Expressing Uncertainty in Japanese

Uncertain Businesswoman
John Wildgoose

There are several ways to express uncertainty in Japanese. "~ darou" is a plain form of "~ deshou," and means "will probably." The adverb "tabun (perhaps)" is sometimes added.

Kare wa ashita kuru deshou.
He will probably come tomorrow.
Ashita wa hareru darou.
It will be sunny tomorrow.
Kyou haha wa tabun
uchi ni iru deshou.

My mother will probably
be home today.

"~ darou" or "~deshou" is also used to form a tag question. In this case, you usually can tell the meaning from the context.

Tsukareta deshou.
You were tired, weren't you?
Kyou wa kyuuryoubi darou.
Today is a payday, isn't it?

"~ darou ka" or "~ deshou ka" is used when guessing with doubt. "~ kashira" is used only by females. A similar expression used by both genders is "~ kana," though it is informal. These expressions are close to "I wonder ~" in English.

Emi wa mou igirisu ni
itta no darou ka.

I wonder if Emi has
already gone to England.
Kore ikura kashira.
I wonder how much this is.
Nobu wa itsu kuru no kana.
I wonder when Nobu will come.

"~ kamoshirenai" is used to express a sense of probability or doubt. It shows, even more, uncertainty than "~ darou" or "~ deshou". It is used when you don't know all the facts and are often just guessing. It is similar to the English expression "might be." The formal version of "~ kamoshirenai" is "kamoshiremasen".

Ashita wa ame kamoshirenai.
It might rain tomorrow.
Kinyoubi desu kara,
kondeiru kamoshiremasen.

Since it is Friday, it might be busy.

* Compare these sentences.

Kare wa tabun kin-medaru o
toru deshou.

He will probably get the gold medal.
Kare wa kin-medal o
totta no kana.

I wonder if he got the gold medal.
Kare wa kin-medaru o
toru kamoshirenai.

He might get the gold medal.

The last thing to mention is, "~ darou" or "~ deshou" can't be used when referring to one's own actions, though "~ kamoshirenai" can be used in these situations.

Ashita watashi wa Kobe ni
iku kamoshirenai.

I might go to Kobe tomorrow.
Ashita watashi wa Kobe ni
iku darou.
Ashita ane wa Kobe ni iku darou.
My sister will go to Kobe tomorrow.