Suppose I’m hanging out with a friend and I point to an object on the table in front of me and utter a subsentential expression questioningly: “—–?” Sometimes I can be construed as having asked something about the object pointed to, e.g. if I said “my coffee?” And sometimes not, e.g. if I said “that?” In the former case it would often make sense for my interlocutor to either answer the question or say that they don’t know (“sure, that’s your coffee”/”I don’t know whether that’s your coffee”. In the latter they’re more likely to look puzzled and say “—- what?” (“that what?”).
Or suppose I utter the expression confidently. Sometimes I can be construed as having said something about the object I’m pointing to e.g. if I point to someone and say “the chair of the department”. And sometimes not e.g. if I point to someone and say “him”. In the former case it often makes sense for my interlocutor to agree, or disagree, or say “ok”. In the later, they’re more likely to look puzzled and say “what about it/him?”
Here are some examples and illustrations.
Suppose I point to a man drinking coffee and wearing dark glasses in the corner and I utter a name questioningly: “Hunter Thompson?” Then I can be easily understood as asking whether that man is Hunter Thompson.
This sort of example can be messed up if I point to the wrong kind of object for the kind of name. For example, if I point to the table we’re sitting at and say “Hunter Thompson?” my friend will probably decide that I’m not asking whether the table is Hunter Thompson on the grounds that he knows that I know that that isn’t Hunter Thompson. But in many cases context will settle that I am asking some question or other. For example if I arrived at the cafe after my friend and there are two coffee mugs on the table, incluing a half empty coffee mug at the place to his left, and I point to it and say “Katy?”, I can be construed as having asked whether that’s Katy’s mug.
But names also work with confident utterance to say something (rather than questioning utterance to ask something.) I could point to a picture of Hunter Thompson in a magazine and say “ooh, Hunter Thompson”, and be construed as claiming, for example, that the person the picture is a picture of is Hunter Thompson.
But I claim you can’t do this with many demonstratives. I can’t point to the man and say “him?”, or “that guy?” without my friend saying “what about him?” – that is, asking me what I’m asking. Similarly I can’t point to the coffee mug and say “that?” or even “that mug?” without prompting my friend to say “what about it?”
(Caveat: maybe you can do it with some very complex demonstratives. I could point to the guy in the dark glasses and whisper “that guy whose book you’re reading?”)
Unsurpisingly, it works with definite and indefinite descriptions. I can point to the guy and say “the author of the book you’re reading?” and be construed as asking whether the guy is the author of the book you are reading. And I can say insistently “the author of the book you’re reading” and be construed as asserting that the guy is the author of the book you’re reading.
Or I can point to the unfamiliar fruit in the still life my friend’s child is constructing on our table and say “a dragon fruit?” or “a vision of oddness!” and be construed as asking or asserting.
Indexicals seem to be rather an odd case. I can’t point to the man with the glasses and say “I?” or “me?” without my friend asking me to clarify what the hell I’m talking about. But maybe that’s like asking whether my mug is Hunter Thomson – it’s implausible that I could be asking or asserting whether that’s me. But I could point to the coffee cup and ask or assert “mine?”/”mine”. Or say “my coffee?”
One might think that this distinction tracks something related to the referential/attributive distinction. Perhaps it’s only expressions which have an attributive reading which can be uttered alone with a demonstration like this and only expressions which have no attributive reading which cannot be so used. (You’ll only think this is you think names can be used attributively, of course, but it seems to me that they could be.)
I think this distinction does track something like whether or not it’s possible to use an expression predicatively, by which I mean, to say something about an object (as opposed to to pick out an object in order to say something about it.)