JLPT N4 Lesson 4: Expressing Probability and Inference
Master six essential Japanese patterns for expressing probability, hearsay, and inference — かもしれない, でしょう/だろう, はずだ/はずがない, らしい, そうだ (two uses!), and ようだ — with a certainty-scale comparison table.
Overview
In natural Japanese communication, speakers rarely express certainty about everything. Instead, a rich set of grammatical patterns allows you to indicate how sure you are about information — whether you are guessing, reporting what you heard, drawing a logical conclusion, or inferring from visible evidence. At N4, you must master six such patterns: 〜かもしれない, 〜でしょう/だろう, 〜はずだ/はずがない, 〜らしい, 〜そうだ (two distinct meanings!), and 〜ようだ.
The most challenging aspect of this lesson is the fact that several of these patterns translate to similar English phrases ("it seems," "probably," "apparently") but have very different nuances in Japanese. The difference between them involves: (1) how certain you are, (2) whether the basis is hearsay or personal observation, (3) whether the conclusion is logical or visual, and (4) whether you are the speaker or reporting someone else's view. A full comparison table with a 0–100% certainty scale is included to help you keep these patterns distinct.
Learning Objectives
By the end of this lesson you can:
- Distinguish and correctly use all six inference/probability patterns in context.
- Recognize the two completely different meanings of 〜そうだ (appearance vs. hearsay).
- Choose the appropriate pattern based on certainty level and type of evidence.
- Avoid the most common mix-up: confusing 〜そうだ (appearance) with 〜そうだ (hearsay).
New Vocabulary
| Japanese | Reading | Romaji | English | Part of Speech |
|---|---|---|---|---|
| 多分 | たぶん | tabun | probably (50–70%) | Adverb |
| きっと | きっと | kitto | surely, certainly (80–90%) | Adverb |
| もしかしたら | もしかしたら | moshikashitara | perhaps, by any chance | Adverb |
| どうやら | どうやら | dōyara | it seems (from evidence) | Adverb |
| どうも | どうも | dōmo | somehow, it seems | Adverb |
| らしい | らしい | rashii | seems like, I heard, typical of | Auxiliary adj. |
| 噂 | うわさ | uwasa | rumor | Noun |
| 天気予報 | てんきよほう | tenkiyohō | weather forecast | Noun |
| 証拠 | しょうこ | shōko | evidence, proof | Noun |
| 当然 | とうぜん | tōzen | naturally, of course | Adverb/Na-adj |
| 確かに | たしかに | tashika ni | certainly, indeed | Adverb |
| 予定 | よてい | yotei | plan, schedule | Noun |
| 間違いなく | まちがいなく | machigainaku | without doubt | Adverb |
| 観察 | かんさつ | kansatsu | observation | Noun |
| 推測 | すいそく | suisoku | inference, conjecture | Noun |
Grammar Points
Full Comparison Table: 6 Inference Patterns
| Pattern | Certainty | Basis | Use with | Notes |
|---|---|---|---|---|
| 〜かもしれない | 30–50% | Guess / little evidence | Plain form + かもしれない | Pure possibility; speaker is uncertain |
| 〜でしょう/だろう | 60–80% | Reasoning / logical guess | Plain form + でしょう | でしょう = polite; だろう = plain/masculine |
| 〜はずだ | 80–90% | Logical expectation | Plain form + はずだ | "It should be…" based on known facts |
| 〜はずがない | 95%+ | Strong logical denial | Plain form + はずがない | "There's no way…" — strong rejection |
| 〜らしい | hearsay | Info heard from others | Plain form + らしい | "Apparently…" — secondhand info |
| 〜そうだ (appearance) | visual | Direct visual observation | Adj stem / verb stem + そうだ | "Looks like…" — what you see right now |
| 〜そうだ (hearsay) | hearsay | Reported information | Plain form + そうだ | "I heard that…" — from others |
| 〜ようだ | 70–80% | Speaker's indirect evidence | Plain form + ようだ | "It seems that…" — speaker's own inference |
1. 〜かもしれない (Might, Maybe — 30–50%)
Structure: [Plain form] + かもしれない (polite: かもしれません)
Explanation: Expresses a possibility the speaker cannot confirm. The speaker has some reason to think something might be the case, but is genuinely unsure. Often used with もしかしたら or もしかして.
