だろう
darou
だろう isn't a guess — it's a ball rolled toward the other person
The picture Instead of nailing your sentence down, you roll a ball gently toward the person across from you. だろう rolls the judgment over to the listener; だ and です nail it down where it stands.
Where the picture shows up in だろう
-
rolled into the fog
明日はたぶん晴れるでしょう。
ashita wa tabun hareru deshō
It'll probably be clear tomorrow.
The forecaster rolls a ball marked 'clear' toward the front of the screen and lets go.
This is why forecasts always end in でしょう — they never nail it down.
-
rolled to yourself
彼はもう知っているだろう。
kare wa mō shitte iru darō
He must already know.
Alone in an empty room, you roll the ball at the wall just to see.
だろう is plain; でしょう is its polite form.
-
rolled over for agreement
長旅で疲れたでしょう?
nagatabi de tsukareta deshō
You must be tired after that long trip.
You roll the ball to the feet of someone who has travelled far, and wait for a nod.
With a rising tone it becomes a warm read of how the other person feels.
-
set gently in their hands
この書き方でよろしいでしょうか。
kono kakikata de yoroshii deshō ka
Would writing it this way be all right?
You hold the document in both hands and set it on their palm as gently as a ball.
でしょうか steps back one pace from ですか and sounds more deferential.
-
pointing back at a ball you rolled
だから言っただろう。
dakara itta darō
See, I told you.
You point a finger at the ball you rolled out earlier: there it is, right where you left it.
Pushed as だろう? it turns confrontational — never aim it upward at a senior.
All of it in one picture
だろう is not a degree of certainty but a question of where you roll the ball. Roll it into the fog and you get the forecaster's でしょう; roll it at the wall alone and you get talking to yourself. Roll it to someone's feet and wait, and it asks for agreement; set it on their palm with both hands and it becomes the deferential でしょうか. Point back at the ball you rolled earlier and it becomes 言っただろう. It is always the same ball — only the place where it comes to rest changes.