Presumptive
Production Rules:
| Rule | Meaning | |
| Plain Affirmative | [う-stem] & だろう [u-stem] & darou |
X probably [does], X probably will [do] |
| Polite Affirmative | [う-stem] & でしょう [u-stem] & deshou |
|
| Plain Negative | [あ-stem] + ない & だろう [a-stem] + nai & darou |
X probably doesn't [do], X probably won't [do] |
| Polite Negative | [あ-stem] + ない & でしょう [a-stem] + nai & deshou |
Note that the presumptive is formed by simply adding だろう (darou) for the plain case or でしょう (deshou) for the polite case to the plain forms of the nonpast indicative.
Inflection Examples:
| Plain Affirmative | Polite Affirmative | Plain Negative | Polite Negative | |
| 食べる taberu (to eat) |
食べるだろう taberu darou |
食べるでしょう taberu deshou |
食べないだろう tabenai darou |
食べないでしょう tabenai deshou |
| 話す hanasu (to speak) |
話すだろう hanasu darou |
話すでしょう hanasu deshou |
話さないだろう hanasanai darou |
話さないでしょう hanasanai deshou |
| 歩く aruku (to walk) |
歩くだろう aruku darou |
歩くでしょう aruku deshou |
歩かないだろう arukanai darou |
歩かないでしょう arukanai deshou |
| 泳ぐ oyogu (to swim) |
泳ぐだろう oyogu darou |
泳ぐでしょう oyogu deshou |
泳がないだろう oyoganai darou |
泳がないでしょう oyoganai deshou |
| 呼ぶ yobu (to call) |
呼ぶだろう yobu darou |
呼ぶでしょう yobu deshou |
呼ばないだろう yobanai darou |
呼ばないでしょう yobanai deshou |
| 飲む nomu (to drink) |
飲むだろう nomu darou |
飲むでしょう nomu deshou |
飲まないだろう nomanai darou |
飲まないでしょう nomanai deshou |
| 死ぬ shinu (to die) |
死ぬだろう shinu darou |
死ぬでしょう shinu deshou |
死なないだろう shinanai darou |
死なないでしょう shinanai deshou |
| 作る tsukuru (to make) |
作るだろう tsukuru darou |
作るでしょう tsukuru deshou |
作らないだろう tsukuranai darou |
作らないでしょう tsukuranai deshou |
| 待つ matsu (to wait) |
待つだろう matsu darou |
待つでしょう matsu deshou |
待たないだろう matanai darou |
待たないでしょう matanai deshou |
| 洗う arau (to wash) |
洗うだろう arau darou |
洗うでしょう arau deshou |
洗わないだろう arawanai darou |
洗わないでしょう arawanai deshou |
Irregulars:
| Plain Affirmative | Polite Affirmative | Plain Negative | Polite Negative | |
| する suru (to do) |
するだろう suru darou |
するでしょう suru deshou |
しないだろう shinai darou |
っしないでしょう shinai deshou |
| 来る kuru (to come) |
くるだろう kuru darou |
くるでしょう kuru deshou |
こないだろう konai darou |
こないでしょう konai deshou |
Usage Notes & Examples:
- This form is used to express some doubt or conjecture on the part
of the speaker, similar to interjecting "probably" in English. Without
combining it with another form like the progressive, the meaning is similar
to the nonpast indicative, expressing a conjecture about a state, or
habitual or future action. In Japanese one doesn't speak of someone else's
presumptive actions (desires, etc.) with any certainty, so among other
ways, this form can be used to add the necessary uncertainty.
- 経済状況はすぐによくなるだろう。
keizai joukyou ha sugu ni yoku naru darou.
Economic conditions will probably get better soon. - 田中さんは随分忙しいそうで、今夜
来ないだろう。
tanaka-san wa zuibun isogashii sou de, kon'ya konai darou.
I heard that Mr. Tanaka is extremely busy, so he probably won't come tonight. - ここから東京まで飛行機で13時間ぐらい
かかるでしょう。
koko kara toukyou made hikouki de juusan jikan gurai kakaru deshou.
From here to Tokyo by plane probably takes about 13 hours.
- 経済状況はすぐによくなるだろう。
- This form can also be used to solicit agreement or soften the tone of a statement.
- The plain forms using だろう (darou) can sound somewhat abrupt or assertive, even when talking to equals. You may want to use the polite forms even in friendly contexts. It is acceptable to use the plain forms when talking to yourself, or to people you would otherwise be on informal terms with about impersonal third-party subjects. Of course, this is all a matter of degree. An all-male group of friends, or a superior speaking to an inferior would not be likely to use the polite forms.