Examples:
| Japanese | Reading | Romaji | English |
|---|---|---|---|
| 明日は雨が降るかもしれない。 | あしたはあめがふるかもしれない。 | Ashita wa ame ga furu kamoshirenai. | It might rain tomorrow. |
| 彼女はもう家に帰ったかもしれません。 | かのじょはもういえにかえったかもしれません。 | Kanojo wa mō ie ni kaetta kamoshiremasen. | She might have already gone home. |
| もしかしたら試験に合格できないかもしれない。 | もしかしたらしけんにごうかくできないかもしれない。 | Moshikashitara shiken ni gōkaku dekinai kamoshirenai. | Maybe I won't be able to pass the exam. |
| あの人、病気かもしれないね。 | あのひと、びょうきかもしれないね。 | Ano hito, byōki kamoshirenai ne. | That person might be sick, don't you think? |
Common mistake: ❌ 彼は来ないかもしれないです (redundant) → ✓ 彼は来ないかもしれません (Already polite with かもしれません; adding です is redundant)
2. 〜でしょう / 〜だろう (Probably — 60–80%)
Structure: [Plain form] + でしょう (polite) / だろう (plain/casual masculine)
Explanation: Expresses a reasonably confident prediction or assumption. でしょう is the polite form used in neutral speech and weather forecasts; だろう is the plain-form equivalent, more common in casual masculine speech or when the speaker is reasoning aloud. Both can be used with たぶん or きっと to reinforce certainty level.
Examples:
| Japanese | Reading | Romaji | English |
|---|---|---|---|
| 明日は晴れるでしょう。 | あしたははれるでしょう。 | Ashita wa hareru deshō. | It will probably be sunny tomorrow. |
| 彼はもう知っているだろう。 | かれはもうしっているだろう。 | Kare wa mō shitte iru darō. | He probably already knows. |
| きっと上手くいくでしょう。 | きっとうまくいくでしょう。 | Kitto umaku iku deshō. | It will surely go well. |
| たぶん田中さんは来ないでしょう。 | たぶんたなかさんはこないでしょう。 | Tabun Tanaka-san wa konai deshō. | Tanaka probably won't come. |
Common mistake: ❌ 明日は雨が降ると思いますでしょう → ✓ 明日は雨が降るでしょう (Don't stack と思う and でしょう; choose one)
3. 〜はずだ / 〜はずがない (Should Be / Can't Be — 80–95%)
Structure:
- [Plain form] + はずだ → logical expectation ("should/ought to be")
- [Plain form] + はずがない → logical impossibility ("there's no way")
Explanation: はずだ is based on prior knowledge or a logical conclusion from known facts. You know something should be a certain way because of what you already know. It is not a guess — it's a deduction. はずがない is its emphatic negative, meaning the speaker is certain something cannot be so, based on reason.
Examples:
| Japanese | Reading | Romaji | English |
|---|---|---|---|
| 田中さんは今日来るはずだ。 | たなかさんはきょうくるはずだ。 | Tanaka-san wa kyō kuru hazu da. | Tanaka should come today (I know he has plans to). |
| 鍵はここにあるはずなのに、ない。 | かぎはここにあるはずなのに、ない。 | Kagi wa koko ni aru hazu na no ni, nai. | The key should be here, but it's not. |
| 彼が嘘をつくはずがない。 | かれがうそをつくはずがない。 | Kare ga uso o tsuku hazu ga nai. | There's no way he would lie. |
| この問題は難しいはずがない。 | このもんだいはむずかしいはずがない。 | Kono mondai wa muzukashii hazu ga nai. | This problem can't be hard (I know it's simple). |
Common mistake: ❌ 彼は来るはずだかもしれない → ✓ 彼は来るかもしれない OR 彼は来るはずだ (はずだ already implies logical certainty; stacking with かもしれない is contradictory)
4. 〜らしい (Apparently / I Heard — Hearsay)
Structure: [Plain form] + らしい (verb/adj) / [Noun] + らしい
Explanation: 〜らしい has two distinct uses. First, hearsay: information obtained from external sources (rumors, news, what others told you). Second, typicality: "typical of" or "characteristic of" (e.g., 彼らしい = "very like him"). For N4, the hearsay use is primary. Unlike 〜そうだ (hearsay), 〜らしい often implies the speaker has gathered this from multiple sources or it has become general knowledge.
