I think there are actually two separate phenomena under discussion here, which look superficially similar, but actually don’t have much to do with each other.
First phenomenon
Alice: Would you help me fix my car muffler?
Bob: Sure.
Alice: That way you won’t have to listen to my car roaring like a jet engine every time I leave my house (since we’re neighbors and all).
Second Phenomenon
Alice: Would you help me fix my car muffler?
Bob: Sure.
Alice: The noise sure does give me a headache, I want it fixed as soon as possible.
Bob: Ah, okay. I’m alright with cars, but not stellar, so how about I just pay for you to get it fixed at a garage instead? You can owe me one.
The first phenomenon seems bad for the reasons you describe in the great-grandparent comment. It also just seems strange from a linguistic perspective to keep trying to persuade someone to do something after they’ve already agreed to do it. Though if the order were reversed so that Alice gave her reason before Bob assented, it would still seem bad for the reasons you mention (because Alice’s reason isn’t all that good) but not linguistically odd.
The second phenomenon, on the other hand, seems like a good thing to me, and as far as I can tell it isn’t affected by the problems you mention. In particular, Alice giving extra reasons doesn’t absolve her of any debt she owes to Bob for the favor; in fact, in this particular scenario I would perceive her to owe a greater debt to Bob if he pays for her to have her car fixed than if he helps her fix it (though I have no idea how universal this intuition would be, and am agnostic about whether it’s correct morally). It actually seems like Bob and Alice both benefit from Alice giving her reason (at least the way I’m imagining the extra details of the scenario): Alice gets her car fixed faster, and Bob gets to avoid spending a large amount of time fixing the car. As I’m imagining the scenario, Bob would have done it if he thought Alice was asking him e.g. partially as an excuse to spend more time with him, because he also would have wanted to do that, but once it was revealed that Alice’s primary objective was to get the car fixed as fast as possible, Bob was able to save himself some time and (as I mentioned above) get Alice in debt to him even more than she otherwise would have been. So they both benefited.
The distinction seems to be that in the first phenomenon, Alice mentions a reason why it would benefit Bob to help her fix her car, whereas in the second phenomenon, Alice mentions the underlying reason she wants the car fixed. I can see how Alice mentioning a reason Bob would want to help fix the car could shift the situation to an instance of your third case, but I don’t see how Alice mentioning the underlying reason she wants the car fixed could do so, since that doesn’t make it any more in Bob’s interest to help her (except insofar as fulfilling Alice’s preferences is part of Bob’s interest, but that’s an instance of your second case).
It seems the fact that these two phenomena are distinct has only been obliquely acknowledged elsewhere in this thread, so I wanted to make it more explicit. In particular, if I’m interpreting everyone correctly then most of what people have said in this thread has been in support of the second phenomenon, and most of your objections have been objections to the first phenomenon, so to a certain extent people seem to be talking past each other.
Also, you said in the parent comment that you object to what looks to me like the second phenomenon, but you didn’t give your reasons there. Nothing wrong with that, but if you’re willing I’d be interested in hearing those reasons, because I’m having trouble imagining what someone could object to about the second phenomenon. The only thing I can think of is this: If you know the “big-picture goal” behind someone’s request, perhaps that obligates you to put in more effort to help them towards that big-picture goal than if you only knew the contents of the immediate request, i.e. you have to put in time to think about whether there’s a better way to accomplish the big-picture goal, and if that way ends up being more effortful than the original ask you still have to help with it, etc. That might be concerning in a similar way to your objection to the first phenomenon, if it’s true.
I think there are actually two separate phenomena under discussion here, which look superficially similar, but actually don’t have much to do with each other.
First phenomenon
Alice: Would you help me fix my car muffler?
Bob: Sure.
Alice: That way you won’t have to listen to my car roaring like a jet engine every time I leave my house (since we’re neighbors and all).
Second Phenomenon
Alice: Would you help me fix my car muffler?
Bob: Sure.
Alice: The noise sure does give me a headache, I want it fixed as soon as possible.
Bob: Ah, okay. I’m alright with cars, but not stellar, so how about I just pay for you to get it fixed at a garage instead? You can owe me one.
The first phenomenon seems bad for the reasons you describe in the great-grandparent comment. It also just seems strange from a linguistic perspective to keep trying to persuade someone to do something after they’ve already agreed to do it. Though if the order were reversed so that Alice gave her reason before Bob assented, it would still seem bad for the reasons you mention (because Alice’s reason isn’t all that good) but not linguistically odd.
The second phenomenon, on the other hand, seems like a good thing to me, and as far as I can tell it isn’t affected by the problems you mention. In particular, Alice giving extra reasons doesn’t absolve her of any debt she owes to Bob for the favor; in fact, in this particular scenario I would perceive her to owe a greater debt to Bob if he pays for her to have her car fixed than if he helps her fix it (though I have no idea how universal this intuition would be, and am agnostic about whether it’s correct morally). It actually seems like Bob and Alice both benefit from Alice giving her reason (at least the way I’m imagining the extra details of the scenario): Alice gets her car fixed faster, and Bob gets to avoid spending a large amount of time fixing the car. As I’m imagining the scenario, Bob would have done it if he thought Alice was asking him e.g. partially as an excuse to spend more time with him, because he also would have wanted to do that, but once it was revealed that Alice’s primary objective was to get the car fixed as fast as possible, Bob was able to save himself some time and (as I mentioned above) get Alice in debt to him even more than she otherwise would have been. So they both benefited.
The distinction seems to be that in the first phenomenon, Alice mentions a reason why it would benefit Bob to help her fix her car, whereas in the second phenomenon, Alice mentions the underlying reason she wants the car fixed. I can see how Alice mentioning a reason Bob would want to help fix the car could shift the situation to an instance of your third case, but I don’t see how Alice mentioning the underlying reason she wants the car fixed could do so, since that doesn’t make it any more in Bob’s interest to help her (except insofar as fulfilling Alice’s preferences is part of Bob’s interest, but that’s an instance of your second case).
It seems the fact that these two phenomena are distinct has only been obliquely acknowledged elsewhere in this thread, so I wanted to make it more explicit. In particular, if I’m interpreting everyone correctly then most of what people have said in this thread has been in support of the second phenomenon, and most of your objections have been objections to the first phenomenon, so to a certain extent people seem to be talking past each other.
Also, you said in the parent comment that you object to what looks to me like the second phenomenon, but you didn’t give your reasons there. Nothing wrong with that, but if you’re willing I’d be interested in hearing those reasons, because I’m having trouble imagining what someone could object to about the second phenomenon. The only thing I can think of is this: If you know the “big-picture goal” behind someone’s request, perhaps that obligates you to put in more effort to help them towards that big-picture goal than if you only knew the contents of the immediate request, i.e. you have to put in time to think about whether there’s a better way to accomplish the big-picture goal, and if that way ends up being more effortful than the original ask you still have to help with it, etc. That might be concerning in a similar way to your objection to the first phenomenon, if it’s true.