own inferential read from what you observe — more personal and a bit more confident. ようだ is formal/written; みたい is casual/spoken. Both also do resemblance ("like ~"): 〜のようだ / 〜みたい.
| Japanese | Reading | Meaning |
|---|---|---|
| 彼は忙しいらしい | kare wa isogashii rashii | he's apparently busy (I gather) |
| 誰かいるようだ | dareka iru yō da | it seems someone is here (I sense) |
| 子供みたいだ | kodomo mitai da | (he)'s like a child |
A rough ladder
| Form | Confidence | Where it comes from |
|---|---|---|
| かもしれない | low | a guess |
| でしょう・だろう | medium | a guess |
| はず | high | logical expectation |
| 〜そう (stem) | — | what you see right now |
| ようだ・みたい | — | your own inference |
| らしい・〜そうだ | — | information you received |