Examples:
| Japanese | Reading | Romaji | English |
|---|---|---|---|
| 田中さんは結婚するらしい。 | たなかさんはけっこんするらしい。 | Tanaka-san wa kekkon suru rashii. | Apparently Tanaka is getting married. |
| あの店は高いらしいよ。 | あのみせはたかいらしいよ。 | Ano mise wa takai rashii yo. | I hear that shop is expensive. |
| 彼女は日本語が上手らしい。 | かのじょはにほんごがじょうずらしい。 | Kanojo wa Nihongo ga jōzu rashii. | She's apparently good at Japanese. |
| 今日の試験は難しかったらしい。 | きょうのしけんはむずかしかったらしい。 | Kyō no shiken wa muzukashikatta rashii. | I hear today's exam was difficult. |
Common mistake: ❌ らしく見える (for visual observation) → ✓ ようだ / そうだ (appearance) (らしい = hearsay, not visual observation; for what you see, use ようだ or appearance-そうだ)
5. 〜そうだ — TWO COMPLETELY DIFFERENT USES
This is the most important distinction in this lesson. そうだ has two completely unrelated meanings depending on what comes before it.
Use A: Appearance (looks like) — stem form Structure: [い-adj stem] + そうだ / [な-adj stem] + そうだ / [verb stem] + そうだ
The speaker makes a visual observation right now — something looks a certain way to them.
Use B: Hearsay (I heard) — plain form Structure: [Plain form] + そうだ
The speaker reports information heard from someone else. The content of what was heard uses plain form.
| Japanese | Reading | Romaji | English | Use |
|---|---|---|---|---|
| このケーキ、美味しそう！ | このけーき、おいしそう！ | Kono kēki, oishisō! | This cake looks delicious! | Appearance (adj stem + そう) |
| 彼は疲れそうだ。 | かれはつかれそうだ。 | Kare wa tsuresō da. | He looks tired. | Appearance (verb stem + そう) |
| 雨が降りそうだ。 | あめがふりそうだ。 | Ame ga furisō da. | It looks like it's going to rain. | Appearance (verb stem + そう) |
| 田中さんは来ないそうだ。 | たなかさんはこないそうだ。 | Tanaka-san wa konai sō da. | I heard Tanaka won't come. | Hearsay (plain form + そうだ) |
| 天気予報によると、明日は晴れるそうです。 | てんきよほうによると、あしたははれるそうです。 | Tenkiyohō ni yoru to, ashita wa hareru sō desu. | According to the forecast, it will be sunny tomorrow. | Hearsay (plain form + そうだ) |
Critical note on negatives:
- 美味しくなさそう (doesn't look delicious) — appearance negative: くない → くなさそう
- 美味しくないそうだ (I heard it's not delicious) — hearsay negative: plain form くない + そうだ
Common mistake: ❌ このケーキは美味しいそうだ (using plain form for appearance) → ✓ このケーキは美味しそうだ (stem form) The full form 美味しい (not just 美味し) + そうだ = hearsay, not appearance.
6. 〜ようだ (It Seems — Speaker's Indirect Evidence)
Structure: [Plain form] + ようだ (polite: ようです) / [Noun] の + ようだ
Explanation: 〜ようだ expresses the speaker's inference based on indirect evidence they have personally gathered — what they can see, hear, or have pieced together. It is more formal than らしい and suggests a slightly more careful, observational inference. It often co-occurs with どうやら or どうも to emphasize that the speaker is piecing something together.
