まいProbably will not
まい expresses the speaker's judgment that an event probably will not happen or that a state is unlikely to be true. In modern Japanese, it has a formal, literary, or old-fashioned tone.
Making a negative prediction
まい does not simply make a verb negative. It presents a considered prediction: based on the circumstances, the speaker judges that something probably will not happen. Nonhuman subjects and events outside anyone's control often make this reading especially clear.
Clear negative conjectures
この雨は夜までにはやむまい。
This rain probably will not stop by tonight.
Analyzeこの計画が予定どおり進むことはあるまい。
It is unlikely that this plan will proceed as scheduled.
Analyzeあるまい here means that the stated possibility is judged unlikely.
こんな小さな物音では、赤ん坊は起きまい。
A noise this slight probably will not wake the baby.
Analyze起きまい uses the ichidan stem: the final る of 起きる is removed before まい.
Prediction or personal resolve?
The same form can also express a person's resolve not to act. Ask what the sentence is doing: if the speaker is judging how likely an event is, it is negative conjecture; if an agent is deciding not to perform a controllable action, it is negative volition. Subject, control, and context—not the form alone—make the distinction.
More examples
この古い鍵では、扉は開くまい。
This old key probably will not open the door.
Analyze一度失われた信頼は、容易には戻るまい。
Once lost, trust is unlikely to return easily.
Analyzeこの霧では、山頂は見えまい。
The summit probably will not be visible in this fog.
Analyze数日の遅れが最終結果を左右することはあるまい。
A delay of a few days is unlikely to affect the final result.
Analyzeあれほど事情を知る彼女が、そのうわさを信じることはあるまい。
Given how well she knows the circumstances, she is unlikely to believe that rumor.
Analyzeこの程度の変更が、利用者に大きな混乱を招くことはあるまい。
A change of this scale is unlikely to cause major confusion for users.
Analyze