These days most philosophers of science (PoSs) seem to subscribe to the semantic view of scientific theories, according to which scientific theories are collections of models (the question obviously become what kind of thing a scientific models is. For my take on this question see here). In the heydays of logical empiricism however, the prevailing view was the so-called syntactic view of theories, by which I mean here the view that scientific theories were collections of sentences. Logical empiricists, unfortunately, saddled this view with a host of other less plausible views about language and truth, which most philosophers today seem unwilling to accept. However arguments against such views are not arguments against what I call the syntactic view. So, was the rejection of the syntactic view a case of guilt by association or are there any serious arguments against the view itself (rather than the views that were usually held in conjunction with it)? If not, what are the arguments in favour of the semantic view (other than its supposedly being more empirically adequate)?
Thinking about it the only serious argument that I can think of that seems to target what I call the syntactic view (as I am intending it here) is the one according to which the same scientific theory can be formulated by using different sets of sentences (e.g. in English and French or in Lagrangian and Newtonian terms) and, therefore, the theory cannot be identified with any set of sentences. But what if we substitute sets of sentences with sets of propositions? (Would this work in the case of Newtonian and Lagrangean mechanics or would one have to say that the two are distinct theories?) The only obstacle I can see to this way of recasting the syntactic view this way was the logical empiricists' prejudice against propositions. But I don't see any reason to think of propositions as being more metaphysically mysterious than sentences (utterances are physical events but sentences like propositions seem to be abstract entities).
Am I missing something major?