から and んですが to make a request

Question

I've been using Genki as the main reference and it said から could be used to explain the reason the speaker is asking the listener to do something:

1. 時間がありませんから、急いでください。
2. 掲示板に貼ってありますから、もう一度見てみてください。
3. 暑いから窓を開けてください。

But lately I came across んですが in Minna no Nihongo and some web sites and they recommend using this to make a request:

1. 車を買いたいんですが、お金を貸してください。
2. 鉛筆を忘れたんですが、貸してもらえませんか。
3. 明日の会議の資料が必要なんですが、メールで送っていただけませんか。

So, when it comes to making requests, how do から and んですが differ?

Answer 1

から is equivalent (about as much as you ever get between the two languages) to the English "from". It covers both the literal sense (a starting point for motion) and the metaphorical sense that's a rough synonym for "since" (i.e., the premises that lead to a conclusion).

Asking a question this way, while still polite, implies that making the request follows naturally from the circumstances.

んですが is (contracted) explanatory-の + ordinary polite copula です + sentence-connective が. Grammatically, the combination is roughly equivalent to ので (see also), but I would say the usage is fairly different. By phrasing things this way, you emphasize that the circumstances stand independently of the request.

In effect, this is more humble. English translations of sentences using sentence-connective が often turn into a single sentence using "although" or "but". That doesn't work here (since the circumstances aren't counter to the request), but it helps understand the nuance.

Let's take one example each.

時間がありませんから、急いでください。

"Since I don't have time, please hurry." There's a natural logic to it, and a presumption that the request is reasonable.

The other examples, similarly, request accommodation.

車を買いたいんですが、お金を貸してください。

"I'd like to buy a car, so please lend me (the) money (for it)." This is a considerable imposition, and apparently motivated by a want rather than a need.

The other examples, similarly, request a favour, perhaps to cover the speaker's prior error.