Re: RT list: Non-sentential utterances, logical form, explicatures (e.g. in poetry)

I'm not sure I understand your argument/claim/petition.
I cannot point to what these phrase structure representations are on the physical level as I cannot point to what my representation of my mother, our representation of the Egyptian victory over Mubarak dictatorship, some people's idea about economics, our desire to be happy and hosts of other mental representations, are on the physical level --no less!
If you can, as I said before, I would be very interested in reading about it! If you can't, does that mean that you have no mental representations? [I humbly believe that you mix the cognitive frame of reference with the physical one, but I may be wrong, of course]

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I have pictures of my mother in my head, for example, and might visualize a time series (your economics example), and for most purposes what the physical explanation of these might be is not relevant.  But if "representation" is supposed to be a term of art in a  theory of linguistic competence, then I am not sure I am required to believe in them if they can't be cashed out in physical terms.  There are, incidentally, some writers that believe similarly; that the theoretical rubber has got to meet the physical road somewhere if semantic theory is to be taken seriously.  
 
Also, lets leave out the physical for a moment.  I am not sure there is even any mental (say, gathered from introspection) evidence that the kind of interpretation you are talking about happens. At least,  I don't work through the interpretive steps in assigning a meaning to a sentence in the same way as I work out a sum in my head, or work out the counter to a chess move, or even work out assigning meaning to a line the way Empson might have done for 7 types of Ambiguity.
 
M.J.Murphy