Page 235 - Basic Japanese

(compare Tanaka-san datta no deshō ‘it must have been Mr.

Tanaka’).
There already existed a polite tentative for verbs:

ikimashō, hanashimashō, asobimashō. These polite tentatives

once had the meaning ‘will probably do’ just as the polite
copula deshō still has the meaning ‘will probably be.’
Sometimes the tentatives of verbs are still used with the

‘probably’ meaning. For example, in modern writings you

will see arō (= aru darō), narō (= naru darō), dekiyō (= dekiru
darō), ieyō (= ieru darō ‘probably can say’) and also tentative

adjectives in -karō (= -i darō) such as yokarō (= ii darō) and
nakarō (= nai darō).

For the meaning ‘probably,’ a plain form of the verb is
used, either imperfect or perfect, depending on the

meaning, followed by the tentative copula deshō (from no

deshō ‘it’s probably a fact that’ with the no dropped). This is
quite standard usage and often has the flavor of English

‘must (be), I bet that…, I’ll bet…,’ Sometimes kitto or tabun
‘no doubt, probably’ is added, often at the very beginning of

the sentence, just to emphasize the probability. For
example:

「これから株価が上がるでしょう。」
“Kore kara kabuka ga agaru deshō.”
“I guess the stock will go up from now on.”

「たぶんそうでしょう。」
“Tabun sō deshō.”
“It will probably do so.”

5.8. …かね …ka ne