How can a remark not refer to the speaker's attitude?

Question

_{Source: p 34, Understanding Semantics (2 ed, 2013) by Sebastian Löbner}

  Interjections and exclamations can be used as complete utterances. Other expressives such as hopefully, (un)fortunately or thank God can be inserted into a sentence in order to add a personal attitude to the situation expressed. These additions do not contribute to the proposition, as the following examples illustrate:

(11) a. Fortunately, Bob will arrive tonight. — Really?
  b. I'm glad Bob will arrive tonight. — Really?

The questioning reply 'Really?' is always directed at a proposition asserted before. [1.] In (11a), the remark can only be related to the proposition that Bob will arrive that night ('Will Bob really arrive tonight'), not to the speaker's attitude expressed by fortunately.

How is 1 true? I ask not about what is prescriptively idiomatic. For example, what if in uttering 'Really?', a speaker means >Really? How is this fortunate?< but without uttering the second question?

Answer 1

I agree with Lobner's observation about (11a). The "Really?" does not express doubt about whether Bob's prospective arrival is fortunate, but rather expresses doubt about whether it will actually take place. In the part you've quoted, Lobner does not say anything explicitly about (11b), so let's forget (11b).

I'm not clear about what exactly you are asking. Are you asking us our opinions about whether Lobner's observation about (11a) is true? Well, then I have answered your question. It is simply a question of fact. Others may disagree, and I wouldn't be surprised it they do. If you disagree, well, since you're an English speaker, you're entitled to your opinion.

Answer 2

You are correct: that is possible. But it is far less likely. What the text should have said is: "Really?" is normally and by default directed at a proposition (=excluding commonly used adjuncts) that was asserted before. Consider this example, when there isn't any specific context:

A: Fortunately, Bob will arrive tonight.

B: Really?

A: ...

Now how would A respond?: "yes, he specifically told me so", or "yes, I think it's fortunate that he will arrive tonight". The former seems far more likely. That is what A would say, except if she already suspected that B thought it might not be fortunate that Bob should arrive tonight. So by default Really? refers to a proposition rather than a mere adjunct.

Of course the separation between proposition and adjunct is not strict, and I think that is why the interprettaion you suggest is possible. I suspect the author said "always" because he disregarded this fact.