What's the nuance of ...ましょう to express intent?

Question

十万円あげましょう。 I'll give you 100,000 yen.

手伝いましょう。 I'll help you.

I've seen sentences of intent like this, but I don't understand the nuance of the speaker using ...ましょう instead of structures like 「手伝います。」「手伝ってあげます。」「手伝おうと思います。」

For example, in Genki II pg.75, one of the sentences above is part of this exchange:

A: 十万円あげましょう。何に使いますか。 I'll give you 100,000 yen. What will you use it for?

B: 旅行に行こうと思います。I'll go on a trip.

Why does B express intent with volitional+と思います, but A expresses intent with only ...ましょう?

Answer 1

Since 行きましょう is the polite version of 行こう, your question boils down to how to use the volitional form properly in general. It's used in several ways:

• Similarly to English "Let's ～", it can be used to invite or encourage someone to take an action.
• When used for one's own action, it can express the feeling of "I decided to do ～" or "Let me ～".
• When there's no listener, it is used to prompt one's own action. It's like "Okay let's ～", "I made up my mind and ～", "Oh I should ～" or "Now I'll ～" said to yourself.

手伝いましょう and 手伝います are both natural expressions, but the former sounds like the person just decided to do it, while the latter can also be used to state a known plan. In English, the former might be closer to "Let me help you" and the latter to "I will help you".

A said 10万円あげましょう, which can be taken as an invitation ("Let's give them 100,000 yen") if the conversation is about what to give to a third person. But since there's no previous context, A's statement only means "Let me give you 10,000 yen". It's also okay to say 10万円あげます here (it sounds like a known plan/fact, but the difference is small).

On the other hand, B's response can be either 旅行に行きます or 旅行に行こうと思います, but he should not say 旅行に行きましょう (or 行こう) as a response here. In my intuition, if he said it at this point, it would sound like an invitation to A ("Let's go on a trip together"), which is inappropriate. It's difficult for me to explain why, but perhaps this is because it's not yet a situation for concretely self-prompting or deciding on a specific action or plan. Since B has just been offered 100,000 yen, there's no time to hesitate or make a decision. If B is already sure about how to use it, he would say 旅行に行きます, and if he is telling a likely use hypothetically, 旅行に行くと思います would be appropriate. After pondering or discussing for 30 seconds about how to use 100,000 yen, saying 旅行に行きましょう/行こう would sound natural.

Answer 2

As you must have learned, 〜ましょうか can be understood either as (a) an offer by the speaker to do something for the listener (Shall I … for you?) or (b) a suggestion that the speaker and the listener do something together (Shall we … together?). In either case, the speaker involves the listener in one way or another.

The non-question form 〜ましょう also has this sense of involvement. When the speaker and the listener do the action of the verb together, it is translated as “Let’s … (together)” When the speaker is the sole actor as in your example, it still sounds like an offer to the listener, albeit a unilateral one for which the speaker doesn't expect an answer from the listener.

十万円あげようと思います would be understood as a declaration of intent. It would be less clear who the speaker plans to give the money.

旅行に行きましょう in that dialogue would be understood as a suggestion that they go on a trip together.

Answer 3

Normally,

旅行に行こうと思います

would be more equivalent to

I'm thinking of going on a trip.

A however offers 100,000 yen and then asks what B would do with it. I think Genki is omitting a bit too much. I would have translated B's response as

I'd consider going on a trip.

If the money had already changed hands, then perhaps

I'm considering going on a trip.

The nuance of the volitional can at times be hard to capture. The dialogue to me sounds more like,

How about I give you 100,000 yen. What are you going to use it for?

I think I'll go on a trip.