ことだしOne consideration supporting a decision
This construction presents a relevant circumstance as support for a decision, suggestion, invitation, or judgment. It usually implies that this is one consideration among others, not necessarily the only reason.
How it works
The clause before ことだし supplies a circumstance that helps justify what comes next. The following clause therefore naturally expresses what someone will do, what people should do, or what conclusion seems reasonable.
Supporting a proposal or decision
The stated circumstance gives the listener a reason to accept the proposed action, while leaving room for other considerations.
風も弱くなったことだし、そろそろ出発しませんか。
The wind has died down too, so why don't we get going soon?
AnalyzeThis is a tactful invitation. The weaker wind is presented as one good reason to leave now.
必要な資料もそろったことだし、企画書を書き始めよう。
Now that the necessary materials are ready too, I'll start writing the proposal.
AnalyzeThe speaker uses the circumstance to support a decision about what to do next.
会場も静かなことだし、ここで打ち合わせをしましょう。
The venue is quiet too, so let's hold the meeting here.
AnalyzeThis shows the required な after a na-adjective.
One reason, with others in the background
ことだし often has the feel of “given this circumstance as well.” The other considerations do not have to be stated. Words meaning “also” or “too” frequently make this nuance especially clear, but they are not required.
Adding the reason afterward
今日はここまでにしよう。もう遅いことだし。
Let's stop here for today. It's already late, after all.
AnalyzeIn conversation, the decision can come first and the supporting circumstance can be added afterward.
Choosing among reason expressions
し lists reasons or properties more directly and can be repeated several times. ことだし packages one circumstance more reflectively as grounds for a decision or proposal. By contrast, ので can simply state a straightforward reason, including the main or only reason, without suggesting a larger set of considerations.
More examples
雨も上がったことだし、少し散歩してこよう。
The rain has stopped too, so I think I'll go for a short walk.
Analyzeせっかく皆が集まったことだし、記念写真を撮りましょう。
Since everyone has made it here, let's take a commemorative photo.
Analyze急ぐ必要もないことだし、途中で昼食を取っていこう。
There's no need to hurry either, so let's stop for lunch on the way.
Analyze体調もよくなってきたことだし、来週から練習に戻るつもりだ。
My condition has been improving too, so I plan to return to practice next week.
Analyzeこの店は評判もいいことだし、予約しておこう。
This restaurant has a good reputation too, so I'll make a reservation.
Analyze今日は客も少なくて静かなことだし、奥の席で話しませんか。
There aren't many customers and it's quiet today, so why don't we talk at a table in the back?
Analyze