Examples:
| Japanese | Reading | Romaji | English |
|---|---|---|---|
| どうやら彼は怒っているようだ。 | どうやらかれはおこっているようだ。 | Dōyara kare wa okotte iru yō da. | It seems like he's angry (from what I can tell). |
| 鍵をなくしたようです。 | かぎをなくしたようです。 | Kagi o nakushita yō desu. | It seems I've lost my key. |
| 外は雨が降っているようですね。 | そとはあめがふっているようですね。 | Soto wa ame ga futte iru yō desu ne. | It seems to be raining outside. |
| あの人は日本人のようだ。 | あのひとはにほんじんのようだ。 | Ano hito wa Nihonjin no yō da. | That person seems to be Japanese. |
Common mistake: ❌ らしい and ようだ are completely interchangeable → NOT always true らしい = hearsay from others; ようだ = speaker's own inference. They overlap but are not the same.
Dialogues
Dialogue 1: Discussing a Classmate's Absence
Yui (Y) and Kenji (K) are talking before class.
| # | Japanese | Romaji | English |
|---|---|---|---|
| 1 | Y: あれ、今日も田中くんいないね。 | Are, kyō mo Tanaka-kun inai ne. | Hm, Tanaka's not here again today. |
| 2 | K: うん、風邪を引いているらしいよ。 | Un, kaze o hiite iru rashii yo. | Yeah, apparently he has a cold. |
| 3 | Y: そうなんだ。熱があるのかな。 | Sō na n da. Netsu ga aru no kana. | I see. I wonder if he has a fever. |
| 4 | K: 昨日、顔色が悪そうだったから、そうかもしれない。 | Kinō, kaoiro ga warusō datta kara, sō kamoshirenai. | His complexion looked bad yesterday, so it might be the case. |
| 5 | Y: 先生によると、来週の試験はとても難しいそうだよ。 | Sensei ni yoru to, raishū no shiken wa totemo muzukashii sō da yo. | According to the teacher, next week's test is apparently very hard. |
| 6 | K: それ知ってた。田中くん、大変そうだね。 | Sore shitteta. Tanaka-kun, taihen sō da ne. | I knew that. Looks like it'll be tough for Tanaka. |
| 7 | Y: 試験前に回復するはずだけど、心配だな。 | Shiken mae ni kaifuku suru hazu da kedo, shinpai da na. | He should recover before the exam, but I'm worried. |
| 8 | K: 友達に連絡してあげようか。 | Tomodachi ni renraku shite ageyō ka. | Shall we contact him? |
| 9 | Y: いいね。体調が悪いなら、ノートを貸してあげよう。 | Ii ne. Taichō ga warui nara, nōto o kashite ageyō. | Good idea. If he's not feeling well, let's lend him our notes. |
| 10 | K: どうやら今日は休むようだから、それがいいね。 | Dōyara kyō wa yasumu yō da kara, sore ga ii ne. | It seems like he's resting today, so that sounds good. |
Dialogue 2: Weather and Plans
Misa (M) and Taro (T) are discussing weekend plans.
| # | Japanese | Romaji | English |
|---|---|---|---|
| 1 | M: 週末、花見に行かない？ | Shūmatsu, hanami ni ikanai? | Want to go to hanami this weekend? |
| 2 | T: 行きたいけど、天気が心配。 | Ikitai kedo, tenki ga shinpai. | I want to but I'm worried about the weather. |
| 3 | M: 天気予報によると、土曜日は晴れるそうだよ。 | Tenkiyohō ni yoru to, doyōbi wa hareru sō da yo. | According to the forecast, it'll be sunny Saturday. |
| 4 | T: 本当？でも今の空、曇っているようだけど。 | Hontō? Demo ima no sora, kumotte iru yō da kedo. | Really? But the sky now seems cloudy. |
| 5 | M: 今は曇っていても、明日は晴れるはずだよ。 | Ima wa kumotte ite mo, ashita wa hareru hazu da yo. | Even if it's cloudy now, it should clear up tomorrow. |
| 6 | T: じゃあ、土曜日に行こうか。でも、念のために傘を持っていくかもしれない。 | Jā, doyōbi ni ikō ka. Demo, nen no tame ni kasa o motte iku kamoshirenai. | Then let's go Saturday. But just in case, I might bring an umbrella. |
| 7 | M: それがいいね。公園はきっと混んでいるだろうね。 | Sore ga ii ne. Kōen wa kitto konde iru darō ne. | That's good. The park will probably be crowded. |
| 8 | T: 早めに行けば大丈夫なはずだよ。 | Hayame ni ikeba daijōbu na hazu da yo. | It should be fine if we go early. |
| 9 | M: そうだね。楽しみにしてる！ | Sō da ne. Tanoshimi ni shiteru! | True. I'm looking forward to it! |
| 10 | T: 私も！美味しいお弁当も持っていこう。 | Watashi mo! Oishii obentō mo motte ikō. | Me too! Let's bring some delicious bento too. |
Grammar Drills
Fill in the blank with the most appropriate pattern. More than one may be possible; use the hint in parentheses. Answers below.
