～でしょう

How it works

でしょう is the conjectural form of です: instead of asserting that something is so, it says it is probably so. It attaches to plain forms: 降るでしょう, 降らないでしょう, 降ったでしょう, 高いでしょう. After nouns and な-adjectives it attaches directly, with no だ: 雨でしょう, 静かでしょう. The plain equivalent is だろう (雨だろう), common in writing and in casual male speech.

Intonation decides the job. Falling でしょう is an educated guess about something outside your control: 明日は寒いでしょう. Rising でしょう？ turns to the listener for agreement: 寒いでしょう？ = cold, isn't it? or see, I told you. ～でしょうか asks a question more softly than ～ですか: トイレはどこでしょうか。

Because it hedges, でしょう often pairs with たぶん or きっと, and it is the register of weather presenters and announcers: 明日は全国的に晴れるでしょう。

Examples

• 明日は晴れるでしょう。（あした は はれる でしょう。）— It will probably be sunny tomorrow.
• 午後から雨でしょう。（ごご から あめ でしょう。）— It will probably rain from the afternoon.
• この問題は難しいでしょう。（この もんだい は むずかしい でしょう。）— This problem is probably difficult.
• 田中さんは今日は来ないでしょう。（たなかさん は きょう は こない でしょう。）— Mr. Tanaka probably won't come today.
• あの人は先生でしょう？（あの ひと は せんせい でしょう？）— That person is a teacher, right?
• 週末は暇でしょう？（しゅうまつ は ひま でしょう？）— You're free this weekend, aren't you?

Compare with

• ～と思う names the speaker as the source of the guess and is the conversational default: 雨が降ると思います. でしょう sounds more detached, like a forecast.
• ～かもしれない is a bare possibility, roughly fifty-fifty: 雨が降るかもしれません. でしょう is fairly confident.
• ～はずだ (N3) is an expectation backed by evidence or logic: 八時に着くはずです = it should arrive at eight (the timetable says so), versus 八時に着くでしょう = it will probably arrive at eight.

Traps for Spanish, English and French speakers

• Spanish lloverá and French il pleuvra are plain future tenses, so learners take でしょう for the future marker and say ✗ 明日は学校に行くでしょう about themselves, which sounds as if they have no idea what they will do. Japanese has no future tense: ✓ 明日は学校に行きます, and でしょう is kept for things outside your control.
• After learning that と思う needs だ, learners carry it over: ✗ 雨だでしょう, ✗ 先生ですでしょう. Nouns and な-adjectives attach directly: ✓ 雨でしょう, ✓ 先生でしょう？
• ¿Verdad?, right? and n'est-ce pas? all map to both ね and でしょう？, but they are not interchangeable. いい天気ですね shares the moment; いい天気でしょう？ pushes the listener to concede your point, so use ね unless you are checking or insisting.
• The plain form だろう is blunt and masculine; a Spanish speaker in tú mode who tells a colleague 雨だろう sounds rough. Stay with でしょう in polite talk, and in casual talk prefer と思う or かな.