The RDF specs should define a semantics so that an RDF statement on the web is interpreted as an assertion of that statement such that its author would be responsible in law as if it had been published in, say, a newspaper. There are gotchas in representing the current RDF model in a logical formalism. For example, a statement is defined as triple containing containing at least two, possibly three resources. Resources are not reasonable things to include in a triple. For example, what RDF'er's call a 'model' is called an 'abstract syntax' by logicians.
Logicians use the term model but for something quite different.
Appologies to Dan if I have misrepresented any of these.