It's Only A Theory

At the recent MS3 meeting, I gave a brief presentation on Pat Suppes contributions to thinking about models. One point is relevant to Contessa’s question about the original arguments in favor of the SVT over the statement view. At least two of the three founders of the SVT, Suppes and Beth (the third was Arthur Burks), were much concerned with the foundations of physics, Suppes with classical mechanics and Beth with quantum theory. They found attempting reconstructions in first (or even second) order logic to be impossibly cumbersome. The physics gets lost in the logic. To be convinced of this, one need only look at Richard Montague’s 1962 first order reconstruction of classical mechanics. [Deterministic Theories. In Formal Philosophy and Selected Papers of Richard Montague, ed. R. H. Thomason, 303-59. New Haven, Yale University Press, 1974.] As I remember, one can barely make out F= ma in something like Axiom 24. Set Theory and State Spaces are far more perspicuous than first order formulae. van Fraassen, who was inspired by Beth, had a similar motivation. The general idea of getting the philosophy of science closer to the science has been for me, and I think many others, a major attraction of the SVT, even though the primary interest has been understanding the actual practice of science rather than the foundations of theories.

I was thinking more about Gabriele's post on the semantic view of theories. Consider this quick argument in favour of a semantic view of theories:

1. Scientists believe (or at least accept) scientific theories;
2. Attitudes like belief and acceptance are held to propositions (certainly belief and acceptance ascriptions involve embedded 'that' clauses which seem to denote propositions);
3. So, scientific theories are propositions.

This is pretty clearly a semantic view of theories. But Gabriele, and I presume others, seem not to believe this is the semantic view of theories, as discussed in the literature. Could someone explain the difference, if there is one? For I do not at this stage see it, for reasons I'll now explain.

The conclusion of this argument is what I have always understood to be the semantic view of theories. If propositions are structured (i.e., not just sets of possible worlds), then the propositions which express scientific theories can easily be models in the model-theoretic sense; if theories have merely qualitative content, no one model will capture the proposition expressed (as qualitatively indistinguishable models will equally satisfy the theory), so the proposition expressed should be a set of models. (Things seem to be a little, but not much, trickier if propositions are unstructured.) In any case, there seems to be a clear correspondence between the propositions expressed by the sentences of some presentation of the theory and the models which satisfy those sentences, a close enough correspondence that reducing the one to the other doesn't seem unreasonable.

Bryan at Soul Physics has an interesting post about underdetermination here.

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?