Lesson17:かもしれません-Understanding Japanese Conjecture: Expressing What “Might Be” or “Must Be”

When you’re speaking Japanese, you often need to express uncertainty, probability, or strong conviction. Unlike English, which might just use “maybe” or “probably,” Japanese has several distinct grammatical patterns that convey different levels of certainty. Mastering these will significantly improve your naturalness and precision!

Let’s break down the nuances of “かもれない,” “だろう/でしょう,” “はずだ,” and “に違いない.”

かもしれません (kamoshiremasen): “Might Be,” “May Be,” “Possibly”

This is your go-to phrase when you’re not very certain about something. It suggests that something might be true, but there’s also a good chance it’s not. It’s often used when you’re speculating or making a gentle suggestion.

How to connect it: Just attach it to the plain form of verbs, i-adjectives, na-adjectives (without だ), and nouns (without だ).

• Verbs (plain form) + かもしれません
  • 行く (iku – go) → 行くかもしれません (iku kamoshiremasen – I might go)
  • 食べた (tabeta – ate) → 食べたかもしれません (tabeta kamoshiremasen – He might have eaten)
• I-adjectives (plain form) + かもしれません
  • 高い (takai – expensive) → 高いかもしれません (takai kamoshiremasen – It might be expensive)
• Na-adjectives (stem) + かもしれません
  • 静か (shizuka – quiet) → 静かかもしれません (shizuka kamoshiremasen – It might be quiet)
• Nouns + かもしれません
  • 学生 (gakusei – student) → 学生かもしれません (gakusei kamoshiremasen – He might be a student)
  • 雨 (ame – rain) → 雨かもしれません (ame kamoshiremasen – It might rain)

When to use it:

• Low certainty/possibility: You think something could happen, but you’re not confident.
  • 明日は雨が降るかもしれません。
    • (Ashita wa ame ga furu kamoshiremasen.)
    • It might rain tomorrow. (It might not, too.)
• Softer/indirect expressions: You want to avoid being too direct or blunt. It’s polite!
  • このケーキは少し甘すぎるかもしれませんね。
    • (Kono keeki wa sukoshi amasugiru kamoshiremasen ne.)
    • This cake might be a little too sweet. (Instead of saying “It’s too sweet.”)

だろう / でしょう (darou / deshou): “Probably,” “Likely,” “I suppose”

These express a moderate to high level of certainty. You’re making a guess based on some evidence or general knowledge, and you feel it’s more likely than not. 「でしょう」 is the more polite form of 「だろう」.

How to connect it: Similar to 「かもしれません」, you attach it to the plain form.

• Verbs (plain form) + だろう/でしょう
  • 行く (iku) → 行くだろう/でしょう (It will probably go)
• I-adjectives (plain form) + だろう/でしょう
  • 高い (takai) → 高いだろう/でしょう (It’s probably expensive)
• Na-adjectives (stem) + だろう/でしょう
  • 静か (shizuka) → 静かだろう/でしょう (It’s probably quiet)
• Nouns + だろう/でしょう
  • 学生 (gakusei) → 学生だろう/でしょう (He’s probably a student)

When to use it:

• Higher probability: You expect something to happen or be true.
  • 明日は晴れるでしょう。
    • (Ashita wa hareru deshou.)
    • It will probably be sunny tomorrow. (You have a good reason to believe so, like a weather forecast.)
• Making a prediction:
  • 彼は来るだろう。
    • (Kare wa kuru darou.)
    • He’ll probably come.

はずだ (hazu da): “Should be,” “Is supposed to be”

This phrase indicates a high level of certainty based on a reason, expectation, or established plan. You’re quite confident because there’s a logical basis for your belief. It’s stronger than だろう/でしょう.

How to connect it:

• Verbs (plain form) + はずだ
  • 行く (iku) → 行くはずだ (I am supposed to go / He should go)
• I-adjectives (plain form) + はずだ
  • 高い (takai) → 高いはずだ (It should be expensive)
• Na-adjectives (stem) + な + はずだ
  • 静か (shizuka) → 静かなはずだ (It should be quiet)
• Nouns + の + はずだ
  • 学生 (gakusei) → 学生のはずだ (He should be a student)

When to use it:

• Based on expectation/reason: You have a reason to believe something is true.
  • 彼は昨日出発したから、もう着いているはずだ。
    • (Kare wa kinou shuppatsu shita kara, mou tsuite iru hazu da.)
    • He left yesterday, so he should have arrived already. (Logical deduction)
• Confirming a plan:
  • 会議は3時に始まるはずだ。
    • (Kaigi wa san-ji ni hajimaru hazu da.)
    • The meeting is supposed to start at 3 o’clock. (According to the schedule)

に違いない (ni chigainai): “Must be,” “Undoubtedly,” “No doubt”

This is the strongest expression of conjecture, indicating almost 100% certainty. You have strong evidence or a very firm conviction that something is true. There’s virtually no room for doubt in the speaker’s mind.

How to connect it: Attach it to the plain form of verbs, i-adjectives, na-adjectives (without だ), and nouns (without だ).

• Verbs (plain form) + に違いない
  • 行く (iku) → 行くに違いない (He must go)
• I-adjectives (plain form) + に違いない
  • 高い (takai) → 高いに違いない (It must be expensive)
• Na-adjectives (stem) + に違いない
  • 静か (shizuka) → 静かに違いない (It must be quiet)
• Nouns + に違いない
  • 学生 (gakusei) → 学生に違いない (He must be a student)

When to use it:

• Strong conviction/evidence: You are extremely sure based on solid evidence.
  • 彼の話し方からすると、犯人は彼に違いない。
    • (Kare no hanashikata kara suru to, hannin wa kare ni chigainai.)
    • Judging from the way he talks, the culprit must be him.
• When you can’t imagine any other possibility:
  • こんなにおいしいのだから、有名なレストランの料理に違いない。
    • (Konna ni oishii no dakara, yuumei na resutoran no ryouri ni chigainai.)
    • Since it’s this delicious, it must be food from a famous restaurant.

Quick Certainty Scale: From Most Certain to Least Certain

Here’s a simple way to remember the approximate level of certainty for each expression:

By understanding these different levels of certainty, you can choose the perfect expression to match your thoughts and the situation in Japanese. Keep practicing, and you’ll naturally pick up the nuances!