- 空が暗い。雨が降り___。（visual observation）
- 田中さんは来週結婚する___よ。（I heard from a friend）
- 彼は今日来る___。（logical expectation — we made plans）
- この問題は簡単な___がない。（strong denial）
- 明日の天気は晴れる___。（moderately confident guess）
- あの映画、面白___だよ！（visual/appearance — you see a trailer）
- どうやら彼女は怒っている___。（speaker's own evidence）
- もしかしたら電車が遅れる___ない。（low possibility)
- 先生が言ったから、明日は休み___。（I heard / reported info）
- 彼がそんなことをする___がない。彼は正直な人だ。（strong denial）
Answer Key:
- 降りそうだ（appearance）
- するらしい（hearsay）
- 来るはずだ（logical expectation）
- 簡単なはず（はずがない）
- 晴れるでしょう（confident guess）
- 面白そう（appearance stem + そう）
- 怒っているようだ（speaker's inference）
- 遅れるかもし（かもしれない）
- 休みだそうだ（hearsay そうだ）
- するはず（はずがない）
Translation Practice
English → Japanese
- It might snow tomorrow. (use かもしれない)
- This soup looks delicious! (appearance-そうだ)
- Apparently, Tanaka is leaving the company. (use らしい)
- There is no way this story is true. (use はずがない)
- According to the news, there will be an earthquake. (use 〜によると〜そうだ)
Answers:
- 明日は雪が降るかもしれない。
- このスープ、美味しそう！
- 田中さんは会社を辞めるらしい。
- この話が本当のはずがない。
- ニュースによると、地震があるそうです。
Japanese → English
- 彼はもう帰ったでしょう。
- 外が静かなようですね。
- 田中さんは病気らしいですよ。
- この映画はつまらなそうだ。
- 彼女は試験に合格するはずだ。
Answers:
- He has probably already gone home.
- It seems to be quiet outside.
- It seems Tanaka is sick (I heard).
- This movie looks boring.
- She should pass the exam (I expect her to).
Cultural Note
The careful modulation of certainty in Japanese reflects a broader cultural value of avoiding overconfidence and confrontation. In Japanese social contexts, stating something with too much certainty when you are not sure (or when the topic concerns someone else) can seem rude or presumptuous. The inference patterns in this lesson allow speakers to signal exactly how much they know and where their information comes from — showing intellectual honesty and social awareness simultaneously.
The two uses of 〜そうだ (appearance vs. hearsay) also reflect an important distinction in Japanese epistemology: what you directly observe (目で見た, mite mita) vs. what you were told (聞いた, kiita). Japanese grammar encodes this distinction directly, requiring speakers to be explicit about the source of their knowledge. This is a notably different epistemological stance from many English uses of "it seems" or "apparently," which do not always distinguish between personal observation and hearsay.
Self-Check
- What is the certainty difference between かもしれない and はずだ?
- Explain the two uses of そうだ and how to tell them apart in writing.
- When would you use らしい instead of ようだ? Give an example situation for each.
- Convert to the appropriate form: (a) 雨が降る + "looks like it will" (visual); (b) 雨が降る + "I heard it will" (hearsay).
- Why does はずがない express stronger certainty than かもしれない? What kind of reasoning underpins each?