Express possibility: 〜かもしれない (Might / Maybe)

Mental Model: The 50/50 Coin Toss

When you want to state that something is possible without committing to whether it is true, Japanese turns to 〜かもしれない.

Think of it as a 50/50 coin toss in mid-air:

• You are not declaring that the event will happen.
• You are not declaring that it won't happen.
• You are simply acknowledging: “There is a genuine, non-zero possibility.”

Contrast: 〜でしょう vs 〜かもしれない

Learners often confuse 〜でしょう (or 〜だろう) with 〜かもしれない:

• Likelihood around 75–80% (〜でしょう): Expresses a strong subjective expectation: “It will probably happen / I presume so.” 明日は 雨が 降るでしょう。(あしたは あめが ふるでしょう。) (“It will probably rain tomorrow.”)
• Likelihood around 50% (〜かもしれない): Expresses genuine epistemic uncertainty: “It might happen (or it might not; who knows?).” 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。) (“It might rain tomorrow.”)

The Fascinating Etymology

Where does this phrase come from? Breaking it down reveals its logic: • か = Interrogative particle (“whether”). • も = Inclusive particle (“even”). • 知れない(しれない) = Potential negative form of 知る(しる) (“cannot be known”).

Put together, かも知れない literally means: “Even whether [X is the case] cannot be known.”

Plain-Form Attachment Rules

かもしれない attaches directly to the plain form (informal form) of verbs and adjectives, but has one critical rule for nouns and な-adjectives:

• Verbs (Plain Present / Past / Negative): 行く → 行くかもしれない (Might go) 行かない → 行かないかもしれない (Might not go) 行った → 行ったかもしれない (Might have gone)
• い-Adjectives (Direct Attachment): 忙しい → 忙しいかもしれない(いそがしいかもしれない) (Might be busy) 寒かった → 寒かったかもしれない(さむかったかもしれない) (Might have been cold)
• な-Adjectives (Drop だ!): 暇 → 暇かもしれない(ひまかもしれない) (Never say: *暇だかもしれない) 暇じゃないかもしれない (Might not be free)
• Nouns (Drop だ!): 雨 → 雨かもしれない(あめかもしれない) (Never say: *雨だかもしれない) 日本人 → 日本人かもしれない(にほんじんかもしれない) (Might be Japanese)

The Three Register Tiers

You will hear this structure across three distinct social levels:

• Tier 1: Polite Spoken (〜かもしれません): Standard for coworkers, acquaintances, teachers, and service staff. 田中さんは 今日、来ないかもしれません。(たなかさんは きょう、こないかもしれません。) (“Tanaka-san might not come today.”)
• Tier 2: Plain / Written (〜かもしれない): Used in casual conversation with close friends, personal journals, and news commentary. 鍵を 忘れたかもしれない。(かぎを わすれたかもしれない。) (“I might have forgotten my keys.”)
• Tier 3: Casual Shorthand (Bare 〜かも): In modern daily life, messaging apps, and casual speech across Japan, speakers constantly shorten the entire phrase to just かも: 無理かも。(むりかも。) (“That might be impossible / Probably can't make it.”) そうかも。 (“That might be so / Maybe!”) 遅れるかも。(おくれるかも。) (“I might be running late.”)

The Cultural Shield: Japanese Diplomatic Softening

Beyond literal probability, 〜かもしれません is a fundamental cultural cushion. Japanese communication prioritizes avoiding friction and bluntness. Even when a native speaker is 95% certain that someone made an error or that a meeting is cancelled, they will intentionally say:

間違っているかもしれません。(まちがっているかもしれません。) (“This might be mistaken...”)

Framing facts as possibilities gives everyone room to save face without confronting someone directly.